Innovating arch structures with fiber-reinforced polymer composites: A review

Abstract

Fiber-reinforced polymer (FRP) composites are a class of advanced non-metallic materials featuring advantages of high strength, light weight and excellent corrosion resistance. These advantages, in conjunction with the various methods available for making curved FRP members, create a wide range of possibilities for innovating arch structures with FRP composites. However, this subject has received inadequate research attention despite the exciting prospects demonstrated by pioneer studies. This paper provides a review on this subject with the aim to build a holistic picture and engage wider research participation. The paper begins with an overview of four feasible manufacturing/forming methods (vacuum infusion, filament winding, pultrusion and active bending), with an emphasis on their capability of creating curved FRP members and potential applications in arch structures. A review is next made on previous arch projects and relevant novel concepts, which are classified into two categories (all-FRP arches and FRP-incorporating hybrid arches) with distinct functionality and targeted areas of application. On the basis of this review, directions for future development of each of the two categories are highlighted, with a number of challenges and potential solutions discussed.

Keywords

Fiber-reinforced polymer arch structures manufacturing methods curved FRP members all-FRP arches FRP-incorporating hybrid arches

Introduction

Arches are curvilinear structures resting on supports at the two ends. An arch primarily bears axial compression due to the development of horizontal reaction forces at the supports, which effectively reduce the shearing force and bending moment at any section of the arch. This distinguishing feature enables arch structures to span a large distance.

Early examples of human-built arches, found in Mesopotamian brick architecture, date back to the second millennium BC (Rahman, 2015). This technique then spread to a number of civilizations in the ancient Near East in succession. However, the early applications were limited to underground structures, such as drains, in which case the horizontal reaction forces were resisted by the surrounding soil (Rasch, 1985). It was the Romans who first began systematic use of the arch structure in their engineering feats, which included applications in bridges, aqueducts and gates (Robertson, 1969). Withstanding the test of time, today, arches still remain a mainstream structural form. Due to their outstanding capabilities of spanning and load bearing, arches are favored by engineers in the design of long-span structures such as bridges and roofs, as well as heavy structures such as tunnel linings and dams. Arches have also found applications in smaller-scale structures, such as buildings and tents, thanks to their aesthetically pleasing appearance and ability to enclose space.

Development of building materials is the driving force behind the evolution of structures. Arches are no exception. Mainstream materials used for arches have shifted from masonry and timber in early times to concrete and steel nowadays. The use of modern building materials, in tandem with advances in construction technology, has substantially lifted the span limit and enriched the forms of arch structures. The world’s longest-span arch bridge, Pingnan Third Bridge (located in Pingnan, a county in China’s Guangxi Province), whose arch ribs are in the form of concrete-filled steel tubular truss, stands at a span of 575 m.

Along the development trajectory of building materials, fiber-reinforced polymer (FRP) composites have gained increasing popularity over the past few decades (Lu et al., 2022; Teng et al., 2002; Wang and Lau, 2021). FRP is a non-metallic, high-strength and lightweight composite material that has exceptional resistance to corrosion. When FRP composites first made their entrance to the field of civil engineering in the 1980s, they were mainly used in strengthening applications of reinforced concrete (RC) structures. The success in this area encouraged researchers to explore their potential for use in new construction. Their efforts have resulted in an expanding variety of FRP members, including reinforcing bars, profiles, confining tubes, cables and bridge decks, among others (Hollaway, 2010). To date, the applications of FRP in new construction have been mostly centered in the domain of linear members (i.e., beams and columns) and such-based structures (e.g., frames). By contrast, FRP’s potential for use in arch structures has received inadequate research attention due to the complexities arising from their curvilinear nature.

In fact, the unique properties of FRP composites, alongside the various methods available for making curved FRP members, offer diverse possibilities for the promotion of this new building material in arch structures. An obvious one that has paramount significance is to use FRP to address the issue of degradation caused by steel corrosion, which is a major challenge facing RC and steel structures (Cui et al., 2021; Koch et al., 2016; Roberge, 2019), including arch structures, especially those exposed to a corrosive environment (e.g., underground environments, marine and coastal areas, and cold regions where de-icing salts are frequently used) (Caratelli et al., 2016; Dagher et al., 2012; Jiang, 2020; Lee and Shin, 2010; Tang et al., 2020). Another possibility resides in lightweight all-FRP applications (Bell et al., 2020; Caron et al., 2009; Liu et al., 2021a; Potyrala, 2011; Pyrzowski and Miśkiewicz, 2017; Sobrino and Pulido, 2002). This scenario takes advantage of the lightweight feature of FRP, which allows all-FRP arches to be installed on site with a rapid speed, making them ideal for use in situations where construction speed is critical.

In view of the diverse and exciting opportunities for innovating arch structures with FRP, this subject deserves much wider research attention and participation. To this end, there exists a need to conduct a review of existing work scattered in the literature. Such a review is presented in this paper. The paper begins with an overview of four methods that are capable of making curved FRP members, followed by a review of previous arch projects and relevant novel concepts, which are classified into categories of all-FRP arches and FRP-incorporating hybrid arches. Based on this review, directions for future development of each of the two categories are highlighted, with a number of challenges and potential solutions discussed. The scope of this paper is limited to the use of FRP in arches for new construction; strengthening applications are not covered.

Manufacturing methods for curved FRP members

While a vast variety of manufacturing methods are available for composites production (GangaRao and Prachasaree, 2021; Zoghi, 2013), not all of them are suitable for infrastructure applications. The main limiting factors are the large size of structural members and the low profit margin of the construction industry. Therefore, any viable method must be able to make large-scale members at a low cost. The geometry of arches poses a third challenge, that is, the competence to create curved members. Based on these criteria, four different methods are selected and reviewed in this section, with an emphasis on their capability of creating curved FRP members and potential applications in arch structures. The first three are standard processes for composites production, while active bending is a technique used to form arches by bending ready-made and initially straight members (typically pultruded hollow-section profiles). The main features of the four methods reviewed in this section are summarized in Table 1.

Table 1.

Manufacturing/forming methods for curved FRP members.

Method	Automation level	Product form	Targeted application
Vacuum infusion	Relatively low	Complex-geometry objects	All-FRP arch bridge spans
Filament winding	High	Straight/curved tubes	Confining device for concrete arches
Pultrusion	High	Straight/curved profiles with a constant cross-sectional shape	FRP truss arches; arch bridge spans; reinforcement for concrete arches
Active bending	N/A*	Initially straight profiles (typically pultruded)	Rapidly assembled structures; arch ribs

Note: *Vacuum infusion, filament winding and pultrusion are standard manufacturing processes for composites production. In contrast, active bending is a technique used to form arches by bending ready-made and initially straight members (typically pultruded hollow-section profiles).

Vacuum infusion

Vacuum infusion, also known as vacuum-assisted resin transfer molding, is a process that uses vacuum pressure to drive a low-viscosity resin into a fiber bed (Hindersmann, 2019). Initially, the fiber bed is formed by laying out dry fiber materials on top of the surface of a custom mold which is sealed in a vacuum bag. The airtight mold is connected to an inlet valve at one end and a vacuum pump at the other (Figure 1). The pump extracts air from the space enclosed by the mold and the vacuum bag to create a vacuum that compacts the fiber bed. The resin is then infused from the inlet and is driven by the vacuum pressure (i.e., pressure difference between the resin supply and the vacuum) into the fiber bed. Finally, the formed part is de-molded after the resin cures.

Vacuum infusion provides a cost-effective solution to manufacturing large objects with complex geometries. It is traditionally used to make large objects, such as boat hulls and wind turbine blades (Beckwith and Hyland, 1999; Rajak et al., 2019). By adapting the mold into the target shape, vacuum infusion can be used to create arch bridge spans completely made of FRP using a single mold. The span size is generally limited by the transportation logistics, rather than by the vacuum infusion technology itself. Vacuum infusion is a relatively labor-intensive process and is difficult to be automated. Therefore, it is not suitable for high-volume production. Note that in the literature vacuum infusion is often used as a broad term that refers to a large class of variants (Hindersmann, 2019). The description of this process herein is brief and not intended to be exhaustive.

Filament winding

Filament winding is an automated process that involves winding resin-saturated, continuous strands of fiber over a rotating mandrel (Mantell and Springer, 1994). In this process, continuous strand rovings are fed through a resin bath and then delivered onto a rotating mandrel from a carriage that travels the length of the mandrel back and forth in a direction parallel with the mandrel axis (Figure 2(a)). The winding program stops once the target number of layers of fibers is applied. The laminate is then left on the mandrel for curing until the molded part is ready for removal from the mandrel.

Filament winding is a classical method used for manufacturing tubular parts of both open- and closed-end forms, such as tubes, pressure vessels and rocket motor cases (Azeem et al., 2022; Shen, 1995). The winding angle (i.e., the angle of fiber strand relative to mandrel axis) of the part can be tailored to satisfy specific mechanical needs. The tubular parts resulted from a filament winding process typically have a axisymmetric shape (Frketic et al., 2017; Rajak et al., 2021). Production of non-axisymmetric parts (Figure 2(b)), for example, those with a curved axis (e.g., pipe bends), is also possible, with the use of an advanced winder with multiple axes (Laval, 2006; Mantell and Springer, 1994).

In the field of structural engineering, filament-wound tubes have gained acceptance as a confining device (a confining tube has a winding angle close to the hoop direction, e.g., ± 80°) for concrete columns (Vincent and Ozbakkaloglu, 2013; Xie et al., 2020). This technique can be extended to small-scale arches without much difficulty by filling a curved FRP tube with a concrete core. It is also possible to further extend it to large-scale arches. In such an application, the arch may be built from short segments of concrete-filled FRP tube with some form of internal steel reinforcement that facilitates connection. The tube segment itself can be either linear or curvilinear, but the choice of the former is technically and economically more viable and should suffice in most situations.

Pultrusion

Pultrusion is also an automated process. It is used for the manufacture of profiles having a constant cross-sectional shape (e.g., channels, tubes and I-sections) and a length typically much larger than the dimensions of the cross section (Starr, 2000). Pultrusion is a portmanteau term created by a blend of “pull” and “extrusion” (Rajak et al., 2021). In this process, continuous fiber strands are guided through a resin bath for impregnation. The saturated fibers are then pulled through a metal die with a predefined shape. The die defines the cross-sectional shape of the profile and is heated for rapid curing of the resin. Finally, the molded profile exiting the die is conveyed to a platform, where it is cut into pre-programmed lengths by a cut-off saw (Figure 3(a)).

A conventional pultrusion process (known as linear pultrusion) is limited to fabricating straight profiles. This limitation has been removed in the latest development, termed curved pultrusion (or radius pultrusion) (Tonatto et al., 2020). In a curved pultrusion process, an additional processing step, incorporated between steps of molding and cutting, is employed to shape the partially cured profile to the desired curvature, by taking advantage of the high deformability of the resin matrix when it is not completely hardened (Figure 3(b)). Typically, only circular curvatures are permitted (Liu et al., 2021b).

Various possibilities exist for applications of pultruded products in arch structures. Straight profiles (e.g., channels, tubes and I-sections) are suitable for construction of FRP truss arches (Sobrino and Pulido, 2002). Large curved profiles can function as a standalone arch span (Liu et al., 2021a) while curved bars can serve as replacement for steel reinforcement in concrete arches (Caratelli et al., 2016; Tang et al., 2021). Of particular interest is the possibility to form arches by bending initially straight pultruded members, which is discussed in the subsequent sub-section.

Active bending

Unlike the three methods reviewed above, active bending is not a method for manufacturing FRP products from raw materials; rather, it is a technique for generating curved geometries from initially straight or flat members that are ready-made through active use of elastic bending (Douthe et al., 2010). Despite this difference, it is still included in this section as it is well suited to forming arches made of FRP, whose elastic strain limit, not paralleled by any other commonly used building material, is high enough to resist the large elastic deformation induced in the bending process.

Structures that derive their curved geometries through active bending are known as bending-active structures (Douthe et al., 2007; Lienhard et al., 2013). Bending-active arches are the simplest form of bending-active structures (Figure 4). More sophisticated forms include bending-active grid shells (Happold and Liddell, 1975; Nicholas et al., 2013; Pone et al., 2013) and bending-active continuous shells (Sonntag et al., 2017). Owing to the contradiction between the need for flexibility in the forming stage and the need for stiffness in the service stage, bending-active arches are usually limited to a small scale. In particular, the lightweight feature of FRP makes FRP bending-active arches suitable for use as rapidly assembled structures that are intended to provide temporary accommodation or usage (e.g., disaster-relief shelters and military crossing bridges). On the other hand, larger-scale FRP bending-active structures are also possible. In such a case, proper post-forming stiffening measures (e.g., adding stiffening cables) are needed for enhanced performance of the bending-active system in the service stage.

All-FRP arches

Pultruded arches

Pultruded FRP members have been used in bridge structures since early 1990s (Vedernikov et al., 2020). Among these applications, an early example concerning arch bridge is a footbridge completed in October 2001 in Lleida, Spain (Sobrino and Pulido, 2002). Having a span of 38 m, a rise of 6.2 m, and a deck width of 3 m, this footbridge was built to cross a roadway and a railway line between Madrid and Barcelona (Figure 5). The components of this double-tied arch bridge, including the two tied arch ribs, the truss connecting the two ribs, hangers and decks, were all made of glass FRP (GFRP) pultruded profiles. The overall curved shape of the arch ribs was achieved by assembling straight segments of GFRP profiles. All joints of the bridge were bolted using stainless steel brackets and bolts. The lightness (total weight of the footbridge was only approximately 19 t) derived from using GFRP allowed for rapid installation, which was completed by a crane within 3 hours (Pyrzowski and Miśkiewicz, 2017; Sobrino and Pulido, 2002), representing an important advantage as traffic interruptions can be minimized. Another important reason for choosing GFRP was that GFRP had no magnetic interaction with the electrified railway line.

A more recent example worth mentioning is a 20 m-span footbridge built in 2021 in Beijing, China (Liu et al., 2021a). The distinguishing feature of this bridge is that curved GFRP components manufactured by a curved-pultrusion process were directly used to form the arch span. Specifically, the proposed arch form is created by transverse mechanical connection of several identical paralleling glass GFRP I-sections that are curved-pultruded. This way, each pair of adjacent I-sections, with the edges of their flange plates further connected by adhesive bonding, forms a box section that has considerably enhanced torsional stiffness and resistance than the original I-sections. Besides, the webs are thickened to achieve a lower slenderness ratio and restrain the flange plates, thereby increasing the in-plane flexural stiffness and load-carrying capacity. Liu et al. (2021b) conducted destructive lab tests on full-scale arch spans and assessed their failure mode, load-carrying capacity and deflection responses. Subsequently, the footbridge was designed, assembled and tested under the serviceability limit state before it was installed on site by a crane (Figure 6). The test results showed satisfactory performance in strength, deflection and vibration properties, which demonstrate the significant prospect of the proposed form of curved-pultruded GFRP arch bridge.

Vacuum infusion-manufactured arches

Vacuum infusion offers a solution to manufacturing standalone arch spans using a single mold, where the need for connections between composite parts is eliminated. A frequently quoted example is the footbridge located in Moscow, Russia (Hollaway, 2013; Potyrala, 2011; Pyrzowski and Miśkiewicz, 2017). Completed in June 2008, it is the first composite bridge in Russia made by vacuum infusion. The footbridge consists of an arched central span and two side beams (Figure 7). The arch span is forked at the two ends, covering a distance of 22.6 m. The width of the footbridge is 2.8 m and the total weight is only approximately 5 t. Other documented examples include two FRP overpasses installed in the Netherlands as wildlife crossing passages. The two overpasses, both of which have a shallow arch shape, have a span of 24 m and 36 m, respectively (Bell et al., 2020).

The longest-span arch bridge manufactured by vacuum infusion is probably the Ooypoort GFRP footbridge in Demark, which officially opened in February 2014. This footbridge was built from three segments, which were joined together to span a distance of 56 m. All composite parts of the bridge were manufactured by vacuum infusion (Pyrzowski and Miśkiewicz, 2017). This bridge was designed to accommodate houseboats even in case of high water levels and withstand frequent flooding since it is located at the entrance of a nature reserve of a marshy area.

Bending-active arches

Although the history of bending-active arches can be traced to ancient times (Ashby and Cebon, 2005) when residents of Ma’dan (present-day southern Iraq) learned to use actively bent reed bundles to support their reed houses, the concept of FRP bending-active arch systems only emerged very recently. Caron et al. (2009) proposed the concept of FRP self-stressed bowstring footbridge. The proposed bowstring system consists of two bows (arch ribs) formed by elastic bending of pultruded straight GFRP pipes, which are stabilized by a carbon FRP (CFRP) string system composed of lower spanning cables and a web of secondary stays. The bridge decks are supported by crossbars fastened to the spanning cables (Figure 8). More recently, Bessini et al. (2019) proposed a similar concept of bending-active tied arch module. Each of the proposed modules is composed of a pultruded FRP rod bent into shape by a cable pulling at both ends of the rod. Secondary struts are placed at certain intervals along the rod to deviate the tensioning cable (Figure 9). They envisioned applications of such modules as construction units for lightweight footbridges and roofs, and built a 5 m-span prototype footbridge for demonstration. The prototype footbridge was an assembly of two of the proposed bending-active modules, which were connected by transverse links at both the rod and cable levels (Figure 9). In the authors’ view, the proposed modules may also find applications as rapidly assembled military crossing bridges.

FRP-incorporating hybrid arches

FRP bars-reinforced concrete Arch segments

FRP bars-reinforced concrete arch segments are mainly intended for underground tunnelling applications. Underground construction today has a life expectancy of over 100 years, with some projects reaching 200 years. Durability of tunnel linings, with particular reference to corrosion of steel reinforcement, is therefore critical. An attractive solution is to use pultruded curved GFRP bars as substitution for conventional steel reinforcement in concrete tunnel segments, especially for construction in a harsh environmental condition (e.g., sewer tunnels or aggressive soils). The use of GFRP bars brings an extra benefit related to the non-conductivity of GFRP. When tunnel rings assembled from GFRP bars-reinforced segments are installed at regular intervals of a conventional RC tunnel lining, they function as dielectric joints that interrupt the stray currents, thus providing a remedy to electro-corrosion of steel components. This method is particularly suitable for railway tunnels in urban areas where traditional electrical insulation measures are hard or costly to implement.

Due to the above advantages, GFRP bars-reinforced precast tunnel segments have received pioneer research efforts recently. Caratelli et al. (2016) and Tengilimoğlu (2019) conducted a series of full-scale tests on such segments (Figure 10) to evaluate their structural performance under flexure and a condition that simulated the thrust action of the tunnel boring machine. Caratelli et al. (2017) further compared three different GFRP reinforcement cage typologies (closed-ring, lattice, and wirenet) and concluded that the closed-ring typology appeared to be advantageous over the other two in terms of cost effectiveness and concrete crack control. Meda et al. (2018, 2019) and De Rivat et al. (2019) conducted similar tests on precast concrete tunnel segments reinforced with short steel fibers and GFRP bars and found that the presence of GFRP reinforcement enhanced the flexural strength and reduced the crack width of the precast segments. These efforts paved the way for practical applications. Recently, GFRP bars-reinforced precast tunnel segments were used in the construction of Milan Metro Line 4 in Italy (Manuele et al., 2020).

FRP reinforcement has also been envisaged for use in waterfront protective structures, where steel corrosion is of critical concern. In this respect, Tang et al. (2020) proposed the use of basalt FRP (BFRP) bars or hybrid steel-BFRP composite bars (SFCBs) to replace steel reinforcement in concrete arches/tunnels. The SFCB, initially proposed by Luo et al. (2009), takes the form of a steel bar with a BFRP coating, and is thus expected to provide ductility, in addition to corrosion resistance, to the protective structure that it reinforces. In protective engineering, ductility is also a favoured property needed to resist blast loads, such as an explosion. The proposed protective structures with BFRP or SFCB reinforcement are still in the development phase. A series of tests have been conducted on semi-circular arch specimens and such-based tunnels (Figure 11) to evaluate the static performance and blast resistance (Tang et al., 2020, 2021; Wu et al., 2022; Zhao et al., 2022).

FRP-concrete arch panels

The concept of FRP-concrete arch panels, proposed by Lee and Shin (2010; 2011), is similar to that of FRP bars-reinforced concrete arch segments. Both of them are intended for tunnelling applications. The main difference is that in an FRP-concrete arch panel, the FRP reinforcement is a pultruded curved profile rather than curved bars. In the studies of Lee and Shin (2010; 2011), the proposed arch panel is composed of a curved GFRP profile (in the form of I-sections with a shared bottom flange) and a concrete infill between and on top of the I-sections (Figure 12). The GFRP profile is manufactured by a curved-pultrusion process and sand-coated to enhance the bond behavior at the FRP-concrete interface. In addition to providing longitudinal reinforcement and shear resistance, the GFRP profile also serves as formwork for concrete casting. Jung et al. (2012) conducted flexure tests as well as numerical analysis on this form of arch panel. Both the experimental and theoretical results indicated a large shear movement at the FRP-concrete interface, especially at the tensile side due to bending-induced tensile stresses. Therefore, proper measures are needed to enhance the composite action between the two constituent materials. Connection between the arch panels, which is another essential practical issue, also needs to be addressed in future research.

Concrete-filled FRP tubular arches

A concrete-filled FRP tubular member (CFFTM) consists of an FRP tube filled with a plain or RC core. The FRP tube, typically filament-wound, not only provides confinement to the concrete core, but also serves as stay-in-place formwork which facilitates construction and protects the concrete core against environmental attacks. Due to the well-known fact that the compressive strength and ductility of concrete can be substantially enhanced through confinement, this technique is well suited to constructing CFFT columns (CFFTCs) and CFFT arches (CFFTAs), both of which primarily bear compression force.

While extensive research has been carried out on CFFTCs (e.g., Fam and Rizkalla, 2001a; Fam and Rizkalla, 2001b; Huang et al., 2021; Mirmiran and Shahawy, 1997; Pei et al., 2021; Xie et al., 2020; Xie et al., 2023; Yu and Teng, 2011; Zohrevand and Mirmiran, 2013), studies on CFFTAs have been mostly limited to a research group of University of Maine. It is worth noting that unlike most of the previous studies on CFFTMs, the FRP tubes used by this group were not filament-wound. Instead, they were manufactured using a vacuum infusion process (Dagher et al., 2012). The concept of CFFTA was initially proposed by this group in Tomblin (2006). Subsequently, a series of studies were conducted, including mechanical tests (Dagher et al., 2012; Goslin et al., 2011), fire tests (Goslin et al., 2014), sectional shape optimization (Goslin and Rofes, 2015), damage repair (Goslin and Arimond, 2015), soil-arch interaction (Walton et al., 2016a, 2016b), and health monitoring (Goslin and Tomlinson, 2016). Their efforts have led to the erection of more than 10 buried CFFTA bridges. One of them is shown in Figure 13. This bridge, located in Bradley, Maine, USA and completed in 2010, is supported by several parallel CFFTAs with a span of 8.5 m (Dagher et al., 2012). The CFFTAs were topped with an FRP decking that provided lateral support for concrete filling and created a surface for soil backfilling. Headwalls were installed at the outer CFFTAs to hold the soil backfill, with a pavement and guardrail that completed the bridge. Due to transportation limitations, all the built bridges of this form have been limited to a small span. Parry et al. (2014) proposed a segmental solution which requires connection of CFFTA segments to overcome the span limit. The proposed solution employs a combination of internal rebar reinforcing and an external FRP collar to connect adjacent CFFTA segments. However, to the best knowledge of the authors, this solution is still under development and has not been used in practical CFFTA bridge projects.

FRP-concrete-steel double-skin tubular arches

FRP-concrete-steel double-skin tubular members (DSTMs) are an enhanced variant of CFFTMs (e.g., Jiang, 2020; Jiang et al., 2023; Teng et al., 2007; Yao et al., 2015; Zhao et al., 2016). The difference between the two forms is that a DSTM has an inner steel tube in addition to the outer FRP tube (Figure 14). The space between the two tubes is filled with concrete while the steel tube typically remains hollow to reduce self-weight. The FRP tube insulates the steel tube as well as the concrete infill from the external environment; hence, steel corrosion is not a concern. The steel tube not only functions as longitudinal reinforcement, but most importantly, facilitates connection between DSTM segments. Such a segmental solution represents an important advantage as it removes the restriction on the scale of DSTM-based structures.

DSTMs were first developed at The Hong Kong Polytechnic University (Teng et al., 2004, 2007) as columns (DSTCs) and beams (DSTBs) (Xie, 2018; Yu et al., 2006; Zhao et al., 2016). After more than a decade of intensive research, their potential as arches (DSTAs) was recently explored. De Waal et al. (2018) proposed a novel arch bridge system completely consisting of DSTMs. Burnton et al. (2019) further built a full-scale prototype, in which DSTBs serving as bridge girders were upheld by DSTCs rising from the supporting DSTAs underneath (Figure 15). All segments, including those forming the DSTAs, had a linear shape to avoid the complexity involved in manufacturing curved tubes. Connection between the segments was achieved by welding of the steel tubes in combination with joining the FRP tubes using either the pre-preg or the wet lay-up technique. The FRP and steel tubes served as formwork for concrete casting. Shear studs were welded to the outer surface of the steel tube to enhance the composite action between the steel tube and the concrete infill. This hybrid bridge system represents an promising alternative to conventional arch bridge systems (Jiang, 2020), for its high load-bearing capacity, ductility and durability. It has potential to rival the spanning capacity of concrete-filled steel tubular arch bridges. Table 2 summarizes the key information of the arch projects and relevant concepts reviewed in the present and preceding sections.

Table 2.

Previous FRP-incorporating arch projects and relevant concepts.

Source	Category	Manufacturing/forming method	Form of FRP product	Year of completion	Location	Arch span	Form of application
Sobrino and Pulido (2002)	All-FRP	Pultrusion	Straight profile	2001	Spain	38 m	Footbridge
Liu et al. (2021b)	All-FRP	Pultrusion	Curved profile	2021	China	20 m	Footbridge
Hollaway (2013); Potyrala (2011); Pyrzowski and Miśkiewicz (2017)	All-FRP	Vacuum infusion	Bridge span	2008	Russia	22.6 m	Footbridge
Bell et al. (2020)	All-FRP	Vacuum infusion	Bridge span	2020	Netherlands	24/36 m	Wildlife crossing passage
Pyrzowski and Miśkiewicz (2017)	All-FRP	Vacuum infusion	Bridge span segment	2014	Demark	56 m	Footbridge
Caron et al. (2009)	All-FRP	Active bending	Straight profile	2009	France	4 m (1/10 scaled model)	Footbridge
Bessini et al. (2019)	All-FRP	Active bending	Straight profile	2019	Spain	5 m (scaled model)	Footbridge
Manuele et al. (2020)	Hybrid	Pultrusion	Curved bar	2014	Italy	About 3.5 m	Tunnel segment
Tang et al. (2020); Tang et al. (2021); Wu et al. (2022); Zhao et al. (2022)	Hybrid	Pultrusion	Curved bar	2020–2022	China	1.2 m (scaled model)	Waterfront protective structure
Lee and Shin (2010); Lee et al. (2011)	Hybrid	Pultrusion	Curved profile	2010	Korea	5.062 m	Tunnel segment
Dagher et al. (2012)	Hybrid	Vacuum infusion	Tube	2010	USA	8.5 m	Arch bridge
De Waal et al. (2018)	Hybrid	Filament winding	Tube	2014	Australia	12.5 m	Arch bridge

Summary and research needs

Brief summary

The review provided in the preceding two sections identifies two distinct paths toward applying FRP (with GFRP being the most commonly used due to its relatively low cost) in arch structures. One path is all-FRP arch structures and the other employs FRP in combination with concrete and in some cases steel to form hybrid arch structures. The first path leads to small- or medium-scale arches, which find their applications mostly as footbridges where the benefits of FRP materials are maximized and their weaknesses minimized. On the one hand, the lightweight feature of all-FRP footbridges allows for rapid installation by lifting the bridge into position as a whole using a crane. Typically, the installation process only takes a few hours to complete, which minimizes traffic interruptions. Other important benefits include minimal maintenance costs and zero magnetic interaction. The latter, which is an additional advantage of GFRP due to its non-conductivity, can be a decisive factor in situations where magnetic interaction is of concern (e.g., footbridges crossing electrified railway lines). On the other hand, a footbridge usually has a limited span and is not subjected to heavy loading. The problem of excessive deflection due to the relatively low modulus of elasticity of FRP is therefore not critical. Neither is the concern of fire safety as footbridges are usually located in an outdoor environment, where fires are less likely to occur and fire detection and evacuation are easier.

The second path, in contrast, chiefly leads to large-scale arch structures which are usually subjected to heavy loading. Targeted areas of application include tunnel linings and long-span arch bridges. In these structures, FRP alone is unable to deliver the strength and/or stiffness required, or is not cost-effective. Instead, it is used in combination with concrete with the primary aim to resolve the issue of steel corrosion, thereby saving maintenance costs and extending service life. Two possible approaches exist. The first is as substitution for steel reinforcement. The second is as external protective and confining tube for the concrete infill. In the latter approach, additional internal steel reinforcement (e.g., an inner steel tube) is preferred in order to provide flexural ductility and facilitate inter-segment connection, which is hard to accomplish with FRP alone owing to its relatively poor connectability. Obviously, due to the distinct objectives of these two paths, the associated research needs are different. The research needs specific to each of the two paths are addressed in the remainder of this section.

Research needs for All-FRP arches

Modular construction is deemed the way forward for future development of all-FRP arch footbridges. The pultrusion process is well suited to modular construction since it is a highly automated process efficient at manufacturing objects of identical shapes. For pultruded FRP members, the lamination structure may be optimized by adding multidirectional fiber fabrics in the pultrusion process (Madenci et al., 2020; Nunes et al., 2016) to avoid the undesired local failure modes caused by the lack of stiffness/strength in the transverse directions, as reported in previous studies (e.g., Hai et al., 2010; Nunes et al., 2016). While there is in principle no limit on the length of a pultruded profile, manufacture difficulty increases with the sectional size of the profile. The width of a typical footbridge generally prevents an all-in-one pultrusion solution, therefrom arises the need to pursue a modular solution that segments a footbridge into identical parallel spans (modules). The number of modular spans needed for assembly depends on the actual width of the footbridge with a consideration of a balance between manufacturing and assembling requirements. Modular construction is also possible with vacuum infusion, although the benefits of vacuum infusion are best exploited in creating standalone free-form arches with varying cross-sectional shapes using a single mold. When used for modular construction, vacuum infusion is less efficient than pultrusion owing to its lower level of automation. For a successful modular design, connection between the modular spans is critical. Metal (e.g., stainless steel) bolting is a potential solution. However, metal bolting disrupts fiber continuity and reduces assembling speed, although the FRP members may be locally strengthened during manufacturing or construction to achieve the desired strength, ductility and efficiency of bolting joints (Liu et al., 2020; Liu et al. 2021b). Furthermore, metal connection should be avoided in some special situations where requirements on corrosion and/or magnetic interference are demanding. In such cases, an all-FRP connection solution, including mechanical connections and adhesive bonding, is favored. Of particular interest is the development of mortise–tenon type joints, which can be realized with sectional shape designs of a convex side and a concave side, where the convex side fits with the concave side of the adjacent module to enable rapid assembly.

Bending-active arches are often used as supporting frames for temporary structures (e.g., tents and shelters). However, the possibility of using them as permanent structures remains inadequately explored. This possibility is discussed in a recent study (Habibi et al., 2022), which showed that as permanent structures, the span limit of FRP bending-active arches, without any post-forming stiffening measures, is between 10 to 30 m depending on the type of FRP used. The span limit may be further increased by adopting certain post-forming measures that enhance the stiffness of the arch. For example, the bending-active arch systems proposed by Caron et al. (2009) and Bessini et al. (2019) employ cables and struts to stiffen the bent arch rib. Future research should focus on the development of permanent bending-active arch structures. Potential application targets include footbridges and roofs. It is worth noting that the few pioneer studies on FRP bending-active arch systems (Bessini et al., 2019; Caron et al., 2009) have thus far been limited to scaled models, which differ from actual bending-active footbridges or roofs in terms of their scale and lifespan. A larger scale is associated with increased complexities in construction and a longer lifespan necessitates the need to consider time-dependent behavior. For scaled models or small-scale bending-active arches, it is practical to manually bend the beam into the arch shape. However, for larger-scale bending-active arches, the forming process requires additional equipment or measures, such as tensioning a cable pulling at both ends of the beam, or using a crane to hoist the beam with necessary mechanical bending at the beam ends. In addition, in the design of actual bending-active arches, the time-dependent behavior of creep and relaxation related to FRP materials is worth particular attention. FRP bending-active arches operate with significant bending prestresses induced in the forming process, making them more susceptible to the detrimental effects of creep and relaxation on time-dependent structural performance. Therefore, how the long-term behavior of FRP bending-active arches is influenced by the inherent forming-induced prestresses is an important issue to address. For design purposes, a proper limit on the level of prestressing needs to be proposed to restrict the detrimental effects of creep (Abdel-Magid et al., 2003; Douthe et al., 2010; Sá et al., 2011) and relaxation (Shi et al., 2017; Zhao et al., 2020; Zou, 2003).

Research needs for FRP-incorporating hybrid arches

Under this category, FRP bars-reinforced arch segments and DSTAs have shown promise for application in large-scale structures. The two hybrid forms are respectively intended for application as tunnel linings and long-span arch bridges, which represent the two most widely used classes of large-scale and heavily-loaded arch structures. However, a great deal of research is still needed on various aspects of the two types of hybrid arches, thus harnessing their full potential.

Despite the few pioneer applications of FRP bars-reinforced concrete segments in tunnel linings, a number of issues need to be addressed before their widespread application. First, proper testing methods need to be devised to characterize the basic mechanical properties of pultruded curved FRP bars. The strength and modulus of elasticity of such bars may be inferior compared to normal straight FRP bars due to the mechanical bending involved in the curved-pultrusion process. The bending effect may result in slacking and kinking of the fibers at or near the inner side of the bar, which tend to lower the strength and modulus of elasticity of the bar (Ahmed et al., 2010; Morphy, 1999). Existing standardized testing methods for straight FRP bars may not be directly applicable to curved FRP bars; adaption or innovation is needed. Second, the bond-slip behavior at a concrete-curved FRP bar interface needs investigation. The bonding along a concrete-FRP bar interface is generally weaker than that along a concrete-steel bar interface (Wei et al., 2019; Xiong et al., 2022). This weakness may be exacerbated when curved FRP bars are used. The reason is that the opening of concrete cracks tends to cause a local straightening effect to the curved tensile reinforcing bar (i.e., the curved bar undergoes a local reduction in curvature). If the bar is made of FRP, the level of reduction in curvature would become more significant due to the low modulus of elasticity of FPP compared to steel, thus causing a more significant interfacial slip. Therefore, there exists a need to conduct bond-slip tests as a basis to develop reliable bond-slip models specific to concrete-curved FRP bar interfaces. Third, more tests are needed, especially full-scale tests on assembled tunnel rings. Existing tests have been limited to the segment level. Even at this level, available test data is limited. Full-scale assembly-level tests should be conducted under more realistic conditions (e.g., circumferential multi-point loading using separately controlled actuators), after a solid understanding of segment-level behavior is first established.

DSTA bridges represent a potent competitor to concrete-filled steel tubular arch bridges, particularly in the context of a corrosive environment (e.g., a marine or coastal environment). Note that the advantage of being corrosion-resistant, brought by the provision of an outer FRP tube that conceals the corrosion-prone steel tube, is realized at a cost of ease in connection. Therefore, innovation in connection techniques lies at the core of future research. The most challenging part resides in realizing the joints where different types of members converge (e.g., DSTA-DSTC joints). A potential solution is to separate such joints from the members that they connect so that they can be prefabricated. Furthermore, the steel tube of the joint as well as that of the member can be flanged to enable member-joint and member-member connection so that welding work at the construction site is minimized. With this joint solution, the members can either be prefabricated or cast on site. The former option is particularly attractive as it minimizes wet work at the construction site, shortens construction time and reduces construction costs.

For DSTA bridges, the bond between the steel tube and the concrete is of great importance to ensure the composite action between the two. The steel tube-to-concrete bond may be improved by shear connectors which can also serve as the stiffeners to the steel tube to enhance its buckling capacity (Huang et al., 2020; Peng et al., 2018). The connectors may also enhance the confinement to the concrete and play a role in the connections between different components/members if designed properly. The selection of form and configuration of shear connectors therefore offers opportunities for structural optimization. Furthermore, the present lack of design standards and/or research for the FRP-incorporating hybrid arches under various loading scenarios also impedes their wide application. There is, for example, a scarcity of research on the torsional behavior of the hybrid arches, which may be critical in some scenarios. Practical applications should begin with small-scale DSTA bridges and follow an incremental route that gradually leads to safe and confident construction of long-span DSTA bridges.

Concluding remarks

In the past few decades, the use of FRP composites has inspired numerous structural innovations taking advantage of their unique properties. The vast majority of these innovations have been centered in the domain of linear members (i.e., beams and columns) and such-based structural forms (e.g., frames). In contrast, despite also being a mainstream structural form, arches have received inadequate research attention due to the complexities arising from their curvilinear nature. In fact, a variety of methods are available for making curved FRP members, whose diverse forms offer a wide range of possibilities for innovating arch structures with FRP composites. The lack of a review of the scattered literature published in this area motivated the writing of this paper, in an attempt to build a holistic picture and engage wider research participation.

Vacuum infusion, filament winding, pultrusion, and active bending are the four methods reviewed in the paper deemed suitable for making curved FRP members. The first three are standard manufacturing processes that are capable of producing large-scale members at a low cost. Active bending, by contrast, is an efficient yet inexpensive technique capable of forming FRP arches by elastic bending of initially straight members (typically pultruded hollow-section profiles). Each of the four methods has its own merits and intended areas of application with respect to arch structures. Subsequently, a review is made on previous arch projects and relevant novel concepts divided into two distinct categories, namely, all-FRP arches and FRP-incorporating hybrid arches. The former category is intended for small- or medium-scale arch structures. In this category, the lightweight feature of FRP is exploited to enable rapid construction, making them ideal for use in situations where construction speed is critical. Targeted applications include lightweight footbridges and temporary structures (e.g., disaster-relief shelters and military crossing bridges). The latter category is chiefly intended for large-scale arch structures. In this category, the corrosion resistance of FRP is exploited to offer a solution to the steel corrosion issue encountered in conventional arch structures. Targeted applications include tunnel linings and long-span arch bridges. On this basis, directions for future development of each of the two categories are pointed out, with a number of specific research needs discussed.

In sum, the distinctive properties of FRP materials and the diverse forms of FRP members provide a wide range of opportunities, which cover the full spectrum of span size, for contributing to the advancement of the classical arch structure. Admittedly, promoting FRP for use in arch structures also faces challenges, such as the increased difficulty in connection. Potential solutions to such challenges have been discussed in this paper, paving the way for future innovation toward the long-term goal of realizing lighter, stronger and more durable arch structures with a faster construction speed and a lower life-cycle cost.

Footnotes

Acknowledgements

The authors acknowledge the opportunity provided by the PolyU-ZJU Joint PhD Program for the first author to undertake a joint PhD program under the supervision of the two corresponding authors.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors are grateful for the financial support received from the National Natural Science Foundation of China (Project No.: 51778569) and the Hong Kong Research Grants Council (Project No.: T22-502/18-R).

ORCID iD

T Jiang

References

Abdel-Magid

Lopez-Anido

Smith

, et al. (2003) Flexure creep properties of E-glass reinforced polymers. Composite Structures 62: 247–253.

Ahmed

El-Sayed

El-Salakawy

, et al. (2010) Bend strength of FRP stirrups: comparison and evaluation of testing methods. Journal of Composites for Construction 14: 3–10.

Ashby

Cebon

(2005) Materials selection in mechanical design. MRS Bulletin 30: 995.

Azeem

Kumar

, et al. (2022) Application of filament winding technology in composite pressure vessels and challenges: a review. Journal of Energy Storage 49: 103468.

Beckwith

Hyland

(1999) Resin Transfer Molding: A Decade of Technology Advances. Resin Transfer Molding. SAMPE Monograph, pp. 1–14.

Bell

Fick

Ament

, et al. (2020) The use of fiber-reinforced polymers in wildlife crossing infrastructure. Sustainability 12: 1557.

Bessini

Lazaro

Casanova

, et al. (2019) Efficiency-based design of bending-active tied arches. Engineering Structures 200: 109681.

Burnton

McDonnell

Fernando

(2019) Design and Construction of a Hybrid Double–Skin Tubular Arch Bridge. In: 9th Australian Small Bridges Conference, Queensland, Australia, 2019, pp. 45–50.

Caratelli

Meda

Rinaldi

, et al. (2016) Precast tunnel segments with GFRP reinforcement. Tunnelling and Underground Space Technology 60: 10–20.

10.

Caratelli

Meda

Rinaldi

, et al. (2017) Optimization of GFRP reinforcement in precast segments for metro tunnel lining. Composite Structures 181: 336–346.

11.

Caron

Julich

Baverel

(2009) Selfstressed bowstring footbridge in FRP. Composite Structures 89: 489–496.

12.

Cui

Dong

, et al. (2021) Improved time-dependent seismic fragility estimates for deteriorating RC bridge substructures exposed to chloride attack. Advances in Structural Engineering 24: 437–452.

13.

Dagher

Bannon

Davids

, et al. (2012) Bending behavior of concrete-filled tubular FRP arches for bridge structures. Construction and Building Materials 37: 432–439.

14.

De Rivat

Giamundo

Meda

, et al. (2019) Hybrid solution with fiber reinforced concrete and glass fiber reinforced polymer rebars for precast tunnel segments. In: Tunnels and Underground Cities: Engineering and Innovation Meet Archaeology, Architecture and Art. CRC Press, pp. 2018–2025.

15.

De Waal

Jiang

Torres

, et al. (2018) Design and construction of a hybrid double-skin tubular arch bridge. In: 9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering, CICE 2018, Paris, France, 2018: International Institute for FRP in Construction (IIFC), pp. 878–887.

16.

Douthe

Baverel

Caron

(2007) Gridshell in composite materials: towards wide span shelters. Journal of the International Association for Shell and Spatial structures 48: 175–180.

17.

Douthe

Caron

Baverel

(2010) Gridshell structures in glass fibre reinforced polymers. Construction and Building Materials 24: 1580–1589.

18.

Fam

Rizkalla

(2001a) Behavior of axially loaded concrete-filled circular fiber-reinforced polymer tubes. Structural Journal 98: 280–289.

19.

Fam

Rizkalla

(2001b) Confinement model for axially loaded concrete confined by circular fiber-reinforced polymer tubes. Structural Journal 98: 451–461.

20.

Frketic

Dickens

Ramakrishnan

(2017) Automated manufacturing and processing of fiber-reinforced polymer (FRP) composites: an additive review of contemporary and modern techniques for advanced materials manufacturing. Additive Manufacturing 14: 69–86.

21.

GangaRao

Prachasaree

(2021) FRP Composite Structures: Theory, Fundamentals, and Design. Boca Raton: CRC.

22.

Goslin

Arimond

(2015) Bridge-in-a-Backpack (TM). Task 7: Investigation of Damage and Repairs for Concrete Filled FRP Tubular Arches. Maine: Dept of Transportation.

23.

Goslin

Rofes

(2015) Bridge-in-a-Backpack (TM). Task 2.1 and 2.2: Investigate Alternative Shapes with Varying Radii. Maine: Dept of Transportation.

24.

Goslin

Tomlinson

(2016) Bridge-in-a-Backpack (TM). Task 6: Guidelines for Long Term Inspection and Maintenance. Maine: Dept of Transportation.

25.

Goslin

Walton

Davids

, et al. (2011) Bridge-in-a-Backpack (TM). Task 1: Investigation of Span Lengths up to 70 Feet. Maine: Dept of Transportation.

26.

Goslin

Pomeroy

Dagher

, et al. (2014) Bridge-in-a-Backpack (TM). Task 8: Investigation of Bridge Performance Under Extreme Temperatures. Maine: Dept of Transportation.

27.

Habibi

Rhode Barbarigos

Keller

(2022) Fiber-polymer composites for permanent large-scale bending-active elastica beams. Composite Structures 294: 115809.

28.

Hai

Mutsuyoshi

Asamoto

, et al. (2010) Structural behavior of hybrid FRP composite I-beam. Construction and Building Materials 24: 956–969.

29.

Happold

Liddell

(1975) Timber lattice roof for the mannheim bundesgartenschau. Structural Engineering 53: 99–135.

30.

Hindersmann

(2019) Confusion about infusion: an overview of infusion processes. Composites Part A: Applied Science Manufacturing 126: 105583.

31.

Hollaway

(2010) A review of the present and future utilisation of FRP composites in the civil infrastructure with reference to their important in-service properties. Construction and Building Materials 24: 2419–2445.

32.

Hollaway

(2013) Applications of Advanced Fibre-Reinforced Polymer (FRP) Composites in Bridge Engineering: Rehabilitation of Metallic Bridge Structures, All-FRP Composite Bridges, and Bridges Built with Hybrid Systems. Guildford, UK: Elsevier.

33.

Huang

Zhang

, et al. (2020) Circular hybrid double-skin tubular columns with a stiffener-reinforced steel inner tube and a large-rupture-strain FRP outer tube: compressive behavior. Thin-Walled Structures 155: 106946.

34.

Huang

Xiao

Qin

, et al. (2021) Mechanical behaviors of GFRP tube confined recycled aggregate concrete with sea sand. Advances in Structural Engineering 24: 1196–1207.

35.

Jiang

(2020) Hybrid FRP-Concrete-Steel Double-Skin Tubular Truss Bridge: Design, Construction and Testing. The School of Civil Engineering. Queensland, Australia: The University of Queensland.

36.

Jiang

Lin

Xie

(2023) Behavior of large-scale hybrid FRP-concrete-steel double-skin tubular columns subjected to eccentric compression. Engineering Structures 275: 115258.

37.

Jung

Park

Kim

(2012) A study on the behavior characteristics of curved FRP-concrete composite panel. Advanced Materials Research 557–559: 375–380.

38.

Koch

Varney

Thompson

, et al. (2016) International measures of prevention, application, and economics of corrosion technologies study. NACE international 216: 2–3.

39.

Laval

(2006) CADWIND 2006–20 years of filament winding experience. Reinforced Plastics 50: 34–37.

40.

Lee

Shin

(2010) A numerical study on feasibility of the circled fiber reinforced polymer (FRP) panel for a tunnel lining structure. Journal of Korean Tunnelling and Underground Space Association 12: 451–461. (in Korean).

41.

Lee

Shin

Kim

(2011) Study on mechanical behavioral characteristics of the curved FRP-concrete composite member for utilization as a tunnel lining structure. Journal of Korean Tunnelling and Underground Space Association 13: 149–158. (in Korean).

42.

Lienhard

Alpermann

Gengnagel

, et al. (2013) Active bending, a review on structures where bending is used as a self-formation process. International Journal of Space Structures 28: 187–196.

43.

Liu

Wang

, et al. (2020) Optimization of multi-directional fiber architecture for resistance and ductility of bolted FRP profile joints. Composite Structures 248: 112535.

44.

Liu

Wang

, et al. (2021a) Resistance and ductility of FRP composite hybrid joints. Composite Structures 255: 113001.

45.

Liu

Feng

, et al. (2021b) Developing an innovative curved-pultruded large-scale GFRP arch beam. Composite Structures 256: 113111.

46.

Yang

Ruan

, et al. (2022) A comparative study of the flexural performance of hybrid-reinforced (glass fiber reinforced polymer and steel bars) concrete beams before and after exposure to chloride environment. Advances in Structural Engineering 25: 1295–1309.

47.

Luo

, et al. (2009) Study on fabrication technique of steel fiber composite Bar (SFCB). Earthquake Resist Engineering Retrofit 31: 28–34. (in Chinese).

48.

Madenci

Özkılıç

Gemi

(2020) Buckling and free vibration analyses of pultruded GFRP laminated composites: experimental, numerical and analytical investigations. Composite Structures 254: 112806.

49.

Mantell

Springer

(1994) Filament winding process models. Composite Structures 27: 141–147.

50.

Manuele

Bringiotti

Lagana

, et al. (2020) Fiber glass and “green” special composite materials as structural reinforcement and systems; use and applications from Milan Metro, Brenner Tunnel up to high speed train Milan–Genoa. In: Tunnels and Underground Cities: Engineering and Innovation Meet Archaeology, Architecture and Art. CRC Press, pp. 2625–2634.

51.

Meda

Rinaldi

Spagnuolo

, et al. (2018) Experimental behaviour of precast tunnel segments in steel fiber reinforcement with GFRP rebars. Fibre Reinforced Concrete: From Design to Structural Applications. Desenzano, Italy: Joint ACI-fib-RILEM International Workshop.

52.

Meda

Rinaldi

Spagnuolo

, et al. (2019) Hybrid precast tunnel segments in fiber reinforced concrete with glass fiber reinforced bars. Tunnelling and Underground Space Technology 86: 100–112.

53.

Mirmiran

Shahawy

(1997) Behavior of concrete columns confined by fiber composites. Journal of structural engineering 123: 583–590.

54.

Morphy

(1999) Behaviour of Fibre-Reinforced Polymer (FRP) Stirrups as Shear Reinforcement for Concrete Structures. Winnipeg, Canada: University of Manitoba.

55.

Nicholas

Hernández

Gengnagel

(2013) The Faraday Pavilion: activating bending in the design and analysis of an elastic gridshell. In: Proceedings of the Symposium on Simulation for Architecture & Urban Design, San Diego, America, 2013, pp. 1–8.

56.

Nunes

Correia

Silvestre

(2016) Structural behavior of hybrid FRP pultruded beams: experimental, numerical and analytical studies. Thin-Walled Structures 106: 201–217.

57.

Parry

Rofes

Lopez Anido

(2014) Splicing and Local Reinforcement of Concrete Filled FRP Tubes. Maine: Dept of Transportation.

58.

Pei

Wang

, et al. (2021) Axial monotonic and cyclic compressive behavior of square GFRP tube-confined steel-reinforced concrete composite columns. Advances in Structural Engineering 24: 25–41.

59.

Peng

Hadi

, et al. (2018) Compressive behavior of hybrid double-skin tubular columns with a rib-stiffened steel inner tube. Composite Structures 204: 634–644.

60.

Pone

Colabella

Parenti

, et al. (2013) Construction and form-finding of a post-formed timber grid-shell. In: 2nd International Conference on Structures and Architecture, Guimaraes, Portugal, 2013: Crc Press-Taylor & Francis Group, pp. 245–252.

61.

Potyrala

(2011) Use of Fibre Reinforced Polymeromposites in Bridge Construction. State of the Art in Hybrid and All-Composite Structures. Catalonia, Spain: Polytechnic University of Catalonia.

62.

Pyrzowski

Miśkiewicz

(2017) Modern GFRP composite footbridges. In: Environmental Engineering” 10th International Conference, Ottawa, Canada, 2017. Environmental Engineering, pp. 1–8.

63.

Rahman

(2015) Islamic architecture and arch. International Journal of Built Environment and Sustainability 2: 8–16.

64.

Rajak

Pagar

Menezes

, et al. (2019) Fiber-reinforced polymer composites: manufacturing, properties, and applications. Polymers 11: 1667.

65.

Rajak

Wagh

Linul

(2021) Manufacturing technologies of carbon/glass fiber-reinforced polymer composites and their properties: a review. Polymers 13: 3721.

66.

Rasch

(1985) Die Kuppel in der römischen Architektur: Entwicklung, Formgebung, Konstruktion: Dt. Kunstverl.

67.

Roberge

(2019) Handbook of Corrosion Engineering. New York, USA: McGraw-Hill Education.

68.

Robertson

(1969) Greek and Roman Architecture. Cambridge, UK: Cambridge University.

69.

Sá

Gomes

Correia

, et al. (2011) Creep behavior of pultruded GFRP elements–Part 1: literature review and experimental study. Composite Structures 93: 2450–2459.

70.

Shen

(1995) A filament-wound structure technology overview. Materials Chemistry and Physics 42: 96–100.

71.

Shi

Wang

Huang

, et al. (2017) Relaxation behavior of prestressing basalt fiber-reinforced polymer tendons considering anchorage slippage. Journal of Composite Materials 51: 1275–1284.

72.

Sobrino

Pulido

MDG

(2002) Towards advanced composite material footbridges. Structural engineering international 12: 84–86.

73.

Sonntag

Bechert

Knippers

(2017) Biomimetic timber shells made of bending-active segments. International Journal of Space Structures 32: 149–159.

74.

Starr

(2000) Pultrusion for Engineers. America: CRC.

75.

Tang

Zhou

Feng

, et al. (2020) Blast responses and damage evaluation of concrete protective arches reinforced with BFRP bars. Composite Structures 254: 112864.

76.

Tang

Zhou

Feng

, et al. (2021) Concrete protective arches reinforced with BFRP bars: construction and quasi-static structural performances. Tunnelling and Underground Space Technology 108: 103731.

77.

Teng

Chen

Smith

, et al. (2002) FRP-Strengthened RC Structures. West Sussex, England: John Wilkey & Sons, Ltd.

78.

Teng

Wong

(2004) Hybrid FRP-concrete-steel double-skin tubular columns: stub column tests. In: International Conference on Steel and Composite Structures [ICSCS], Seoul, Korea, 2004.

79.

Teng

Wong

, et al. (2007) Hybrid FRP–concrete–steel tubular columns: concept and behavior. Construction and Building Materials 21: 846–854.

80.

Tengilimoğlu

(2019) An Experimental Study to Investigate the Possibility of Using Macro-Synthetic Fibers in Precast Tunnel Segments. Civil Engieering. Ankara, Turkey: Middle East Technical University.

81.

Tomblin

(2006) Buried FRP-Concrete Arches. Civil Engineering. Marine, America: The University of Maine.

82.

Tonatto

MLP

Tita

Amico

(2020) Composite spirals and rings under flexural loading: experimental and numerical analysis. Journal of Composite Materials 54: 2697–2705.

83.

Vedernikov

Safonov

Tucci

, et al. (2020) Pultruded materials and structures: a review. Journal of Composite Materials 54: 4081–4117.

84.

Vincent

Ozbakkaloglu

(2013) Influence of fiber orientation and specimen end condition on axial compressive behavior of FRP-confined concrete. Construction and Building Materials 47: 814–826.

85.

Walton

Davids

Landon

, et al. (2016a) Simulation of buried arch bridge response to backfilling and live loading. Journal of Bridge Engineering 21: 04016052.

86.

Walton

Davids

Landon

, et al. (2016b) Experimental evaluation of buried arch bridge response to backfilling and live loading. Journal of Bridge Engineering 21: 04016053.

87.

Wang

Lau

(2021) Atomistic investigation of GFRP composites under chloride environment. Advances in Structural Engineering 24: 1138–1149.

88.

Wei

Liu

Xiong

, et al. (2019) Bond performance between fibre-reinforced polymer bars and concrete under pull-out tests. Construction and Building Materials 227: 116803.

89.

Zhou

, et al. (2022) Dynamic responses of blast-loaded shallow buried concrete arches strengthened with BFRP bars. Materials 15: 535.

90.

Xie

(2018) Behavior of Large-Scale Hybrid FRP-Concrete-Steel Double-Skin Tubular Columns Subjected to Concentric and Eccentric Compression. Hong Kong, China: The Hong Kong Polytechnic University.

91.

Xie

Lin

Teng

, et al. (2020) Modelling of concrete-filled filament-wound FRP confining tubes considering nonlinear biaxial tube behavior. Engineering Structures 218: 110762.

92.

Xie

Lam

Jiang

(2023) Compressive behavior of GFRP tubes filled with self-compacting concrete. Journal of Composites for Construction 27: 04022103.

93.

Xiong

Zhou

, et al. (2022) Bond behavior of basalt fiber reinforced polymer bars in seawater sea-sand concrete exposed to daily temperature variations. Advances in Structural Engineering 25: 2021–2039.

94.

Yao

Jiang

, et al. (2015) Experimental investigation on large-scale slender FRP-concrete-steel double-skin tubular columns subjected to eccentric compression. Advances in Structural Engineering 18: 1737–1746.

95.

Teng

(2011) Design of concrete-filled FRP tubular columns: provisions in the Chinese technical code for infrastructure application of FRP composites. Journal of Composites for Construction 15: 451–461.

96.

Wong

Teng

, et al. (2006) Flexural behavior of hybrid FRP-concrete-steel double-skin tubular members. Journal of Composites for Construction 10: 443–452.

97.

Zhao

Teng

, et al. (2016) Behavior of large-scale hybrid FRP-concrete-steel double-skin tubular beams with shear connectors. Journal of Composites for Construction 20(5): 0401601510401601511.

98.

Zhao

Mei

(2020) Long-term mechanical properties of FRP tendon–anchor systems—a review. Construction and Building Materials 230: 117017.

99.

Zhao

Tang

Wang

, et al. (2022) Blast responses of shallow-buried prefabricated modular concrete tunnels reinforced by BFRP-steel bars. Underground Space 7: 184–198.

100.

Zoghi

(2013) The International Handbook of FRP Composites in Civil Engineering. Florida, USA: CRC.

101.

Zohrevand

Mirmiran

(2013) Seismic response of ultra-high performance concrete-filled FRP tube columns. Journal of Earthquake Engineering 17: 155–170.

102.

Zou

PXW

(2003) Long-term properties and transfer length of fiber-reinforced polymers. Journal of Composites for Construction 7: 10–19.