Seismic Behavior Of Cold-Formed Thin-Walled Steel Reinforced Concrete Shear Walls

The shear walls of cold-formed thin-walled steel reinforced concrete (CTSRC) have lately emerged in modern residential building structures. The present study was focused on the seismic performance of the CTSRC shear walls, and the primary investigations and researching findings were outlined as follows.(1) The full scale quasi-static tests were performed on four shear walls and one 3-story model structure, respectively. The effects of the structural configurations, cold-formed thin-walled steel and the steel meshes on the seismic behavior of CTSRC structures were analyzed. It was shown that CTSRC structures can work efficiently to meet with the seismic requirements of multi-storey buildings. Recommendations for the design of multi-storey CTSRC composite structures were suggested.(2) Twelve shear walls that were designed to be high flexible resistance and low shear resistance were tested subjected to quasi-static cyclic loadings. Insights were gained into the critical structural configurations and design parameters in regard with the improved seismic performance. Laboratory observations revealed that the CTSRC shear walls started to fail with the vertical visible cracks around the cold-formed thin-walled steel reinforcements and the whole shear wall was eventually split into several wall columns. The observed failure mechanism of CTSRC shear walls should be considered a non-brittle one that helps improve the seismic performance. It was concluded that the shear resistance of CTSRC shear walls decreased with the increase of shear span ratio, and increased with more horizontal rebar. Results also showed that the ductility can be enhanced by more horizontal steel rebar, and cold-formed thin-walled steel had little effect on the performance of the CTSRC shear walls.(3) An analytical approach for the prediction of shear resistance of CTSRC shear walls was developed, in which the slip between different wall columns were considered and incorporated into the softened strut-and-tie model. The analytical predictions and test results are in good agreement.(4) A tri-linear relationship between lateral shear force and displacement was proposed to describe the hysteretic behaviour of CTSRC shear walls. The hysteretic behavior of the CTSRC walls is simulated with proposed skeleton model and Lu-Qu's hysteretic model, and the analytical results agreed well with the test results.(5) Based on the present experimental study, the flexural behavior of CTSRC walls was analyzed which led to a calculation method proposed for the prediction of the flexural resistance of CTSRC walls.(6) The design recommendations for the CTSRC shear walls in high rise buildings were proposed.