Methee Chiewanichakorn

Failure analysis of fiber-reinforced polymer bridge deck system

Throughout the United States including New York, many reinforced concrete bridges on county and state highway systems have deteriorated to the certain degree that structural strengthening is necessary to extend their service life. Fiber reinforced polymer (FRP) composite systems appeared to be one of the options to address the issues of cost-effective load-rating improvement. Recently, an FRP deck has been installed on a state highway, located in New York State, as an experimental project. This paper describes multi-step linear static analyses that were conducted using the finite element method to study the possible failure mechanisms of the deck-superstructure system. Finite element model was verified using the load tests of the bridge deck. Furthermore, the thermal behavior of the FRP deck was investigated and presented in this paper. Analytical results reveal several potential failure mechanisms for the FRP deck and truss bridge system.

Cyclic Performance of Precast Concrete Segmental Bridge Columns: Simplified Analytical and Finite Element Studies

The cyclic performance of an unbonded precast concrete segmental bridge column system is examined in this paper. This system uses unbonded posttensioning to enhance the self-centering capability and mild steel reinforcement extended across the segment joints to enhance the energy dissipation capability. A simplified analytical method for the system under lateral load is established, and the simplified analytical results are compared with those obtained from the three-dimensional (3-D) finite element method (FEM). On the basis of the simplified analytical method, suggestions are made about both the height of the column to which the mild steel should be continued from the foundation and the limitation of the steel ratio to minimize residual displacement. With the steel ratio varied, the correlation between the energy dissipation capability and the self-centering capability of this system is investigated by means of the 3-D FEM. From simulation results, it was found that both the energy dissipation and the r...

Simulations of structural behaviour of fibre-reinforced polymer bridge deck under thermal effects

Finite Element Method (FEM) has been employed to study the structural behaviour of two different Fibre Reinforced Polymer (FRP) bridge deck systems under thermal effects. Bridge system I is a hybrid FRP-concrete bridge superstructure, while bridge system II is an all FRP bridge deck on steel girder. Because the Coefficient of Thermal Expansion (CTE) of the FRP is higher than that of concrete, this study investigated the behaviour of bridge system I under different climatic conditions. This study describes the behaviour of bridge system II subjected to thermal loading from a truck fire incident combined with mechanical loading from the commercial trucks. Furthermore, fully coupled thermal-stress analyses were performed using FEM to determine the fire resistance limit. The paper illustrated that the thermal response of bridge system I would be significant under severe climatic conditions. Moreover, the thermal simulations showed that bridge system II is highly sensitive to the effect of elevated temperatures.

Methodologies for Evaluation of Effective Slab Width

A composite section is made up of a steel girder and concrete slab connected by shear connectors. The shear lag phenomenon usually takes place in such a section and results in underestimation of stresses and strains at the web-to-flange intersections of the girder. With the introduction of the concept of effective slab width, the actual width can be replaced by an appropriate reduced slab width. The classical effective slab width definition does not take into account the strain variation through the slab thickness. More sophisticated definitions are introduced and used with finite element analyses. The method of finite element modeling is discussed, and the model is successfully verified with experimental results. Parametric study is conducted to investigate the effective slab width for both positive and negative moment sections. The effective slab width is computed and compared with the current AASHTO load and resistance factor design (LRFD) specifications. The results demonstrate that full width can be used as the effective slab width in the design and analysis in most cases for the design and analysis of both positive and negative moment sections. The current AASHTO LRFD specifications are found to be conservative for configurations with widely spaced girders, especially in negative moment sections.

Finite Element Simulations of Seismic Response of Precast Concrete Segmental Columns

For accelerated bridge construction, substructures are critical path elements of the schedule in many cases. In order to accelerate the construction of substructures, in particular, piers, precast concrete segmental columns (PCSC) has been used for a number of projects. However, their application in strong seismic regions is very limited because of lack of experience and knowledge. Recently, several analytical and experimental studies investigated the possibilities and the problems of PCSCs. It has been observed that the interface between segments experience opening-closing under cyclic loadings, which prevent the formation of plastic hinges at the intended bottom/top of the column. In this present study, a finite element analysis scheme is developed for analyses of PCSCs. The modeling requires accurate and robust characterization of concrete material, reinforcing steel, post-tensioning tendons, and segmental interfaces. Finite element analysis pushover results compared well with available experimental results. The finite element analysis scheme was extended to determine seismic characteristics of the system. Furthermore, seismic response of the structures subjected to earthquake ground motions is to be investigated based on nonlinear dynamic time-history analysis.

Experimental Study on Ultimate Behavior at Negative Moment Regions of Composite Bridges

This paper presents experimental results of the ultimate behavior of the negative moment region of a quarter-scale full model and a half-scale subassemblage model of a two-span continuous composite bridge of concrete deck slab on steel girder. The two specimens are based on a prototype bridge that has a large girder spacing [3,800 mm (13 ft)]. At the ultimate state, it is shown that a larger portion of the deck is activated to resist tensile stress compared with the effective width specified in the AASHTO load and resistance factor design bridge specifications. Also, a plastic hinge that forms at the internal support has enough rotational capacity (ductility) to enable development of a second plastic hinge within the span. Experimental results show a reasonably good match with accompanying finite element method analyses.

Part 1: General Structures: Experimental Study on Ultimate Behavior at Negative Moment Regions of Composite Bridges

This paper presents experimental results of the ultimate behavior of the negative moment region of a quarter-scale full model and a half-scale subassemblage model of a two-span continuous composite bridge of concrete deck slab on steel girder. The two specimens are based on a prototype bridge that has a large girder spacing [3,800 mm (13 ft)]. At the ultimate state, it is shown that a larger portion of the deck is activated to resist tensile stress compared with the effective width specified in the AASHTO load and resistance factor design bridge specifications. Also, a plastic hinge that forms at the internal support has enough rotational capacity (ductility) to enable development of a second plastic hinge within the span. Experimental results show a reasonably good match with accompanying finite element method analyses.