Tesis doctoral de Rolando Antonio Chacón Flores
A girder is deemed as being hybrid when it is fabricated with different steel strengths for the flange and web panels. This type of girder is popular as the girder yields a greater flexural capacity at a lower cost and weight compared to a homogeneous girder. extensive experimental, theoretical and numerical research on hybrid design can be found in the literature. Flexural capacity, shear resistance, instability and fatigue resistance of hybrid prototypes have been widely investigated in the last decades. Hybrid design has proven economically sound when used in continuous bridges. consequently, a myriad of bridges have been designed world-wide using a hybrid girder structural solution. A vast amount of these bridges have been erected by using the incremental launching method. The incremental launching method is particularly suited for the construction of continuous multi-span steel plate girder bridges. It consists of assembling and casting sections of the bridge superstructure in a stationary formwork behind an abutment in order to push a completed section forward with jacks along the bridge axis. this construction process implies that the reactions of the piers become moving concentrated loads acting in short lengths of the webs assembling the plate girders. During launching, the reactions of the piers are expected to be quite large, particularly when the cantilever reaches its maximum value. A concentrated force acting perpendicular to the flange of a steel girder is commonly referred to as patch loading. This type of loading usually induces a local failure of the web plate in the vicinity of the loaded flange. If the web panel is stocky, the failure mode is primarily dominated by yielding whereas whether the panel is slender, instability-related modes may occur. Patch loading phenomena has been widely analysed since the early sixties. Several failure mechanisms and critical buckling loads have been proposed throughout the last decades for the case of stiffened and unstiffened panels. despite the vast amount of research devoted to both topics, the research work that matches both subjects is scant. Consequently, a research work has been developed for the sake of bridging this gap. This thesis deals simultaneously with the patch loading and hybrid design fields. the core of the work is an experimental program on eight hybrid steel plate girders together with a vast amount of simulations performed on a properly validated numerical model. the work is focused on the assessment of the actual resistance predicted by en1993-1-5 provisions. The most remarkable results of the research work are pointed out. On the one hand, it is shown that the influence of the fyf/fyw ratio (namely, the hybrid grade) is negligible for girders with largely spaced transverse stiffeners and stiff flanges. On the other, it is shown that this influence can be significant if the transverse stiffeners are closely spaced and/or alternatively, the flanges are relatively flexible. At the end of the work, suggestions for considering these findings on design codes are provided.
Datos académicos de la tesis doctoral «Resistance of tansversally stiffened hybrid steel plate girders to concentrated loads«
- Título de la tesis: Resistance of tansversally stiffened hybrid steel plate girders to concentrated loads
- Autor: Rolando Antonio Chacón Flores
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 16/06/2009
Dirección y tribunal
- Director de la tesis
- Enrique Mirambell Arrizabalaga
- Tribunal
- Presidente del tribunal: Antonio ricardo Marí bernat
- darko Beg (vocal)
- ulrike Kuhlmann (vocal)
- Francisco Millanes mato (vocal)