**1. Introduction**

The feasibility of designing a super-long-span bridge with new materials in 2050 is studied. Longer bridge spans have the benefits of increased horizontal navigation clearances and reduced risk of ship collisions with piers [1]. The length of very long span suspension and cable-stayed bridges are often limited by the weight of the cables. As spans increase, the cables experience high stresses due to their own self-weight, and the overall structure becomes less

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

stiff as the stiffening contribution of the deck becomes negligible [1]. Therefore, strong but light-weight materials must be used in the design of super-long-span bridges.

(1067 m span), Golden Gate Bridge (1280 m span) and Wickwire Run bridge from USA, Forth Road Bridge (1005 m span) from Scotland, and Tagus Bridge (1013 m span) from Portugal, and so on. These ACS components are cheaper with durability, light weight, low cost, speed of construction, ease of transportation, and they show superior mechanical properties (e.g., tensile, compression, shear strength) than iron, steel and stone. Therefore, such advanced carbon fibre-reinforced polymer (CFRP) composite materials are promising candidates in the future for the construction of ultra-super-long bridges. It is feasible to develop over 10,000 span stable super-long bridges using new concepts. A new concept of engineering that is used

The Feasibility of Constructing Super-Long-Span Bridges with New Materials in 2050

http://dx.doi.org/10.5772/intechopen.75298

7

for nanoscale modelling of super-long bridges can be described in following sections.

strength of 1600 MPa of M55\*\*UD carbon fibre.

**2. Structural system**

**2.1. Structural members**

Finite element models were created in Strand7 [3], and the results show that a maximum deflection of 8.3 m occurs under the combination of dead and wind (G+W) load, which slightly exceeds the AS5100 [11] limit of 6.3 m. Furthermore, a 32.4 m transverse deflection is found under the dynamic wind analysis. Maximum tensile stresses of 1154 and 1152 MPa are observed in the catenary cables and stayed cables, respectively, which are below the tensile

The design of this long-span bridge is based on the Golden Gate Bridge, therefore structural member types are essentially similar to the Golden Gate Bridge, which consists of a bridge deck with a supporting trusses and beams system, two pylons, catenary cables, vertical hangers and stayed cables and eight lanes of vehicle traffic. The design of the central span between the two pylons is based on a typical suspension bridge, while the two edge spans are similar to a cablestayed bridge. The superstructure spanning between the two pylons is hung by vertical suspenders at 15-m intervals, which is the same as a typical suspension bridge. These vertical hangers carrying the loads on the deck are supported by the catenary cables suspended between the two pylons. Additionally, the stay cables at the two edge spans connecting the top of the pylons and the ends of the bridge are anchored by the abutment anchors at each end of the bridge. The cables directly running from the tower to the deck form a fan-like pattern on a series of parallel lines. Due to the different stress modes on the structural members, different materials are selected for each member based on their properties such as ultimate tensile and compressive strength, density and Young's modulus. The properties of the materials used in the bridge model are listed in

**Table 1** [7–9]. The material selection is further discussed for each structural member.

The superstructure of the bridge consists of four major components: the bridge deck, permanent formwork, the cross girder and the deck truss system. The 0.5-m-thick bridge deck is made up of reinforced concrete while the material applied to the rest of the components of the superstructure is standard carbon fibre to reduce the self-weight of the superstructure. **Figure 1** shows the details of the arrangement of the structural members in the superstructure (without the bridge deck). As shown in **Figure 1**, the truss system resisting tensile or compressive force is attached to the cross girders running across the driving direction of the bridge.

There are many new high-strength materials with low density like carbon fibre with epoxy, graphene oxide and alumina-polymer composites. Some materials have much better mechanical performances than steel or concrete but are only used in some high-tech industries such as aerospace, wind energy and automotive industries due to their high price. By 2050, the new materials are likely to be used extensively in construction due to the reduced cost in the development process of new materials [2]. This paper presents and analyses a super-long-span bridge design which has a total span of 4440 m with 40 m width deck and two 702-m-high pylons. The bridge design is based on the Golden Gate Bridge and a finite element model is created in Strand7 [3] which is a modification to the Golden Gate Bridge model developed by [4]. The central span of the bridge is 3780 m, which is three times the span of the Golden Gate Bridge of 1260 m, while the length of the two end spans is the same at 330 m. Previous studies have been conducted on super-long cable-stayed bridges using carbon fibre reinforced polymer [5] and on long-span suspension bridges using fibre-reinforced polymer [6]. Special techniques are adopted in this design where the bridge combines the advantages of a suspension bridge and a cable-stayed bridge to minimise the deflection of the superstructure and the pylons. The material of the catenary cables and stay cables are changed to a lightweight fibre carbon composite [7] with high stiffness and high strength, and standard carbon fibre is used in the superstructure and the vertical hangers. Finally, the stayed-cables of the bridge are pre-strained in this design.

Carbon nanofibres have cylindrical shapes with graphene layers constructed in the morphology of cones or plates or sheets, with an average diameter of 50–100 nm and an average length of 50–200 um, exceptional thermal and mechanical properties (as high as elastic modulus of 600 GPa, tensile strength of 8.7 GPa, surface area 40 m2 /g), which offer a wide range of applications in the civil engineering discipline (e.g. bridges, roads, railways, tunnels, airports, ports and harbours), and other areas such as aerospace, automotive, sports goods material, and so on. Reinforcement of such new nanocarbons with polymeric materials further boosts their mechanical properties through different fabrication technologies such as wet/hand lay-up/ spray lay-up, autoclave curing, filament winding, pultrusion, wet/hand lay-up, and so on. These extraordinary properties of advanced hybrid composites have enabled the design engineers to use them in the renewal of civil infrastructure ranging from the strengthening of reinforced concrete, steel and iron, and for replacement of bridge decks in rehabilitation (seismic repair, strengthen or retrofitting) to the construction of new ultra super-long bridge and building structures with less cost. In 1972, high strength polymeric material roof structure with the shape of an umbrella was manufactured via hand lay-up fabrication process and transported from the UK to be erected at the international airport of Dubai. In 1990s, it was replaced by advanced composites that were made with sophisticated glass fibre-reinforced plastics. Such advanced polymer composites with nanofillers (e.g., nanocarbons, glass fibre) are used for the development of building systems and building blocks using an automated construction system (ACS), which consists of a number of interlocking fibre-reinforced polymers (e.g., aramid) that can assemble into a large number of different efficient civil structures (e.g., 3D form) for use in the construction industry. Some examples of these ACS systems in the area of bridging engineering are Humber Bridge (1410 m span), Aberfeldy Bridge, Iron Bridge and the Bonds Mill Bridge from UK, and Gilman Bridge (450 m span), George Washington Bridge (1067 m span), Golden Gate Bridge (1280 m span) and Wickwire Run bridge from USA, Forth Road Bridge (1005 m span) from Scotland, and Tagus Bridge (1013 m span) from Portugal, and so on. These ACS components are cheaper with durability, light weight, low cost, speed of construction, ease of transportation, and they show superior mechanical properties (e.g., tensile, compression, shear strength) than iron, steel and stone. Therefore, such advanced carbon fibre-reinforced polymer (CFRP) composite materials are promising candidates in the future for the construction of ultra-super-long bridges. It is feasible to develop over 10,000 span stable super-long bridges using new concepts. A new concept of engineering that is used for nanoscale modelling of super-long bridges can be described in following sections.

Finite element models were created in Strand7 [3], and the results show that a maximum deflection of 8.3 m occurs under the combination of dead and wind (G+W) load, which slightly exceeds the AS5100 [11] limit of 6.3 m. Furthermore, a 32.4 m transverse deflection is found under the dynamic wind analysis. Maximum tensile stresses of 1154 and 1152 MPa are observed in the catenary cables and stayed cables, respectively, which are below the tensile strength of 1600 MPa of M55\*\*UD carbon fibre.
