SOLUTION

WJE began with a comprehensive assessment of the garage, including section loss measurements and a multiyear plumbness survey. During probing, we discovered steel columns with nearly 100 percent section loss.

The structure was modeled in CSI SAP2000 and a detailed finite element analysis using Autodesk Simulation Mechanical. The finite element model of a typical moment connection served to locate points of high stress in the connection, particularly at the bolts and welds. In combination with the finite element model, the SAP model provided a better understanding of the behavior of the gravity system and the utilization ratios of the columns.

Columns with critical utilization ratios and severe section loss were selected to receive specialized repairs. Our repair design permitted direct transfer of concentrated girder flange forces without further pinching the columns. Our repair design also restored the cross-section of the heavily corroded columns. Braced frames were added to resist the lateral earth pressures imposed by the improperly designed retaining walls. Repairs were designed to minimize disruption to parking capacity. Our collaboration with the steel fabricator enabled just-in-time design and manufacturing of the shoring, as well as the permanent repairs to achieve the client’s goals.