Performance of a novel slider device in multi-storey cold-formed steel modular buildings under seismic loading

Abstract

A 0.25-scale three-storey stacked modular steel structure, with a novel slider device used at each floor level, was built, and subjected to seismic biaxial base excitation in a series of shake table tests. The test results were reported in the literature by the first author of this paper, which showed that the proposed slider device and the modular steel structure performed well under seismic loading. This paper extends the work of previously reported shake table tests by developing a numerical model. The numerical model has been validated against the test results of the three-storey modular structure. The validated numerical model has then been extended to a six-storey structure consisting of six modules in total (one unit at each floor) with the same material, link, member and constraint properties as used in the three-storey building. The applied gravity loads for each module were also the same as that in the three-storey test structure. The six-storey structure has been subjected to a range of earthquake records from the El Centro, Delta, Kalamata, Chihuahua, Corinthos, Westmorland and Chi-Chi earthquakes that occurred in the past; all these records were scaled according to the loading standard (AS/NZS 1170) for a design site located in Wellington City, New Zealand. These further analysis results on six storey modular structure provide better indication of how a full-scale perfectly built multi-storey modular steel structure with the slider units behaves in practice. As revealed by the analysis results, the proposed sliding system in the six-storey modular steel structure can achieve all the desired performance objectives. When subjected to the scaled earthquake records applied in both the longitudinal and transverse directions, the modules slide in alternate directions at different floor levels within a maximum displacement defined by the 2.5% drift requirement and subsequently self-centered within a tolerance of 5 mm at the conclusion of the severe shaking. While sliding, all modules remain stable and were not prone to any collapse and soft-storey failure at lower levels. During the severe shaking, more than 80% of the seismic input energy is dissipated through friction and rubber hysteresis in the proposed system.