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No / This paper presents a numerical investigation into the behaviour of headed shear stud in composite beams with profiled metal decking. A three-dimensional finite element model was developed using general purpose finite element program ABAQUS to study the behaviour of through-deck welded shear stud in the composite slabs with trapezoidal deck ribs oriented perpendicular to the beam. Both static and dynamic procedures were investigated using Drucker Prager model and Concrete Damaged Plasticity model respectively. In the dynamic procedure using ABAQUS/Explicit, the push test specimens were loaded slowly to eliminate significant inertia effects to obtain a static solution. The capacity of shear connector, load-slip behaviour and failure modes were predicted and validated against experimental results. The delamination of the profiled decking from concrete slab was captured in the numerical analysis which was observed in the experiments. ABAQUS/Explicit was found to be particularly suitable for modelling post-failure behaviour and the contact interaction between profiled decking and concrete slabs. It is concluded that this model represents the true behaviour of the headed shear stud in composite beams with profiled decking in terms of the shear connection capacity, load-slip behaviour and failure modes.

The behavior and strength of welded shear studs are subjects of ongoing study. In recent years, research has shown that the American Institute of Steel Construction (AISC) specification equations for shear stud strength are unconservative for studs placed in deck with ribs transverse to the steel beam. Twenty-four solid slab push-out tests, 93 composite slab push-out tests, and bare stud tests were performed to study the effects on stud strength of friction, normal load, position of studs in the ribs of steel deck, concrete strength, and stud properties. Stud diameters ranged from 3/8 in. to 7/8 in., deck heights ranged from 2 in. to 6 in., and both single and pairs of studs were tested. The push-out test results from this study were combined with other studies to propose a new stud strength prediction model. Three new beam tests were performed to study the effect of the stud position in the ribs of the steel deck. The results of these tests, along with 61 other beam tests, were used to verify the new stud strength prediction model. A reliability study was performed to determine resistance factors for stud strength and beam strength. / Ph. D.

As the aging bridges and infrastructure within the US continue to deteriorate, traffic delays due to construction will become more and more common. One method that can reduce delays due to bridge construction is to use precast deck panels. Precast deck panels can significantly reduce the overall length of the construction project. The panels can be manufactured ahead of time, and with higher quality control than is possible in the field. One of the reasons precast deck panels are not widely accepted is because of a lack of research concerning the required post-tensioning force, shear stud pocket placement, and proper joint design. In a recent dissertation (Swenty 2009) numerous recommendations were made for joint design, shear stud pocket design, and post-tensioning force for full-depth precast deck panel bridges. Design drawings were included for the replacement of a bridge located in Scott County, Virginia. The research in this report focuses on the short-term and long-term testing of this bridge. The short-term testing involved performing a live load test in which two trucks of known weight and dimensions were positioned on the bridge in order to maximize the negative moment at the joints over the piers and document strains and deflections at a number of other critical locations. The long-term testing involved monitoring the strains within the deck and on one of the six girders for a number of months in order to document the changes in strain due to creep and shrinkage. The results of these tests were compared to 2D beam-line models and to the parametric study results of Bowers' research on prestress loss within full-depth precast deck panel bridges. It was determined that the bridge was acting compositely and that the post-tensioning force was sufficient in keeping the joints in compression during testing. / Master of Science

Flat slab-column connections are common elements in reinforced concrete (RC) structures such as parking garages. In cold weather regions, these structures are exposed to de-icing salts and aggressive environments. Using fiber reinforced polymer (FRP) bars instead of steel in such structures will overcome the corrosion problems associated with steel reinforcement. However, the available literature shows few studies to evaluate the behaviour of FRP-RC interior slab-column connections tested mainly under concentric loads, which seldom occurs in a real building. The main objectives of this research are to deal with this gap by investigating the behaviour of full-scale glass (G) FRP-RC interior slab-column connections subjected to eccentric load and to provide design recommendations for such type of connections. This study consisted of two phases, experimental and analytical. The experimental phase included the construction and testing of ten full-scale interior slab-column connections. The parameters investigated in the experimental phase were flexural reinforcement ratio, concrete compressive strength, type of the reinforcement, moment-to-shear ratio and the spacing between the shear stud reinforcement. Test results revealed that increasing the GFRP reinforcement ratio or the concrete strength increased the connection capacity. Moreover, compared to the control steel-RC specimen, the GFRP-RC connection with similar reinforcement rigidity showed comparable capacity and deflection at failure. Also, increasing the moment-to-shear ratio resulted in a reduction in the vertical load capacity, while using the shear stud reinforcement enhanced the strength up to 23%. In the analytical phase, a 3-D finite element model (FEM) was constructed using specialized software. The constructed FEM was able to predict the experimental results within a reasonable accuracy. The verified FEM was then used to conduct a parametric study to evaluate the effects of perimeter-to-depth ratio, column aspect ratio, slab thickness and a wide range of flexural reinforcement ratio. The numerical results showed that increasing the reinforcement ratio increased the connection capacity. In addition, increasing the perimeter-to-depth ratio and slab thickness reduced the punching shear stresses at failure, while, the effect of the column rectangularity diminished for a ratio greater than three. Moreover, the results showed prominent agreement with the experimental results from literature. / October 2015

The use of fibre reinforced polymer (FRP) composites as an alternate to steel has proved to be an effective solution to the corrosion problem. However, FRP bars have low axial and transverse stiffness compared to steel bars which results in a lower shear capacity of FRP reinforced concrete (RC) elements compared to steel-RC elements. Flat plate systems are commonly used to take advantages of the absence of beams. They, however, are susceptible to punching shear failure where the column suddenly punches through the slab. An experimental program was conducted to investigate the punching shear behaviour of slab-column edge connections. Nine isolated full-scale slab-column edge connections were constructed and tested to failure. One connection was reinforced with steel flexural reinforcement, six with GFRP flexural reinforcement and two with GFRP flexural and shear reinforcement. The parameters investigated were the flexural reinforcement type and ratio, the moment-to-shear ratio and the shear reinforcement spacing.

The continuous permanent metal deck form system provides a quick and efficient method of constructing short-span, simply supported composite steel girder bridges. However, because shear studs can only be welded to the girder through the steel deck at rib locations, the number of shear stud locations is limited to the number of ribs in the shear span while the spacing of the shear studs is restricted to the rib spacing of the steel deck. This results in a condition where various provisions of the AASHTO LRFD Bridge Design Specifications (2007) cannot be satisfied, including shear stud fatigue spacing requirements and the fully composite section requirements. The purpose of this research was to investigate whether continuous permanent metal deck form construction method can be used for bridges given the code departures. Using this method, a full scale test specimen was constructed with one half of the specimen using one stud per rib and the other half using two studs per rib and then each half was tested separately. The steel deck used in the specimen was supplied by Wheeling Corrugating. Fatigue testing was conducted to determine the fatigue resistance of the specimen at both levels of interaction, with load ranges calculated using the AASHTO LRFD shear stud fatigue equation. This was followed by static tests to failure to determine the plastic moment capacity at both levels of interaction. Results of the testing were compared to existing design models and modifications specific to this construction method are made. Investigations into whether the profiled steel deck can act as full lateral bracing to the steel girder compression flange during deck placement were also made. Fatigue testing results showed that very little stiffness was lost over the course of testing at both levels of composite interaction. This leads to the conclusion that the AASHTO shear stud equation used for this design is conservative. Static testing results indicated that the measured values for the plastic moment capacity of the specimen were less than the calculated capacity. This leads to the conclusion that the individual shear stud strengths were overestimated using current design equations. Recommendations for modifications to the existing design equations are provided. / Master of Science

This study consists of three self-standing parts, each dealing with a different aspect of design of composite steel-concrete flexural members. The first part deals with a new type of shear connection in composite joists. Composite steel-concrete flexural members have increasingly become popular in design and construction of floor systems, structural frames, and bridges. A particularly popular system features composite trusses (joists) that can span large lengths and provide empty web space for installation of typical utility conduits. One of the prominent problems with respect to composite joists has been the installation of welded shear connection due to demanding welding requirements and the need for significant welding equipment at the job site. This part of the study presents a new type of shear connection developed at Virginia Tech— standoff screws. Results of experimental and analytical research are presented, as well as the development of a recommended design methodology. The second part deals with reliability of composite beams. Constant research advances in the field of composite steel-concrete beam design have resulted in numerous enhancements and changes to the American design practice, embodied in the composite construction provisions of the AISC Specification (AISC 1999). Results of a comprehensive reliability study of composite beams are presented. The study considers specification changes since the original reliability study by Galambos et al. (1976), considers a larger database of experimental data, and analyses recent proposals for changes in design of shear connection. Comparison of three different design methods is presented based on a study of 15,064 composite beam cases. A method to consider effect of degree of shear connection on strength reduction factor is proposed. Finally, while basic analysis theories between the two are similar, requirements for determining the strength of composite beams in Eurocode 4 (CEN 1992) and 1999 AISC Specification (AISC 1999) differ in many respects. This is particularly true when considering the design of shear connections. This part of the dissertation explores those differences through a comparative step-by-step discussion of major design aspects, and accompanying numerical example. Several shortcomings of 1999 AISC Specification are identified and adjustments proposed. / Ph. D.

The shear capacity of headed studs in precast concrete hollow-core slab construction has been determined experimentally in 12 full-scale push-off tests. The tests were used to study the effects of the size of the gap between the ends of the precast slabs, and the amount of tie steel placed transversely across the joint, and the strength of concrete infill. Under certain situations the capacity of the stud is reduced compared with that in a solid reinforced concrete slab. Maximum resistances are compared with the predictions of BS 5950 and EC4, and a reduction formula for the precast effect is derived.