Plate Reinforced Composite Coupling Beams

This dissertation, "Plate-reinforced Composite Coupling Beams: Experimental and Numerical Studies" by Wai-yin, Lam, 林慧賢, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Plate-reinforced Composite Coupling Beams - Experimental and Numerical Studies Submitted by LAM Wai Yin for the degree of Doctor of Philosophy at The University of Hong Kong in October 2006 This thesis reports the results of experimental and numerical studies conducted on innovative plate-reinforced composite (PRC) coupling beams, designed with the objective of providing the construction industry with a feasible alternative coupling beam design that improves the structural performance of coupled shear wall structures under wind and seismic loading. The design of these coupling beams makes use of the composite action between structural steel and reinforced concrete (RC) by embedding a steel plate vertically into a conventional RC coupling beam. Shear studs were welded onto the steel plate surfaces in the beam span and the wall anchorage regions to enhance the plate/RC composite action. These studies build on the results of a previous experimental study conducted by the author on medium-length PRC coupling beams of span/depth ratio (l/h) 2.5. Three medium-length (l/h = 2.5) and three short (l/h = 1.17) PRC coupling beams were tested under reversed cyclic loading conditions. The results have demonstrated the effectiveness of both short and medium-length PRC coupling beams with properly designed plate anchorage in resisting large shear forces and withstanding large inelastic imposed deformations. It was found that shear studs in the wall regions would help to ensure ductile beam performance and desirable energy dissipation ability under seismic deformations, and that their absence would hinder the full strength development of short PRC coupling beams. A general pattern of bearing stress distributions with consistently large bearing stresses near the beam- wall joints and toward the ends of the plate anchors was also derived. i In order to extend the investigations to PRC coupling beams of different geometries and steel contents, so as to develop a comprehensive design procedure for the new type of coupling beams, the two-dimensional non-linear finite element analysis (NLFEA) program ATENA was employed. By introducing discrete bond and shear stud elements as the media for the plate/RC load transfers that allowed for interface slips, selected test specimens were first modelled and the reliability of the program in predicting the beam performances was verified. An extensive parametric study was then conducted on nearly one hundred PRC coupling beam models to investigate the effects of variations in span/depth ratios, reinforcement ratios and plate geometries on the load-rotation response under monotonically increasing loading. The internal load distributions were also investigated and the relationship between different force components on the plate anchors identified. These investigations indicated that if the walls were insufficiently reinforced or the plate anchorage was too short, the result would be the undesirable "strong beam - weak wall" phenomenon. Maximum allowable shear capacities and minimum required plate anchorage lengths were therefore proposed for PRC coupling beams to prevent early failure of wall piers. In the light of the experimental and the numerical observations, a bearing stress distribution model considering vertical and horizontal bearing forces was proposed for the plate anchors. An original and comprehen