STAGED CONSTRUCTION AND TEMPERATURE ANALYSIS OF MULTISTOREYED BUILDINGS

Abstract

This study focuses on some of the important aspects in the analysis of multistoreyed buildings. The impact of staged construction analysis on the high rise buildings with ditThrent structural systems is studied. Buildings A and C having dual frame configuration with 20 and 30 storeys respectively as well as Buildings B and D having shear wall configuration with 25 and 35 storeys respectively are investigated for staged construction analysis. Staged construction analysis is carried out on four models using ETABS software and various aspects of construction sequencing in ETABS software arc studied. There is a marked variation in the stresses in case of staged construction analysis as compared to conventional one step analysis. The impact of staged construction is more pronounced in case of framed buildings as compared to shear wall systems. Another aspect from the point of view of serviceability of the building i.e. the impact of uniform temperature changes on the frame members of the building is studied and the variation of the resulting stresses and displacements along the various parts of the frame is investigated. Temperature analysis is carried out using ETABS software on four building frame models with varying lengths and heights and the resulting stresses are studied. The lengths of the building which can be allowed without providing expansion joints has been investigated It is found that the members at the lowermost storeys are affected the most due to the temperature changes and they should be designed for the additional stresses and displacements. Besides , the buildings A and B along with building E having special moment resisting frame configuration are compared in terms of their performance under the influence of seismic loads. Quite often, elastic analysis is not adequate to study the exact behavior of the structure. Performance based design which is a shift from the conservative design relies on nonlinear analysis to determine the actual building performance. Nonlinear static pushover analysis is carried out in ETABS vi 3 software by providing seismic ground motions in both the directions and their demand & capacity in terms of the displacements are compared. The FEMA 440 displacement modification method is used to determine the displacement demands of the building .Their ability to meet the seismic demands are studied and it is found that the buildings with dual frame configuration and with special moment resisting frames have more capacity than the shear wall systems to meet the seismic demand.