Long-Term Field Monitoring of Lateral Loads in Semi-Integral Bridge Foundations

Jointless bridge designs have become increasingly common over the past several decades, both in the USA and worldwide. The increasing adoption of this alternative is largely due to the poor long-term performance of expansion joints and often prohibitive cost of joint maintenance. While integral bridges typically require flexible foundations to accommodate deck thermal movements, most transportation agencies do not require flexible foundations for semi-integral bridges. This is because, unlike integral bridges, the superstructure of a semi-integral bridge is not directly connected to the abutment and therefore is not expected to experience lateral loading. In this study, 1.5 years of data collected from the drilled shaft foundations of a semi-integral bridge in Texas is presented. This data indicates that semi-integral bridge foundations can also experience significant cyclic lateral loading. In this case, the largest bending moments were observed during the colder months of the year, when the superstructure experiences maximum shrinkage due to temperature decrease.