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Movement of industrial freight infrequently requires special overload vehicles weighing 5 to 6 times the normal legal truck weights. The gross vehicle weight of the vehicles frequently exceeds 1800 kN whereas, the normal interstate legal limit in the United States is 356 kN. Because of the unusual configuration of the vehicles, it is difficult to analyze the effect of these loads on highway bridges by using current simplified analysis methods. This report aims to provide modified moment and shear load distribution factor equations for the vehicles to quickly determine their effects on multigirder bridges. Finite element analyses of 118 multigirder bridges and 16 load cases of overload vehicles for each multigirder bridge were performed, and the load distribution factor equations for the multigirder bridges were proposed on the basis of the analysis results. Various configurations of the vehicles, number of bridge spans, skew angles of the bridge and diaphragms were considered in developing the equ...

Studies on two novel uses of hybrid structural members consisting of commercially produced glass reinforced pultruded ribbed fiber reinforced polymer (FRP) planks and concrete are discussed in this paper. Pultruded planks are produced by all the major pultruders in the world and are utilized primarily as decking for platforms. These highly optimized panels have the potential to be used in many other infrastructure applications, but their flexural stiffnesses have generally been too low to be used in highway and pedestrian bridges due to current span requirements. However, when used “compositely” with concrete or cementitious materials in a hybrid form they have the potential to be much more widely used. Two research studies conducted on two possible hybrid systems of different structural depths are discussed in this paper. The first study describes the use of pultruded planks as permanent formwork in highway bridge decks where the plank is used with concrete to produce a solid slab of 200 mm depth that is typical of slabs seen in highway bridge decks. The second study describes the use of pultruded planks in pedestrian bridge decks where the pultruded plank is used with a cement-board or a cast-in-place concrete panel to produce a hollow slab of 75 mm depth that is typical of timber decking used in FRP pedestrian bridges. Tests were conducted on beam-type specimens of the hybrid slabs to investigate the load transfer mechanisms between the pultruded plank and the cementitious “overlays” for both the 75 mm and 200 mm depths. From analysis of the load-carrying capacity and failure mechanisms of the hybrid slabs it was concluded that such hybrid slabs are viable systems for both highway and pedestrian bridge decks. A bridge deck using the 200 mm deep hybrid slab system was recently constructed on a highway in Wisconsin, USA.

A feasibility study in which the use of a commercially produced pultruded fiber reinforced polymer (FRP) plank for both permanent formwork and secondary or primary tensile reinforcement of a concrete structural member is described in this paper. To achieve satisfactory bond at the interface between the smooth surface of the FRP plank and the concrete, two kinds of aggregate, gravel and sand, were epoxy bonded to the planks. Concrete beams using the aggregate-coated FRP planks were fabricated and tested. Satisfactory bond between the FRP plank and the concrete was developed which was evidenced by numerous well-distributed flexural cracks, and ultimate capacities of the aggregate coated FRP plank specimens greater than the steel rebar reinforced control specimen. ACI 440 equations were found to provide good predictions of the flexural strengths but poor predictions of the shear strengths of the FRP plank reinforced beams. ACI 318 equations, however, provided good shear strength predictions.

We perform an experimental study of concrete beam with pultruded fiber reinforced polymer(FRP) plank using as a permanent formwork and the tensile reinforcement. A satisfactory bond at the interface between the smooth surface of the pultruded plank and the concrete must be developed for the FRP plank and the concrete to act as a composite structural member. Two kinds of aggregate were bonded to the FRP plank using a commercially available epoxy. No additional flexural or shear reinforcement was provided in the beams. For comparison we test two types of control specimen. One control did not have any aggregate bonded to the FRP plank and the other control had infernal steel reinforcing bars instead of the FRP plank. The beams were loaded by central patch load to their ultimate capacity. The experimental results were compared to current ACI 318 (2005) and ACI 440 (2006) code predictions. This study demonstrates that the FRP plank has the potential to serve as formwork and reinforcing for concrete structures.

This study presents a new method for predicting the strength of reinforcement-free bridge decks. The concept presented for the reinforcement-free bridge deck includes removing steel reinforcement, using compressive membrane action in the deck by tying concrete wide-flanged girders together, and introducing a polypropylene fiber to control shrinkage cracks. A modified strut-and-tie model (STM) that considers geometrical nonlinearity that can capture punching or flexural failure of the restrained bridge deck between the girders is proposed. The model provides a two-dimensional axisymmetric representation of the behavior of the reinforcement-free deck. Results from the proposed STM analysis method are compared to nonlinear finite element method (FEM) analysis results. Findings suggest that the proposed method is a practical and effective replacement for the time-consuming FEM analysis when the clear deck spans are 5ft or less.