COMPARATIVE STUDY OF MODIFIED CONSTRUCTION STAGE ANALYSIS AND CONSTRUCTION STAGE ANALYSIS FOR RC BUILDINGS

Abstract

A significant difference is found in axial shortening of vertical members in tall concrete buildings when analyzed by Construction Stage Analysis considering the effect of creep and shrinkage as compared to the conventional One Step Analysis method. In Construction Stage Analysis the self-weight of structural members, and a load of brick walls along with floor finishing load, gets added sequentially as construction is carried out. In addition to the above loads, construction loads such as the weight of formwork, the weight of wet concrete, staking of materials, and other construction loads of men and machines get imposed on the structure during construction. Also, stagewise reduction of load due to removal of formwork, material staking, and other construction loads of men and machines should also be considered during the analysis with the Construction stage method. The axial shortening of vertical members of RC buildings was analyzed by the Conventional one-step method, Construction Stage method, considering self-weight along with brick wall and floor finishing load as sequential loads. Modified Construction Stage method-in which in addition to self-weight, brick wall, and floor finishing load, above mentioned all loads that appear during construction, were added, and removed sequentially in the analysis, by taking 20,30, and 40 floor RC building models. Modified CSA gives 2.068% to 20.56% lesser axial shortening in comparison to the CSA method. The study also concludes that the difference of axial shortening between Modified CSA & CSA increases from first to a certain floor, after that it reduces till top floor.