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This paper presents results from an experimental study on the effect of temperature on bond strength of I-shaped steel and concrete. Eleven concrete encased steel (CES) specimens were tested by home-made fire test furnace to evaluate bond strength at various constant high temperatures (20°C600°C). The test results showed that: (1) the trend of the bond-slip curves at high temperatures were much similar to that at room temperature. Compared with room temperature specimen, the ultimate bond load and the residual bond load of specimens at high temperatures were significantly decreased. The specimens with the higher temperature had the less ultimate bond load and residual bond load. (2) In the descending stage, the P-S curve of the specimens with higher temperatures had more flat slope. The P-S curve of the specimens at the temperatures higher than 250°C had invisible descending stage. The ultimate bond load of the specimen at 600°C left with only about 5% of that at room temperature. (3) The ultimate slippages (i.e. the slippage at the ultimate bond load) of specimens at high temperatures were larger than that at room temperature, and varied from 2 to 5 mm. (4) The calculation formulas of ultimate bond load, ultimate slippage, and residual bond load at different temperatures were presented, the constitutive equations of bond-slip at different temperatures were obtained, which will provide a reference for the fire-resistant design of concrete encased steel columns. [ABSTRACT FROM AUTHOR]

To investigate the shear capacity of indirectly loaded reinforced concrete beams under and after fire exposure, load tests were conducted on eight full-scale specimens exposed to fire testing in a furnace chamber, and the effects of additional transverse reinforcement in the junction region between the primary and secondary beams on the shear capacity, fire resistance, failure modes and deflection were analysed. The results indicate that the slopes of the diagonal cracks in post-fire tested reinforced concrete beams without additional transverse reinforcement were shallower than those of a similar reference beam not exposed to fire, and that the ultimate capacities of reinforced concrete beams with additional transverse reinforcement decreased obviously after fire exposure. However, beams with additional transverse reinforcement exhibited increased fire resistance times and reduced strains in their reinforcement, indicating the benefit of conservatively providing such reinforcement. The findings of this study are expected to provide a reference for the improved fire-resistant design of indirectly loaded beams. [ABSTRACT FROM AUTHOR]