In steel shear wall, to avoid nonlinearization of boundary elements, capacity-based design is performed, which results in a significant increase in the amount of steel used in boundary elements. To reduce the boundary element steel, a semi-supported steel shear wall (SSSW) has been proposed and its efficiency has been proven in previous studies. In addition, it seemed that the use of concrete coating on steel plates could improve the strength and ductility of the SSSW system. For this purpose, an 8-storey building equipped with SSSW was first designed and its most critical opening was converted to a composite model (SSCSW) and its finite element model was produced. This model was presented against near and far fault cycle loading analysis and cyclic curve, capacity, dissipation energy, von Mises stress distribution and compressive damage of concrete. The results showed that Adding concrete to the SSSW model (converting the model to SSCSW) increased the initial in-plane stiffness by 4.5 times. Of course, this increase in stiffness is not unexpected because of the concrete on both sides of the steel plate. A very important point is that with the creation of cracks in the concrete, the stiffness quickly decreases and the slope of the post yielding area of the capacity curve is first negative and then experiences a slight increase due to the strain hardening of the steel plate. By adding concrete to the steel model, the ductility increases in two states near and far from the fault. The size of the increase is about 2.5 times and this increase does not depend much on the type of loading pattern. Of course, it should be noted that in the models of this article, the effects of steel plate tearing have not been modeled, so the ductility calculated in this study is with real capacity.The ductility is different and requires more accurate supplementary models to obtain a more comprehensive result. In terms of ultimate strength (peak of the cyclic diagram), the comparison of the results shows that regardless of the type of cyclic loading pattern, the calculated value for SSCSW is 28% higher than SSSW. It should be noted that the increase obtained as a result of pushover loading was estimated at 35%. For the pattern near the fault, the transformation of the model from SSSW to SSCSW led to estimate 67% more cumulative wasted energy. This value was about 73% for the far-fault protocol. This difference can be justified by the fact that in the close protocol, there was a significant increase in the loading cycle at the beginning of the protocol, and the issue of low cycle fatigue is excluded. While for the loading corresponding to the far fault, the gradual increase of the loading protocol is associated with low cycle fatigue and the input energy is depleted in more cycles. It is suggested that the designer pays special attention to the main elements (frame columns) in the near-fault protocol. In addition, considering that a part of the beam between the sub-column and the main column can somehow evoke the behavior of the link beam, it is suggested to evaluate the nonlinear behavior of this part of the beam in the future supplementary studies.
Article Type:
Original Research |
Subject:
Civil and Structural Engineering Received: 2023/09/2 | Accepted: 2024/02/28 | Published: 2024/08/31