Seismic life-cycle cost assessment of steel frames equipped with steel panel walls

The earth crust remains dynamic with plates suddenly slipping past each other, consequently releasing energy and shaking the ground as a result. This occurrence often spells disaster whenever it occurs as lives, livelihoods and property are often lost/destroyed. Current urban developments call for densification of the available land by championing for vertical developments. Engineers globally have taken up the task confidently and numerous multi-story structures have been developed. Steel has often been the preferred material for such developments. To date, mitigation of seismic damage in new and existing building structures remains an important yet challenging topic in the field of earthquake engineering. Bare steel frame has only one defense against earthquakes, and it can collapse due to the failure of certain beam-to-column joints. Technically, there are 3 measures that can be executed to save such steel structures. Of the three, addition of lateral resistance components to enhance the seismic capacity of buildings presents not only a feasible idea easy to implement, but also an economically acceptable approach to addressing seismic deficiencies in high-rise steel structures.

For instance, the steel panel wall (SPW) has been proposed for strengthening mid-rise and high-rise steel frame buildings. In evaluating the SPW for reducing the damage cost of steel frame buildings, the life-cycle cost analysis (LCCA) approach was used to assess the final cost of the structure over the lifetime considering both increased initial cost and reduced damage/repair cost. Regardless, the doors are still wide open for development of other approaches and for such evaluation purposes. In this view, researchers from the Central South University, China: Dr. Liqiang Jiang, Professor Lizhong Jiang and Dr. Yi Hu, in collaboration with Professor Jihong Ye at the China University of Mining and Technology and Dr. Hong Zheng at the Chang’an University in China developed a new seismic life-cycle cost (SLCC) assessment method for steel frames equipped with steel panel wall (SPWF) structures. Their work is currently published in the research journal, Engineering Structures.

In their approach, cost-based seismic fragility analysis was proposed instead of the performance-based seismic fragility analysis, and the uncertainty propagation from failure probability to damage cost was considered. The technique considered the initial cost of the bolt-connected SPWs and the long-term economic consequences and benefits from the SPWs. Finally, a simplified method was proposed to directly describe the relationship between the SLCC and structural parameters.

The authors reported that the relationship between the ratio of seismic failure cost to initial cost η and 1/β could be simplified by a power function, and the relationship between the A-parameter in the power function and the servicing time could also be simplified by a new power function. Moreover, various advantages that could be ripped from the proposed approach were reported.

In summary, the study presented a seismic life-cycle cost assessment method based on cost-based seismic fragility analysis and seismic risk assessment procedures. The proposed technique involved calculation of the structural responses, damage states and induced costs, aleatory and epistemic uncertainties, and seismic risk. Remarkably, the presented technique was implemented in 12-storey SPWF buildings with the aim being to quantify the effectiveness of the proposed SPW in reducing the seismic life-cycle cost of steel frame buildings. In a statement to Advances in Engineering, the authors highlighted that the presented idea offered a new method for future engineering practice and structural optimization.