Jesse D. Sipple

A new method is presented for finite element model (FEM) updating using frequency response functions and numerical sensitivities. The proposed method differs from methods currently in the literature by using numerical sensitivities to solve the inverse problem instead of analytical sensitivities. This method combines the usefulness of commercially available finite element modeling programs with advanced optimization algorithms to solve the inverse problem while requiring neither model reduction nor data expansion. The method is applied to several simulated test cases in which damage is detected and the usefulness of the method is shown. The method proved to be robust, stable, error tolerant, and successful in estimating unknown structural parameters using frequency response functions for FEM updating. Copyright © 2013 John Wiley & Sons, Ltd.

A baseline finite element model was developed for bridge management and calibration using nondestructive test data. The model calibration technique was evaluated on the Vernon Avenue Bridge over the Ware River in Barre, Massachusetts. This newly constructed bridge was instrumented throughout its construction phases in preparation for a static truck load test performed before the bridge opening. The strain data collected during the load test was used to calibrate a detailed baseline finite element model in an effort to represent the 3D system behavior of the bridge. Three methods of load ratings were used and compared: (1) conventional method, (2) conventional method updated by using NDT data, and (3) finite element model calibrated with NDT data.

Instrumentation, structural modeling, and model updating are incorporated into the design and construction process of a multi-span bridge to change the paradigm of traditional bridge design to a long-term bridge design. A continuous three span composite steel stringer bridge in Barre, Massachusetts was used as a pilot bridge. A monitoring system was installed in order to capture structural behavior during construction and into the service life of the bridge. Strain data from the steel girders was collected during the concrete deck pour. Two finite element models were created using shell/solid elements and frame/shell elements. Both computer model responses are compared with field strain measurements of the full scale bridge during the concrete deck pour. Both the shell/solid and frame/shell FEMs produced close estimates of the measured strain data. Modeling assumptions for boundary conditions and temperature effects play a major role in magnitudes of the analytical responses. In the future, truck load tests will be used for baseline model updating of the completed bridge. The structural model that reflects the actual bridge 3D system behavior can be used for load rating and overload permitting.

Nondestructive testing on bridges is a large part of a comprehensive structural health monitoring program. Another key component of structural health monitoring is finite element models for evaluation of the measured responses through model updating and parameter estimation. One method of nondestructive testing is a controlled static load test, where a pre-weighed truck is placed at predetermined locations on the bridge and the response is measured via strain, rotation, and deflection measurements. The location, wheel weights, and time at each location are precisely recorded during the entire duration of the load test. However, there is another load that can have more of an impact on the bridge response than applied static load, and that is thermal loading due to temperature change. It has been observed in three different load tests at Rollins Road Bridge in Rollinsford, NH that temperature effects mask the load applied to the bridge over the duration of the load test. These temperature effects either need to be corrected for, using an empirical correction, or included into the structural predictive model to get accurate results for use in a parameter estimation algorithm and model updating protocol to determine the structural health of the bridge.

In 2000, the Rollins Road Bridge in Rollinsford, New Hampshire was constructed with partial funding from the Innovative Bridge Research and Construction (IBRC) program administered by the Federal Highway Administration (FHWA). A requirement of the IBRC program is the use of high performance and innovative materials and instrumentation. This paper focuses on use of the collected data, from both strain and temperature sensors, to evaluate thermal performance of a CFRP-reinforced concrete deck. The sensor data will be evaluated based on its value in a long-term structural health monitoring program. The collected data will be compared with the predicted response for a finite element model created in SAP 2000. Also, a statistical analysis of the collected temperature and strain data will be presented for data quality analysis.