Development of Design Parameters for Mass Concrete Using Finite Element Analysis

A finite element model for analysis of mass concrete was developed in this study. To validate the developed model, large concrete blocks made with four different mixes of concrete, typical of use in mass concrete applications in Florida, were made and monitored for their temperature and strain developments, and compared with the computed temperature and stress distributions from the finite element model. A parametric analysis was also conducted to determine the effects of various factors on the temperature distribution, induced stresses and the cracking risk. Investigation was also made on testing methods to measure the thermal and mechanical properties of mass concrete needed as input parameters for the finite element model. The findings from this study are as follows: (1) Results from the isothermal calorimetry test should be used for input for the heat generation function in the finite element modeling of concrete hydration; (2) Reliance on a limiting maximum temperature differential to control cracking in massive concrete applications should be supplemented with a suitable analysis to show that expected stresses will not exceed the strength of the concrete; (3) Adequate insulation should be used in conjunction with the usual formwork material to reduce the temperature differentials during the early age hydration of massive concrete; (4) A safety factor should be applied to the tensile strength values for concrete to guard against the initiation of micro-cracks; and (5) The current restrictions on maximum temperature imposed by state regulating bodies should take into consideration the type of cementitious materials that will be used in the concrete mix.