Influenced Of Building Height And Seismic Zone On Foundation Design In Soft Soil

Abstract

The increasing demand for vertical expansion in urban areas has led to the proliferation of mid-rise and high-rise buildings, especially in regions where land availability is limited. In countries like India, which lies in a seismically active zone, the safety and stability of such structures under earthquake loading is of paramount importance. Among the critical aspects of structural safety is the design and performance of the foundation system, particularly when the building is situated on soft soil.

Foundation systems in such environments must be carefully engineered to resist both static and dynamic loads while minimizing differential settlement and tilt. Another important factor influencing seismic response is building height. Tall buildings (e.g., G+15) tend to have higher flexibility and longer natural time periods, making them more susceptible to resonance with certain seismic wave frequencies. This increased flexibility can result in larger story drifts and greater base shears during an earthquake. Conversely, low-rise buildings (e.g., G+6) are stiffer and may respond differently under similar seismic conditions.

This study presents the development of a STAAD Pro. Model for G+6 and G+15 buildings in seismic zones III and V with soft soil conditions requires a detailed approach focusing on seismic design and soil structure interaction. The increased height (G+15) and higher seismicity (Zone V) combined with soft soil demand and design approach, particularly a Dyanamic Analysis Method like Response Spectrum Analysis.Model the beams and columns as frame members. The G+15 building will require greater precision in modeling due to its height. Assign appropriate material properties and section properties. Model the supports as fixed initially.However,since the soil is soft, the supports as spring supports initially. The seismic load varies significantly between the specified zones and building heights.Sesmic zone factor for Zone II -0.16 and Zone V -0.36.For G+15 zone V, using a Special Moment Resisting Frame with Response Reduction Factor R-5 is strongly recommended to ensure ductility and better seismic performance.