Behaviour of peripheral t-shaped shear wall in framed tube structures in moderate seismic zones of Bangladesh

Abstract

Bangladesh is a small country with a high population density. Due to the demand for massive urbanization, more high-rise buildings need to be constructed in major cities. The framed tube structural system can be an effective framing technique for this case. This system comprises tightly spaced peripheral columns connected by deep spandrel beams. The total system works as a giant vertical cantilever. This study analyzes six reinforced concrete framed tube buildings of varying heights and peripheral configurations. The structures are categorized into two groups based on their peripheral members: (a) those with square columns and (b) those with T-shaped shear walls. The research examines three building heights, 20, 40, and 60 stories, corresponding to 81.5 m, 161.5 m, and 241.5 m, respectively. A regular plan configuration is considered for all building models to assess structural behaviour under various conditions. The reduced cost of columns, walls, and beams of square-shaped framed tube structures with peripheral T-shaped walls compared to the column is in the range of 3-8%. The shear lag factor for the ground floor is also reduced from 32% to 54% for structural configurations considered in the study. The concrete quantity with peripheral T-walls is reduced by 1-6%. The longitudinal reinforcement quantity is also reduced by 6-22%. The seismic performance level of buildings with peripheral T-walls is Immediate Occupancy (IO) for the hazard level corresponding to Service Level Earthquake (SLE), Design Basis Earthquake (DBE), and Maximum Covered Earthquake (MCE), while IO to Life Safety (LS) for the considered buildings having the peripheral columns. The plastic hinge formation of considered buildings with peripheral columns ranges from 2% to 14%, while those with peripheral T-walls are negligible. Therefore, for high-rise construction in Bangladesh, T-shaped shear walls in framed tube structures may offer better seismic performance and cost savings, making them an efficient alternative to traditional peripheral column systems.