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The cyclic performance of structural steels after exposure to various elevated temperatures and cooling-down methods was experimentally investigated in this paper. Four types of frequently used structural steels were tested including Chinese mild steel Grade Q235, Chinese high-strength steel Grade Q345, and Chinese stainless steel Grade S304 and S316. A total of eighty specimens were prepared using three different heating–cooling processes before being subjected to cyclic loads. The post-fire basic features and hysteretic performances of the four types of structural steels exposed to various target temperatures (100–1000 °C), heat soak times (30 min or 180 min) and cooling-down methods (natural air or water) were recorded and discussed. The results show that all the tested structural steels prepared using different heating–cooling treatments exhibited proper ductility and energy dissipation capacity, while the heat soak times and cooling-down methods had a definite effect on their energy dissipation capacity; no Masing phenomenon was found in the tested structural steels. Finally, a set of skeleton curves were proposed for the four types of structural steels under cyclic loading based on the Ramberg–Osgood model, which could serve as the foundation for the seismic capacity evaluation of steel structures after a fire.

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Development of on-site fast detector using for waterproof membrane joint peeling strength has improved the waterproof membrane on-site construction quality evaluation level and construction quality decision capability. Detectors capabilities in two-dimensional movement and multi-angle detection fill the domestic gap. Verification test result of the detector shows that, the peeling force will fluctuate within certain scope with peeling of joints; the longer the membrane is stretched, the greater the error is; the error caused by angle deviation is about 7% and error caused by joint deviation is about 4%, and the test result satisfies the evaluation requirement on waterproof membrane joint peeling strength at construction site. The development of detector improves the construction quality, construction management and acceptance of waterproof membrane.

In order to study the seismic behaviors of fabricated steel frames with bolted beam-height adjustable steel beam-to-column connections (BHA connections), a six-story steel frame was designed to run pseudo-dynamic experiments. Experiments were first carried out with the steel frames with and without buckling-restrained braces (BRBs) under three different types of seismic records under 35 gal and 70 gal. Then the seismic records of EL_CENTRO amplified from 220 gal to 1,600 gal were loaded on the braced frame. Results showed that there was no detachment, sliding, or yielding detected in BHA connections. After BRBs were installed, the story drift and the top-story maximum displacement could easily meet the codes, and the structure was still working in the elastic stage under 620 gal. It could therefore be concluded that BHA connections have excellent seismic performance and they are suitable for application in fabricated steel frames. The braced frame using BHA connections has good lateral stiffness and energy dissipation capacity.