Meng Wang, Shunyu Zhang, Yi Sun, Kunpeng Dong
Replaceable low yield point (LYP) steel connection components were studied in their ability to withstand seismic loading and to be a solution to achieve a two-stage resilient design target. A two-stage resilient design target is outlined by a systems’ ability to function in damage control, along with its ability to be replaced after the event of earthquake. This allows for structures to be designed with local weakening and local strengthening points to be localize damage away from areas of critical connections. Different steel connection configurations were studied to investigate the extent to which the connections would be able to satisfy the two-stage resilient design target, along with validating the effect of the replaceable structural fuses. The proposed system uses simple connection methods without the need of additional energy dissipative elements that generally have more material, higher cost, and more complex connections. Numerical simulations of the different connection configurations were analyzed, along with a three-story steel frame structure with a reduced beam section. Static elastic-plastic analysis and nonlinear dynamic history analysis were also performed to study the seismic performance with the implementation of the proposed connection. Results of testing showcased promising bearing, deformation, and dissipation capacity of the LYP connection. Specific design connection configurations provided an improved structural fuse effect and desirable seismic performance.
System Concept
The proposed replaceable low yield point (LYP) steel connection components comprise of simple bolted connections with cover plates, T-stubs, and angle steels. The low-yield point steel provides high ductility, satisfactory energy dissipation capacity, and appropriate fatigue performance which contributes to the structural fuses’ ability to localize damage and allow for connections to be easily replaced. In this way, the proposed system is expected to control damage in expected regions to ensure ductility and ensure structural performance in the event of an earthquake. After an earthquake, the structural elements of interest that take the damage can be replaced and function can be recovered quickly to reduce repair costs. The different connection configurations of interest that were studied are as follows: widening of beam flange connection with cover plates and welded connection with reduced beam sections, along with bolted connection with T-stubs, cover plates, and angle steels.
Analytical Study, Results, and Discussion
Results indicates that steel frames with LYP steel connections provide sufficient load carrying capacity, along with desirable deformation and dissipation capacity. Widening beam flanges and reducing resistance capacity coefficient was also found to improve the structural fuse effect. The bolt steel frames specifically, when compared to welded steel frames, were also found to be better in carrying load, providing deformation capacity, and providing lateral resistance. This was determined by performing cyclic loading test and it also determined the LYP connections did indeed localize damage to protect the rest of the steel frame, especially at critical points. By localizing damage at non-critical areas, the fuses were able work to its full extent and were also found to be easily replaced in a bolted connection than a welded connection.
Reference
Meng Wang, Shunyu Zhang, Yi Sun, Kunpeng Dong (2021). “Seismic Performance of steel frame with replaceable low yeild point steel connection components and the effect of structural fuses,” Journal of Building Engineering