Steel frame structures are highly susceptible to seismic loads attributed to the adverse infill-frame interaction. Although the traditional infill walls are well-acknowledged as nonstructural elements in buildings by most design standards and codes, their adverse effects are often underestimated or neglected in engineering practice. For instance, a combination of the high strength, stiffness, and brittleness of the infill can significantly affect the structural behaviors. Moreover, the adverse infill-frame interaction often makes it difficult to predict the actual structural behavior accurately.
Currently, there are three different methods used to address the problem of the infill-frame interaction. The first method uses different approaches, such as steel wire meshes, some types of fiber-reinforced polymers, and perforated steel plates to mitigate the vulnerability of the infill. While these interventions improve the seismic performance of the infill, they fail to effectively reduce the possible adverse effects of the infill-frame interaction. The second method attempts to eliminate or weaken the infill-induced detrimental effects by separating the infill and the surrounding frame using flexible joints around the wall-frame interface or cutting the corner of the wall panels. This could damage the infill and the frame. The third method divides the infill into different subpanels connected with sliding joints made of low shear materials to prevent damage to the infill and decrease its stiffness. The disadvantage of this method is the possibility of unfavorable cracks and crushing of the infill at the corner.
To overcome the limitations of the aforementioned methods, flexible materials can be used to separate the infill from the surrounding frame to avoid potential infill damage. The prefabricated horizontal panels require a low shear strength sliding mechanism to provide desirable results. This can be achieved using semi-rigid steel frames owing to their superior ductility and stiffness. To this note, Guangzhou University researchers: Professor Chao Zhang, Mr. Zhengzhong Li, Ph.D. candidate Weiyuan Huang, Professor Xuesong Deng, and Mr. Jianzhou Gao proposed two innovative semi-rigid steel frame systems infilled with prefabricated damping wall panels in wall-to-beam (DWSF-B) and wall-to-column (DWSF-C) connection types. The working principle and main features of the infill systems with both sliding joints and uncoupling mechanism were detailed. Additionally, the performance of the two systems in terms of seismic response was investigated via quasi-static tests and results compared with those of a bare steel frame (BSF). Their work is currently published in the Journal of Construction Steel Research.
The test results confirmed the suitability of the proposed wall panels in preventing the detrimental infill-frame interaction. Both DWSF-C and SWSF-B that were infilled with the prefabricated sampling wall panels were characterized with a remarkably larger deformation capacity of about 3.33% drift without significant infill damage. The infilled steel frames exhibited stable seismic behaviors akin to that of BSF with no infills, which included loading capacity, stiffness degradation, displacement ductility, and hysteresis curves. After yielding, their energy dissipation capacity was about 23.3% more than that of the BSF. Although the friction displacement of specimen DWSF-C was less than that of DWSF-B, the latter exhibited a more effective and controllable energy dissipation for which the low-strength motor could be replaced with an inexpensive alternative.
In summary, the research team successfully investigated the seismic performance of two innovative semi-rigid steel frames infilled with prefabricated damping wall panels. The remarkable seismic performance of the infilled steel frames that were comparable to those of BSF as well as high energy dissipation capacity suggested that prefabricated damping panels could be used as an additional safety feature for the steel frame and not major components of strength and stiffness. In a statement to Advances in Engineering, Dr. Chao Zhang explained their presented approach is more effective for mitigating the detrimental impact of infill-frame interaction and would contribute to the design of high-performance steel frame structures.
Zhang, C., Li, Z., Huang, W., Deng, X., & Gao, J. (2021). Seismic performance of semi-rigid steel frame infilled with prefabricated damping wall panels. Journal of Constructional Steel Research, 184, 106797.