Jesse D. Sipple

Instrumentation, Nondestructive Testing, and Finite-Element Model Updating for Bridge Evaluation Using Strain Measurements

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 bridgewas 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. DOI: 10.1061/(ASCE)BE.1943-5592.0000228.

Full-Scale Bridge Finite-Element Model Calibration Using Measured Frequency-Response Functions

AbstractA frequency-response function–based parameter-estimation method was used for finite-element (FE) model calibration of a full-scale bridge using measured dynamic test data. Dynamic tests were performed on the bridge to obtain measured frequency-response functions. Data quality was ensured by comparing measured data with the FE model and removing erroneous data. A coherence data selector was developed to remove the noise-contaminated portions of the measured frequency-response functions. An unrefined FE model was created using design information for the geometry and structural parameters. This model was improved to a refined model by using concrete cylinder property data, as-built drawing geometry, and the addition of components that participate in the dynamic response of the bridge. Simulations were performed using the model to ensure both observability and identifiability of structural parameters. The model of the bridge was then calibrated successfully using measured frequency-response functions....

Objective Load Rating of a Steel-Girder Bridge Using Structural Modeling and Health Monitoring

AbstractThe future of highway infrastructure in the United States is at a critical junction. Nearly one-third of U.S. bridges are nearing the end of their design life, and one in ten bridges is categorized as structurally deficient. While the design and construction of the next generation of U.S. highway bridges is underway, existing bridges must be maintained through proper inspection and load rating. This paper proposes an objective load rating protocol that takes advantage of a shift in the bridge design, construction, and management paradigm to include structural modeling, instrumentation, and nondestructive testing. A baseline structural model is created and verified using structural health monitoring (SHM) data collected during a controlled static load test. The structural model is then used to calculate load rating factors of the bridge at both current and simulated damaged conditions. The resulting load rating factors are compared with the AASHTO load resistance factor rating method.

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

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, a...

Long-Term Thermal Performance of a CFRP-Reinforced Bridge Deck

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.

Baseline Model Updating During Bridge Construction Using Measured Strains

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.

Accounting for the Impact of Thermal Loads in Nondestructive Bridge Testing

This paper presents a research project currently funded by the Research Advisory Council of the New Hampshire Department of Transportation to develop a framework for bridge condition assessment integrating instrumentation and structural modeling for highway bridge decision-making and management. 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 model 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.