Chapter 3 - Applied Loads and Stability of Steel and Steel-Concrete Composite Bridges

Abstract

The brief introduction of steel and steel-concrete composite bridges presented in Chapter 1 and the revision of the nonlinear material behavior of the main bridge components presented in Chapter 2 provide a useful background on bridges and the material behavior of the components of the bridges. It is now possible to detail applied loads acting on steel and steel-concrete composite bridges, which is highlighted in this chapter. This chapter presents different loads acting on railway and highway bridges and the stability of the bridges when subjected to these loads. The chapter starts by showing the dead loads of steel and steel-concrete composite bridges that are initially estimated for the design of bridges. Then, the chapter presents the live loads from traffic as specified in the American and European codes. After that, the chapter presents the calculation of horizontal loads and other loads acting on the bridges such as centrifugal forces, seismic loading, collision forces, and temperature effects. In addition, the chapter presents the load combinations specified in the current codes of practice to predict the worst case of loading for the calculation of different straining actions in the bridge components. Furthermore, different design approaches specified in the current codes of practice are highlighted in this chapter. Finally, the chapter addresses the main issues related to the stability of steel and steel-concrete composite plate girder and truss bridges such as buckling behavior of compression members, stability of thin-walled steel plate girders, lateral torsional buckling, and composite plate girder behavior. Once again, when highlighting the main issues related to the stability of the bridge components, it intends to review and present the issues based on the design rules specified in the current codes of practice, with particular focus on the Eurocode as an example. Overall, the author hopes that this chapter paves the way to the design examples of different bridge components presented in Chapter 4.