ABSTRACT
The study investigates the fire performance of Composite Steel Truss in Concrete (CSTC) beams through experimental testing and numerical analyses, aiming to develop design methods for predicting bending and vertical shear resistance under fire conditions. CSTC beams, composed of concrete-encased steel lattices with an exposed bottom plate, were tested in fire scenarios to understand their high-temperature behavior. Two full-scale fire tests and over 100 heat transfer analyses informed the development of thermal and thermomechanical FE models, leading to analytical expressions for reinforcement temperatures and effective concrete section estimation. A step-by-step design method for bending resistance was proposed. Vertical shear resistance, influenced by web diagonals and concrete struts, was examined through pull-out tests and companion simulations. The proposed HTA-based design approach, calibrated against experimental and numerical data, provides a generalized and reliable method for determining the vertical shear resistance of CSTC in the fire situation.
