Deflection Prediction for Reinforced Concrete Structures Under Service load


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Title: Deflection Prediction for Reinforced Concrete Structures Under Service load

Author(s): N. Mickleborough

Publication: Special Publication

Volume: 203


Appears on pages(s): 131-142

Keywords: cracking; deflection; ductility; effective stiffness; reinforced concretes; serviceability; tests

Date: 8/1/2001

To determine the structural response to service load of reinforced concrete structures and structural components, the consequences of cracking on the effective stiffness must be considered. Usual methods to determine structural response of tall reinforced concrete structures involve codified simplifications and global reductions in effective stiffness of the beams and columns. Previous work (I), (2) has developed a method to determine the effective stiffness of members within a structure which can be extended to the analysis of structural frames. This method considers the consequences of cracking in tall buildings using a member element stiffness reduction model. The model is based on the ratio of the area of the member moment diagram where the applied moment exceeds the cracking moment, to the total area of the moment diagram. From this ratio the effective stiffness of the member can be estimated. A practical cracking analysis system has been established by integrating the proposed stiffness reduction model with an iterative algorithm and the commercial package of a linear finite element analysis. With this procedure, each member can be assigned their appropriate stiffness as a function of the applied load. and the response of the structure to service loading determined. Verification of this method of analysis, and its application to structural frames, has been achieved from and extensive experimental program considering flexural members. shear wall members and large-scale structures.