REDUCING THE STEEL CONSUMPTION OF A LONG-SPAN AUTOMOBILE CENTRE FRAME IN A SEISMIC REGION

Abstract

Steel frames account for a major share of the load-bearing cost of long-span commercial buildings in seismically active regions, and the sources of excess steel consumption in such projects remain poorly documented on the basis of as-built design data. The study quantifies feasible reductions of steel consumption for a two-storey automobile centre with a 17 m column-free showroom erected in Tashkent region, Uzbekistan, with seismic intensity 7. A plane-frame numerical model of the transverse frame was developed in Python, checked by 25 automatic verification tests, cross-validated with an independent finite element library with agreement within 0.01%, and verified against the design force envelopes, the deviations being 7-12% for the moments and shears of the governing members and within 13% for the column axial forces. Seismic action was evaluated by the response spectrum method of the national code KMK 2.01.03-19 for each block separated by antiseismic joints. The as-built frame consumes 224.4 t of steel, or 55.9 kg/m² of the total floor area. The design base shear equals 3.7-4.5% of the block weight, whereas the interstorey drift of the worst service-block frame reaches 1/189 against the code limit of 1/200, so stiffness governs the frame proportions. Five measures were assessed: section resizing saves 33.8 t, lattice girders of cold-formed hollow sections save 22.4 t, composite action of floor beams saves 16.5 t, a braced service block saves 8.4 t, and the higher steel grade S345 brings no saving. A consistent combination of the measures reduces consumption by 47.3 t, or 21.1%, to 44.1 kg/m². The results support stiffness-oriented design of long-span buildings in areas of moderate seismicity.Keywords: steel frame, earthquake resistance, response spectrum method, interstorey drift, lattice girder, composite beam