Analysis of Concrete T-Beam Girders Supporting a Bridge Deck Slab Using Modified Strut-and-Tie Model

摘要

This paper focuses on the analysis and design method for the disturbed/discontinuous region of concrete bridge deck slab on wide T-beam girders with simplicity and accuracy using strut-and-tie model (STM). Strut-and-tie model in reinforced concrete designs that involve the utilizationof some basic tools including struts, nodes and ties is very powerful but indirect approach for analysing complex structures. The combined depth of the deck slab with the T-beam constituting a deep beam/corbel like geometry and the presence of empty space between the adjacent flanges of theT-beams providing a region of geometric discontinuity create a non-linear strain distribution. This enables the development of modified strut-and-tie model for the system of an existing Bridge. Full scale laboratory specimen of a lightly reinforced slab deck on wide T-beam test results iscompared with the strut-and-tie model results. The steel reinforcements obtained from the STM consisting of only shear reinforcement without transverse slab reinforcement do not exceed the reinforcements in the laboratory test specimen and withstand the imposed simulated vehicle wheel load.The girder web and flange stiffness represented by ties and struts in the system have substantial effect on the carrying capacity of the top slab. This would greatly reduce the amount of transverse steel reinforcement used for the slab deck. The model was developed using different configurationsand consequently, a much simpler and precise solution is obtained in which, an efficient ultimate capacity for the system is obtained.