Tian-Yi Song

Temperature Field Analysis of SRC-Column to SRC-Beam Joints Subjected to Simulated Fire including Cooling Phase

Three tests were performed on steel reinforced concrete (SRC) column to SRC beam joints subjected to fire scenarios including heating and cooling phases, and this paper reports the thermal part of the test results as well as the spalling observations. As these joints were designed to investigate the behaviour of a big joint zone including part of the beams and columns connected, temperatures in the junction and areas certain distance away from the junction were measured during both the heating and cooling phases. The three tests tested the influence of heating time on the temperature distributions at various sections of the specimen. A three-dimensional finite element analysis (FEA) model is developed to calculate the temperature field of the SRC column to SRC beam joints. The predicted temperatures show good comparison with the test results. Based on the finite element analysis, the differences of the temperature distributions in the joint zone and the non-joint zone are analyzed and its influence to the structural fire safety design is illustrated. One important conclusion from this study is the necessity to include cooling phase in structural safety design because it is in the cooling phase that the majority of the specimen materials reached their peak temperature.

Performance of Steel-Reinforced Concrete Beam-to-Column Joints after Exposure to Fire

AbstractThis paper presents a numerical analysis on the postfire behavior of steel-reinforced concrete (SRC) column to axially and rotationally restrained SRC beam joints. A finite-element analysis (FEA) model was developed to simulate the reaction of the composite joints under an entire loading and fire phase, including ambient temperature loading, heating, and cooling with constant loads and postfire loading. For validation, the proposed modeling method was used to simulate the results of SRC joint postfire tests and SRC column and joint fire-resistance tests. The comparison demonstrates the accuracy of the proposed FEA model. Based on the validated FEA model, the failure modes of SRC joints with restrained beams were investigated, and the joint deformation and internal force development during the entire loading and fire phase were analyzed. Afterward, two important parameters, namely, residual joint strength index and residual stiffness index, were defined based on the joint moment versus relative rot...

Structural Behavior of SRC Beam-to-Column Joints Subjected to Simulated Fire Including Cooling Phase

AbstractThis paper presents the test results of three steel-reinforced concrete (SRC) columns to SRC beam joints under combined loading and fire. Simulated fires, including heating and cooling phases with different heating times, were applied to the lower part of the three composite joint specimens. Failure modes, concrete cracking, concrete spalling, and deformation development were observed or measured. The test results indicate that heating time affects the postfire residual bearing capacity significantly. A finite-element analysis (FEA) model was developed to simulate the response of SRC beam-to-column joints in whole loading sequences, including initial loading, heating, cooling, and postfire loading. Some key influencing factors, such as the creep of steel at high temperatures, slippage between the steel and concrete, and residual stresses in the H-shaped steel, were considered in the model. On the basis of the verified FEA model, the development of the rotation angle between the beam and column, wh...

Bond Behavior of Concrete-Filled Steel Tubes at Elevated Temperatures

AbstractExtensive studies have been conducted into the bond behavior in concrete-filled steel tubes (CFST) at ambient temperature. However, the bond behavior of CFST columns subjected to fire is st...