Transversal Shear Force in the Shear Connection of Twin-Girder Composite Bridges – Open vs. Semi-Closed Bridge Cross-Sections

Steel concrete composite (SCC) structural system has been commonly used both in the buildings and in the bridges because of the advantages it associates when compared to its counterparts such as RC and steel structures. A typical SCC girder consists of a concrete element placed over a steel element. The effectiveness of this composite system is characterized by the type of connection that exists between the two connecting elements. More commonly shear stud connectors are used to connect the two elements. If the shear studs are infinitely rigid, then it brings about full composite action, on the contrary there is no composite action if the studs are not used, between the two connecting elements. It has been observed that generally the composite action exists somewhere between the full composite action and the no composite action, and is called the partial composite action or the partial interaction. More often the partial composite action is overlooked during the design of SCC girders, and the girder is designed assuming that there exists full composite action, because of the complexities in the analysis incorporating the partial composite action. This might lead to the serviceability issues in the SCC girders. Keeping this in mind the present work has been carried out to understand the significance of the partial interaction in SCC girders. In the present work, a comparative study has been made between the available analytical model and the numerical model. Numerical modeling is performed by using commercially available tool such as SAP2000. The main objective of this work is to bring out the relative significance of the partial interaction with respect to the full composite action, with the help of parametric study. Here, the parametric study has been carried by considering various design parameters, such as, span length, degree of shear connection, cross section geometry of steel girder and concrete slab. It is observed that there is significant increase in deformations of the SCC girder, on account of the partial interaction. The results of the numerical model and the analytical model are in good agreement.

Experiments are being performed on a 0.4 scale model of a steel girder bridge superstructure with a reinforced concrete deck to investigate means of improving the seismic performance of typical slab and girder bridges. During the early stages of experimentation, the need to understand the influence of composite action became apparent. Accordingly, an analytical study was undertaken. The first of several finite element analyses on a typical continuous four-span, four-girder bridge model assumed shear studs along the entire length of the bridge to provide full composite action. A second model omitted the shear connectors in the negative moment regions, a common design practice to avoid fatigue concerns in the top flange. It was found that the shear connectors in the fully composite model were sufficient to ensure composite action when subjected to transverse loading and provided an adequate load path through the superstructure and into the substructure. However, the lack of shear connectors in the negative moment regions caused the load to be transferred into the steel girders at the points of contraflexure, resulting in damage to these girders and inadequate formation of the ultimate limit state in the columns. The lack of composite action was also found to change the distribution of transverse shear forces in the cross frames, which is important for design of the end cross frames. Making the top chord of the cross frames composite with the deck, at the column bent locations, proved effective in minimizing damage to the superstructure.

This chapter presents an experimental and modelling investigation into modular composite beam structures using web-flange fibre reinforced polymer (FRP) and steel for building floor construction. The modular FRP slabs are formed from adhesively bonding pultruded box profiles (i.e. square hollow sections) sandwiched between two flat panels. They are then connected via adhesive or one-sided bolted connections to steel beams to form a composite system. Two different fibre (pultrusion) configurations are investigated in this chapter: flat panel pultrusion with direction either parallel or perpendicular to the box profiles. Composite beams were tested under four-point bending and evaluated for bending stiffness, load-carrying capacity, and the degree of composite action within the FRP web-flange sandwich slab and that provided by the shear connections. All the composite beams showed ductile load–deflection responses, with yielding of the composite beam commencing prior to failure of the FRP slabs. Furthermore, adhesive bonding provided full composite action, but the novel bolted connections with a certain spacing provided either full or partial composite action, dependent on the pultrusion configuration of the FRP slab. An analytical procedure is also developed to evaluate the bending stiffness and load-carrying capacity of the composite beams. Finite element analysis was further employed in this chapter, showing good comparisons to the experimental results.

This paper presents an experimental and modelling investigation into modular web-flange fibre-reinforced polymer (FRP)-steel composite systems for use in building floor construction. The modular FRP slabs are formed from adhesively bonding pultruded box profiles sandwiched between two flat panels. They are then connected via adhesive or novel bolted connections to steel beams to form a composite system. Two different fibre (pultrusion) configurations are investigated in this paper: flat panel pultrusion with direction either parallel or perpendicular to the box profiles. Composite beams were tested under four-point bending and evaluated for bending stiffness, load-carrying capacity, and the degree of composite action within the FRP web-flange sandwich slab and that provided by the shear connections. All the composite beams showed ductile load–deflection responses, with yielding of the composite beam commencing prior to failure of the FRP slabs. Furthermore, adhesive bonding provided full composite action, but the novel bolted connections with a certain spacing provided either full or partial composite action, dependent on the pultrusion configuration of the FRP slab. Finally, an analytical procedure is presented to evaluate the bending stiffness and load-carrying capacity of the composite beams. Finite element analysis was also employed in this study, showing good comparisons to the experimental results.

This paper develops a new type of shear connection for steel-concrete composite bridges using Ultra-High Performance Concrete (UHPC) as the connection grout. The UHPC-grout strip shear connection is fabricated by preforming a roughened slot in the concrete deck slab, welding an embossed steel rib longitudinally to the upper flange of the steel girder, and casting the strip void between the slot and the steel rib with UHPC grout. The structural performance of the new connection was validated by two sets of experimental tests, including push-out testing of shear connectors and static and fatigue testing of composite beams. The results of push-out testing indicate that the UHPC-grout strip shear connection exhibits a significant improvement of ductility, ultimate capacity, and fatigue performance. The interface shear strength of the UHPC-grout strip connection is beyond 15 MPa, which is about three times that of the strip connection using traditional cementitious grouts. The ultimate capacity of the connection is dominated by the interface failure between the embossed steel and the UHPC grout. The results of composite-beam testing indicate that full composite action is developed between the precast decks and the steel beams, and the composite action remained intact after testing for two million load cycles. Finally, the trail design of a prototype bridge shows that this new connection has the potential to meet the requirements for horizontal shear.

<p>Box-girder composite bridges using prefabricated full-depth deck panels allow modular construction, greatly minimizing traffic impacts as well as providing longer span capability and better aesthetics when comparing with conventional plate girder systems. Shear stud clusters embedded in shear pockets are usually used to create composite action between concrete deck slabs and steel box girders. For accelerated bridge construction, it is advantageous to extend the spacing between the stud clusters. As a result, concerns have been raised about the effectiveness of composite action between the precast panels and the supporting girders. In this study, four composite box girders with a length of 5400-mm and a height of 380-mm were fabricated. The slab and the steel box were made composite by using closely-spaced studs over the full span length of beam. The arrangement of stud clusters of beams is respectively 2×3@400mm, 2×3@600mm, 2×2@800mm and 2×3@800mm, resulting in different degree of shear connection between 0.65 and 1.22. The specimen beams were tested to failure under two-point concentrated loads. It can be concluded from the experimental study that: (1) Shear stud clusters in the composite girder design can provide the necessary shear connection at the interface of steel box- girders and precast concrete slab bridge construction to achieve full composite action; (2) The degree of shear connection has little influence on the elastic behavior of composite box girders, and it has limited influence on the ultimate bending capacity; and (3) The testing has proven that full composite action between precast concrete panels and steel box girders can be achieved when the degree of shear connection is not less than 0.7.</p>

Chapter 2 - Nonlinear Material Behavior of the Bridge Components

Nowadays, in prefabricated composite construction, composite action between steel beam and concrete slab is often achieved with positioning of shear connectors in envisaged openings of concrete slabs. Prefabricated concrete slabs are used for composite steel-concrete buildings and bridges, both for the construction of new structures and for renovation of existing ones, significantly reducing construction time. Development of different types of shear connectors represent alternative solution to the traditionally used headed studs, considering their shear resistance, stiffness and ductility. New types of shear connectors tend to reduce the construction time and overall construction cost. Mechanically fastened shear connectors represent a viable alternative to headed studs, considering their fast installation process and shear resistance. X-HVB shear connectors are attached to the steel beam with two cartridge fired pins. The first step towards extensive implementation of X-HVB shear connectors in composite construction is to understand their behaviour through experimental investigation. Results of the push-out tests, in accordance to
\nEurocode 4, with X-HVB 110 shear connectors positioned in envisaged openings of prefabricated concrete slabs are presented in this paper. The experimental investigation comprised three different specimen’s layout. Group arrangement of X-HVB shear connectors in envisaged openings included specimens with minimal recommended distances and specimens with reduced distances between connectors in both directions. Influence of different installation procedures on overall behaviour of the connection is presented, as well as the orientation of shear connectors relative to the shear force direction. Influence of variations is characterized in terms of failure mechanisms, shear resistance and ductility.

At present, the study of the torsion performance of the steel-concrete composite bridge with open sections are usually simplified to study the torsion performance of single-girder steel-concrete composite bridge added the influence of transverse vehicle distribution. Due to the existence of transverse connections between the bridge girders, the overall torsion performance of double-girder composite bridge is different from that of single-girder composite bridge. Therefore, it is necessary to study the effect of different forms of the connections on the torsional properties of the double-girder composite bridge through experiments. In this paper, three double-girder steel-concrete composite model bridges are designed to study the effect of different forms of transverse connections and the effect of different shapes of steel webs on torsional properties of composite bridges.

The bond and friction of the interface between concrete slab and steel beam can affect the shear force values of the shear studs widely-used in steel-concrete composite bridge structures. The complex bond-slip relationships of the interface make the nonlinear finite element analysis become difficult. In this paper, computer aided method was proposed for the analysis of steel-concrete composite bridge with interfacial bonding and friction considered. A new type of cohesive zone model with the cementing bond and friction included is applied to simulate the complex interfacial behavior between concrete slab and steel beam. Cohesive interface element was then developed through the user subroutine in ABAQUS software. Then a continuous steel-concrete composite beam bridge model was analyzed with the proposed method. Load-deflection relationships of the steel-concrete composite structure, interfacial slips, interfacial shear stresses, and shear force of shear connectors were investigated. Results showed that the bond and friction of the interface between concrete slab and steel beam can affect the shear force distributions of the shear connectors. Numerical analysis method proposed in this study can be used for the analysis and evaluation of the shear connectors used for steel-concrete composite bridge structures. Results of this study can be further applied to intelligent testing and monitoring. It can provide theoretical support for the data analysis of intelligent infrastructure operation and maintenance.

Chapter 2 - Nonlinear material behavior of the bridge components

Design of shear connection in composite steel and concrete bridges with precast decks

Chapter 1 - Introduction

This article discusses the non-linear analysis and design of highway composite bridges with profiled steel sheeting. A three-dimensional finite element model has been developed for the composite bridges, which accounted for the bridge geometries, material non-linearities of the bridge components, bridge boundary conditions, shear connection, interactions among bridge components and bridge bracing systems. The simply supported composite bridge has a span of 48 m, a width of 13 m and a depth of 2.3 m. The bridge components were designed following the European code for steel–concrete composite bridges. The live load acting on the bridge was load model 1, which represents the static and dynamic effects of vertical loading due to normal road traffic as specified in the European code. The finite element model of the composite bridge was developed depending on additional finite element models, developed by the author, and validated against tests reported in the literature on full-scale composite bridges and composite bridge components. The tests had different geometries, different boundary conditions, different loading conditions and different failure modes. Failure loads, load–mid-span deflection relationships, load–end slip relationships, failure modes, stress contours of the composite bridge as well as of the modelled tests were predicted from the finite element analysis and compared well against test results. The comparison with test results has shown that the finite element models can be effectively used to provide more accurate analyses and better understanding for the behaviour and design of composite bridges with profiled steel sheeting. A parametric study was conducted on the composite bridge highlighting the effects of the change in structural steel strength and concrete strength on the behaviour and design of the composite bridge. This study has shown that the design rules specified in the European code are accurate and conservative for the design of highway steel–concrete composite bridges.

This study aims to show, the strength of steel beam-concrete slab system without using shear connectors (known as a non-composite action), where the effect of the friction force between the concrete slab and the steel beam has been investigated, by using finite element simulation.
 The proposed finite element model has been verified based on comparison with an experimental work. Then, the model was adopted to study the system strength with a different steel beam and concrete slab profile. ABAQUS has been adopted in the preparation of all numerical models for this study.
 After validation of the numerical models, a parametric study was conducted, with linear and non-linear Regression analysis. An equation regarding the concrete slab-steel beam system strength in non-composite action has been pointed out. Where the actual strength of the beam without using shear connectors has been located in between the full composite action and non-composite action. However, partial-composite action has been noted, due to the effectiveness of friction force which makes the beam behave as composite before the slip occurs.