Three-Dimensional Strut-and-Tie Analysis for Footing Rehabilitation

A 3D indeterminate strut-and-tie model is developed for the analysis of a footing system to explain the cause of cracking and to develop a rehabilitation solution. The performance predicted with the model, simulating the sequence of construction, is well correlated with the field observations. The prediction thus explains the cause of cracking and concludes that phased construction is its main source. From numerical prediction, posttensioning forces are recommended to close the existing cracks and to prevent new ones. In developing an approach to rehabilitating a cracked structure, the stiffness of the analytical model needs to be properly selected. For this reason, five different levels of stiffness are used to cover the lower and upper bounds for both cracked and uncracked situations. A 3D finite-element solid modeling is also conducted.