Numerical Study of Various Steel Plate Configurations for Rejoining an Asymmetrical Steel Section - Composite Concrete Beams

Comparative study on flexural behavior of steel-UHPC composite beams and steel-ordinary concrete composite beams in the negative moment zone

Experimental study and numerical simulation on shear behavior of steel and concrete composite beam with molybdenum tailing

Cold-formed U-shaped steel and concrete composite beam is a kind of composite beam which the steel and the concrete are integrated by welding connections on the cold-formed U-shaped steel and then pouring concrete on the steel. Now, many experts and scholars have carried out many experimental research and theoretical analysis about it. But, prestressed Cold-formed U-shaped steel and concrete composite beams have not been studied. Based on the structure , the nonlinear analysis mode of prestressed cold-formed U-shaped steel and concrete composite beams is proposed, the calculating program is researched. The calculating results show that the bearing capacity of composite beam increases with the increments of thickness of steel plate and concrete strength, and the thickness of steel plate has a larger effect than the width of the flange plate of concrete, applying prestress can enhance the bearing capacity and flexural rigidity of the composite beam.

Continuous double steel and concrete composite beam is a new structural system developed on the basis of common steel and concrete composite beam. Controlling concrete slab crack width in a continuous double composite beam is a significant content in the bridge construction process. Jacking-up and landing bearing supports method is applied to a double composite girder bridge construction and its structural mechanical behaviors in the whole process will be simulated. By using of User Programmable Features and ANSYS Parametric Design Language, the commercial FEM software ANSYS was further developed. The exponential model of concrete creep and the implicit solution of concrete creep equation under the action of variable stress were introduced into ANSYS, to realize the concrete shrinkage and creep effect analysis of double composite continuous box-girder bridges constructed by pre-jacking method. The results show that it is improved that the stress state of the top concrete slab in the negative moment regions by pre-jacking method. Due to the effect of concrete creep, the concrete creep will cause tensile stress in the negative moment regions of the composite beam, which will reduce the compressive stress in the top concrete slab. The effect of prestressing is greatly affected by pre-jacking value, and the creep of the concrete also causes the stress redistribution of the concrete and the steel beam.

Nonlinear behaviour of unprotected composite slim floor steel beams exposed to different fire conditions

This paper examines the experimental flexural performance of the strengthening composite concrete asymmetrical castellated steel beam of double channel shape by connecting two castellated hot rolled steel channels back-to-back using bolts along its length to obtain a built-up I-shaped form with a new total beam depth heightened by 52.4%. This research tested four specimens: the first was a reference specimen without any strengthening techniques; the second was strengthened with RPC (Reactive Powder Concrete) in the steel web region; the third was strengthened by RPC reinforced with a lacing rebar. Also, this study investigated the welding effects in web posts for the top and bottom parts of the castellated steel in the fourth specimen. All specimens were tested under simply supported conditions by applying two-point static loads on the concrete deck slab of the composite beams. The ultimate load deflection, stiffness, ductility, energy absorption capacity, and failure mode were investigated and discussed. According to the experimental results, the ultimate load capacity increased 24.01% and 48.34% in the second and third specimens, respectively, with increased stiffness, ductility, and energy absorption capacity compared with the first specimen. In contrast, the ultimate load capacity decreased by 11.02 % in the fourth specimen (strengthening without welding in web posts), reducing stiffness and ductility compared with the first specimen (reference).

The effects of creep and shrinkage of concrete is non-ignorable to strength of steel and concrete composite beams under sustained load, and the relative slippage should be considered for internal force. Time-dependent modulus method is presented, formulas of the stress and strain at any time are deduced considering creep, shrinkage and the relative slippage. The variational stress is analysed of the steel and concrete composite beams under sustained load.

The effects of creep and shrinkage of concrete is non-ignorable to strength of steel and concrete composite beams under sustained load, and the relative slippage should be considered for internal force. Time-dependent modulus method is presented, formulas of the stress and strain at any time are deduced considering creep, shrinkage and the relative slippage. The variational stress is analysed of the steel and concrete composite beams under sustained load.

Experimental investigation on flexural strength behaviour of reactive powder concrete

This paper presents experimental and theoretical research for calculating of composite steel and concrete beams deflection strengthened bonded steel plates. The use of epoxy-bonded plates to strengthen existing or damaged reinforced or composite steel beams concrete beams has been extensively researched. It has been proven to be a useful and reliable method of increasing the ultimate flexural capacity of both damaged and undamaged members. The actual deflection behavior in beams is probabilistic in nature and requires statistical methods for a rational analysis.

This study examines experimentally the mechanical performance of composite steel and concrete beams with expansion joints in the concrete slab. Four composite beams with expansion joints in the concrete slab were tested, and various aspects of such beams including the effects of expansion joint locations ([Formula: see text], [Formula: see text], and [Formula: see text], where [Formula: see text]), expansion joint sizes (through and half-through of the concrete depth), and loading conditions (positive bending moment and negative bending) etc., were investigated. Load versus vertical deflection responses at key sections, and the strain development and distribution on the steel beam were measured. To explore the behavior of shear connectors on or near the expansion joint sections, the normal strain on shear connectors was measured. The bending strain and axial strain of shear connectors on joint sections were also discussed in detail. The theoretical methods for predicting the rigidities and ultimate load-carrying capacities of the composite beams were examined, and it was found that the current AASHTO-LRFD criterion without considering expansion joints in a concrete slab can still provide conservative estimations of ultimate loads of such beams under a negative moment. For composite beams under a positive bending moment, however, they are not applicable, due to the different failure modes. The test results from this research provide new information for improving the design, construction, management, maintenance, and structural health assessment of such beams that can be used in bridges and buildings, etc.

The fatigue behaviour of composite steel and concrete beams with stud shear connectors is unusual because the mechanical properties of the connectors are continually changing under the application of cyclic loads. Tests have conclusively shown that stud shear connections reduce in strength and stiffness immediately after cyclic loads are applied; however, friction at the interface between the concrete slab and the steel beam reduces the forces on the stud shear connectors. These effects can both enhance or reduce the endurance, stiffness and strength of the composite beam, which makes the fatigue design and assessment a very interesting and unique problem. This review describes the changes in properties that occur due to cyclic loading and the mathematical models that have been developed both to simulate the fatigue behaviour of composite beams and to estimate their remaining strength and endurance.

In the design of new composite steel and concrete bridge beams, the shear connectors are assumed to transmit all of the longitudinal shear forces at the interface between the concrete slab and the steel beam. However, in practice, the forces on the shear connectors are modified by friction resistances at the interface. The effect of friction on the fatigue endurance of shear connectors is first illustrated through a specially developed finite-element analysis procedure. Then a simple mathematical assessment model is proposed that allows for the beneficial effect of friction on the fatigue endurance of shear connectors in composite steel and concrete bridge beams. This procedure can extend the design life of the shear connectors in existing composite bridge beams, as it can be used to estimate their remaining endurance and their remaining strength and, if necessary, to determine the effect of remedial work on increasing the endurance of the shear connectors.

The composite steel and concrete structures are used for constructing bridge floors and others buildings. The joint action of composite structures as well as their economic efficiency depends on the connection between the layers, i.e. stiffness of the steel beam and the concrete slab. Under the effect of external load in the connection of steel and concrete the shear deformations occur. The size of these deformations depends on the effective shear stiffness of the connection of layers. When designing the composite steel and concrete structures it is very important to accurately calculate their deflections. Deflection is largely dependent on the stiffness of the connection of steel and concrete. In isolated cases it is purposive to calculate the necessary stiffness of the connection of steel and concrete taking into consideration the permissible deflection of the composite steel and concrete structure. This paper gives the methodology which, based on the known permissible deflection of the structure, allows to calculate the necessary equivalent effective shear modulus of the steel-concrete connection. Experimental investigations of the composite steel and concrete beams were carried out. Deflections of the composite beams, also the shear deformations of steel and concrete connections and the effective shear stiffness of this connection were determined. Theoretical calculations of the effective shear stiffness of the connection of concrete slab and steel beam of the experimental composite steel and concrete beams were conducted. Investigations showed a rather good correspondence between the experimental and theoretical investigation results.

Partial interaction in composite steel and concrete beams with full shear connection