PREDICTING THE CRACK WIDTH OF REINFORCED CONCRETE STRUCTURAL MEMBERS USING THE SMEARED CRACK MODEL AND LAYERED SHELL ELEMENTS IN GENERAL-PURPOSE FINITE ELEMENT PACKAGES

This study investigated the method for calculating the crack width of reinforced concrete structural members using layered shell elements in general-purpose finite element packages. The calculation was based on the smeared crack model. The theoretical background was discussed first. The classical crack band theory proposed by Bazant and Oh is only suitable for plain concrete structural members, with significant localization effect resulting in possible mesh dependency. When the crack band theory is extended to reinforced concrete structural members that are commonly used in engineering practices, considering the characteristics of distributed multi-crack pattern, the crack band width should be modified as the average crack spacing so that the calculation results are independent of the element mesh. Based on the theoretical background, a calculation procedure for calculating the crack width of reinforced concrete structural members using the smeared crack model and layered shell elements in general-purpose finite element packages was proposed. In this procedure, the average crack spacing is the most critical parameter that closely relates the strain concept in the finite element analysis with the crack width concept in engineering design. Finally, the cracking behavior of a concrete slab in a simply supported composite beam subjected to a negative moment was analyzed as an example. Critical issues including the mesh sensitivity, solutions to the numerical convergence difficulty caused by large softening modulus, and the dominant role of the average crack spacing etc. were verified and discussed.