Design, Construction and Load Testing of the Pat Daly Road Bridge in Washington County, MO, with Internal Glass Fiber Reinforced Polymers Reinforcement

The overarching goal of this project is to deploy and assess an innovative corrosion-free bridge construction technology for long-term performance of new and existing bridges. The research objective of this project is to conduct a comprehensive study (instrumentation, construction, both laboratory and field evaluation) of a rapidly constructed and durable, three-span bridge with cast-in-place cladding steel reinforced concrete substructure and precast concrete decks/girders reinforced with glass fiber reinforced polymers (GFRP). The bridge has one conventional concrete-girder span, one conventional steel-girder span, and one innovative concrete box-girder span. The conventional concrete and steel girders were used to demonstrate the effective use of corrosion-free bridge decks in deck replacement projects and, as benchmarks, to demonstrate the pros and cons of the innovative concrete box girders. The bridge was instrumented with embedded strain gauges to monitor the strains at critical locations during load testing. The collected data will allow the understanding of load distribution in various GFRP bars of the innovative concrete box girders and bridge deck slabs. Specifically, a full-scale concrete box girder and a full-scale concrete slab with internal GFRP reinforcement were tested in the Highbay Structures Laboratory at Missouri S&T to ensure that the test bridge components behaved as designed prior to the field construction. Furthermore, in-situ load tests of the completed bridge were conducted to demonstrate the load capacity and behavior of individual components and the bridge as a system. The field validated technology will have a longlasting value for future deck replacement projects of existing bridges and new constructions. It will provide a viable alternative to conventional bridge systems/materials for the improvement of our Nation\u27s deteriorating infrastructure

Structural Behavior Evaluation of a Steel Frame in Simulated Post-Earthquake Fire Environment Using a Comprehensive Sensing Network

Earthquake induced disasters have occurred more frequently in recent years. During or after a seismic event, civil infrastructure not only experiences potential vibration-induced structural damage but also is subjected to earthquake-induced harsh environments, such as post-earthquake fire, explosions, and nuclear radiations. Material softening in a fire environment adds significant deformation to steel structures that may have already experienced inelastic deformation due to earthquake effects, leading to progressive collapses. On one hand, the behavior of critical structures needs to be monitored in real time in order to develop the best rescue strategy under harsh conditions. On the other hand, current technologies for structural health monitoring encounter application challenges in these environments in terms of survivability, measurement range, sensitivity, and cost. This paper investigated the structural behavior of a steel frame under simulated post-earthquake fire conditions by using a comprehensive sensor network, including a commercial temperature and strain sensor system and an optical fiber sensing system. The commercial system consists of high temperature strain gauges and thermocouples. The optical system is a quasi-distributed sensing system composed of long period fiber grating (LPFG), fiber Bragg grating (FBG), extrinsic Fabry-Perot interferometer (EFPI), and improved hybrid EFPI/LPFG sensors. Laboratory tests have demonstrated that the optical sensor system with movable EFPIs, LPFGs, and improved hybrid EFPI/LPFG sensors can measure strain up to 12% at 700 °C. By using the comprehensive sensing network, the structural behavior of the steel frame can be monitored and evaluated to provide insightful information on the development of the frame\u27s inelastic deformation under the postulated post-earthquake fire condition

Experimental Validation of Finite Element Model Analysis of a Steel Frame in Simulated Post-Earthquake Fire Environments

During or after an earthquake event, building system often experiences large strains due to shaking effects as observed during recent earthquakes, causing permanent inelastic deformation. In addition to the inelastic deformation induced by the earthquake effect, the post-earthquake fires associated with short fuse of electrical systems and leakage of gas devices can further strain the already damaged structures during the earthquakes, potentially leading to a progressive collapse of buildings. Under these harsh environments, measurements on the involved building by various sensors could only provide limited structural health information. Finite element model analysis, on the other hand, if validated by predesigned experiments, can provide detail structural behavior information of the entire structures. In this paper, a temperature dependent nonlinear 3-D finite element model (FEM) of a one-story steel frame is set up by ABAQUS based on the cited material property of steel from EN 1993-1.2 and AISC manuals. The FEM is validated by testing the modeled steel frame in simulated post-earthquake environments. Comparisons between the FEM analysis and the experimental results show that the FEM predicts the structural behavior of the steel frame in post-earthquake fire conditions reasonably. With experimental validations, the FEM analysis of critical structures could be continuously predicted for structures in these harsh environments for a better assistant to fire fighters in their rescue efforts and save fire victims

Large-Strain Optical Fiber Sensing and Real-Time FEM Updating of Steel Structures under the High Temperature Effect

Steel buildings are subjected to fire hazards during or immediately after a major earthquake. Under combined gravity and thermal loads, they have non-uniformly distributed stiffness and strength, and thus collapse progressively with large deformation. In this study, large-strain optical fiber sensors for high temperature applications and a temperature-dependent finite element model updating method are proposed for accurate prediction of structural behavior in real time. The optical fiber sensors can measure strains up to 10% at approximately 700 °C. Their measurements are in good agreement with those from strain gauges up to 0.5%. In comparison with the experimental results, the proposed model updating method can reduce the predicted strain errors from over 75% to below 20% at 800 °C. The minimum number of sensors in a fire zone that can properly characterize the vertical temperature distribution of heated air due to the gravity effect should be included in the proposed model updating scheme to achieve a predetermined simulation accuracy