Deflection Analysis

In this paper, the most relevant aspects of Chapter 3.3, "Deflection Analysis," of fib Bulletin 114, are presented, emphasizing the original contributions and innovations incorporated in the fib Model Code for Concrete Structures 2020, with respect to previous versions. The three levels of approximation established for the computation of deflections in beams and one-way slabs, subjected to bending, are presented. The main characteristics, limitations, and range of validity of the developed methods are described, as well as the slenderness limits associated to the minimum necessary stiffness of the member. A simplified method for calculating deflections in two-way slabs is also presented, based on the extension of the zeta-method to two-way slabs using linear elastic analysis. In addition, deflections due to shear in thin-web reinforced concrete beams will be addressed, and two methods for the estimation of shear deflections will be described. Finally, some examples developed in the document will be briefly presented, which show the applicability and accuracy of the proposed methods.