Serviceability model for concrete frames Part I: Description of the model and application examples

Abstract

A general method for instantaneous and time-dependent serviceability analysis of plane concrete frames is presented. The methodology is based in an extension of the classic matrix formulation for bars. The main aspects influencing the behavior of the structural concrete are considered: cracking, creep, shrinkage or prestress losses. To simulate the effect of cracking an smeared model (developed in Part II) based on the modification of the tensile branch of the concrete stressstrain relationship is adopted. The general approach considered permits the application to different materials and constitutive laws. Sequential construction (sectional and structural), incorporation of reinforcement, consideration of the loads history, placing and removing shores, and restraining or releasing in boundary conditions are considered. Some examples are included to highlight the capabilities of the model.