Nondestructive testing for design verification of Boston’s Central Artery underpinning frames and connections

Abstract

Prior to the demolition of the Boston Central Artery viaduct in March 2004, a research team implemented a programme of nondestructive testing for design verification of two structural steel highway bents. The tested support bents were used to underpin the original Interstate-93 Central Artery viaduct during construction of the new cut-and-cover tunnel below it. Upon opening of the tunnels, traffic was rerouted from the elevated viaduct to the new tunnel, and the demolition process of the viaduct structure began. Two of the remaining support bents of the underpinning structure were fitted with sensors (strain gages, tiltmeters, slide wire potentiometers, and a 50 kip (222.4 kN) load cell) and loaded by a 50-ton (444.8 kN) crane. The measured structural response was compared to the expected response from finite element structural models, and the structural models were updated using parameter estimation techniques for design verification. Using as-built information, considering original design assumptions, and parameter estimation simulation results, the researchers selected a set of sensor types and locations for the nondestructive field test. Key design parameters of the underpinning finite element model such as connection stiffness values were successfully estimated using structural parameter estimation. As a result, the updated structural response correlated well with the collected nondestructive test data.