Shear Strength Of Connections Research Articles

Deflection of Steel-Concrete Composite Beams with Partial Shear Interaction

This paper is concerned with calculating the maximum deflection of steel-concrete composite beams with partial shear interaction. Under the guidance of various current design codes, this deflection is related to the strength of shear connectors in the composite beam. In this paper, a shear connector stiffness based approach is developed. This approach is obtained based on the solution for a simply supported beam under uniformly distributed load. To validate this approach, the predicted maximum beam deflection using the proposed method is compared against the results from a linear-elastic finite-element analysis and some tests on composite beams. In both the finite-element analysis and the proposed method, uniform distribution of shear connection stiffness along the beam length is assumed. In the absence of a reliable way to calculate the shear connector stiffness, this paper suggests a simple procedure to obtain this value so that the proposed method may be used in practice.

An assessment of the effect of brace overstrength on the seismic response of a single-storey steel building

The effect of brace overstrength on the seismic response of a single-storey steel building with concentrically braced frames (CBFs) and a roof diaphragm that acts structurally is assessed by comparing the dynamic response of the building without overstrength to that of one with significant overstrength. Four structural idealizations are used that differ in modelling of the roof diaphragm and the CBFs. Dynamic response is obtained by time history analyses of the models with an appropriate set of 20 historical earthquake accelerograms scaled to zone 4. An oversupply of strength and stiffness increases the seismic demand on the building. The response is significantly influenced by the model used. Columns and brace connections of the CBF are overloaded if the diaphragm is considered to be rigid and its limited shear connection strength ignored. When this connection strength is considered, the ductility demand is localized at the connection and consequently the CBF is not overloaded. Similar results are obtained with a model that accounts for the distributed mass and flexibility of the diaphragm and its shear connection strength. The study emphasizes that designers should consider the strength and stiffness of all elements in the lateral load path. Implications for seismic design and rehabilitation analyses are discussed.

The effect of precast concrete planks on shear connector strength

The use of precast concrete planks as permanent shutters reduces the effective in situ concrete around the shear connectors in composite beams. Results are presented which show that a minimum 100 mm width of in situ concrete allows 19 mm diameter, 115 mm long studs to develop their full shear capacity provided recommended reinforcement details are used.

Partial shear connection design of composite slabs

A new partial shear connection strength model has been developed which considers the equilibrium of a segment of a simply-supported composite slab under any loading condition. The model incorporates shear connection performance derived from a new test called the slip block test. This small-scale test shows that shear connection performance is affected by factors such as profile geometry, base metal thickness and concrete compressive strength. Full-scale slab tests have proved that it is a reliable physical model which can readily account for the effects of changes in shear connection performance, loading pattern, sheeting end support conditions, end anchorage devices, conventional reinforcement etc., and is being developed for possible use in an Australian Standard on the design of composite slabs. The ease with which the model can be used in design is demonstrated in a worked example. Another new ultimate strength method of design, published by the Steel Deck Institute in America, is examined in the worked example, and shown to give erratic, sometimes overly conservative but often very unsafe predictions for the particular profiled sheet and design situations studied.

Shear Connectors in Composite Beams with Longitudinally Cracked Slabs

The longitudinal shear flow in composite steel and concrete beams is transferred across the steel‐flange‐concrete‐slab interface at a discrete number of points by the dowel action of individual shear connectors. The strengths of these dowels are affected by the presence of longitudinal cracks in the concrete slab that may have been formed by transverse flexural forces in the slab or by splitting or by shear forces that are induced by the dispersal of the dowel forces into the concrete slab. Twenty‐five push specimens are tested to determine the effect of transverse reinforcement on the dowel strength of shear connectors that are embedded in longitudinally cracked concrete slabs. This postcracking dowel strength is quantified, and it is found that it is affected by the stiffness of the transverse reinforcement, but not by its strength.

Partial-interaction analysis of composite beams with profiled sheeting and non-welded shear connectors

Following a brief review of the basis of the formula which determines the strength of shear connectors for composite beams, shear-connector strength is examined when profiled sheeting is used. New non-welded connectors have been tested using composite beams and push-out specimens, with and without profiled sheeting. The expression which determines strength reduction due to the presence of sheeting is valid for these new connectors provided that they are placed correctly, thereby ensuring ductility. The second part of the paper considers partial-interaction analysis of simply supported composite beams. The model proposed by Eurocode 4 is compared with an analysis of an equivalent section providing full interaction, with a more precise numerical analysis and with test results of composite beams employing non-welded connectors. It is concluded that if the connectors are sufficiently ductile, the minimum allowable degree of partial shear connection can be lowered to 25% from 50% (of full connection) without risk of connector failure for beams where connection is required to reduce deflections.

Headed shear stud connectors in a stub-girder floor system: a preliminary study

The performance of headed shear stud connectors which attach the reinforced concrete slab to the supporting structural steel stubs in a stub-girder structural floor system was examined by testing 28 portions or subassemblages of a complete stub-girder. The major difference which affected the performance of the shear connectors in a stub-girder floor system as compared with conventional composite construction was the increasèd tension which must be carried by critically located shear connectors. One cause of the increase in tension was the secondary bending which resulted from the transverse (beam) shear acting on the concrete slab along the open panel of the stub-girder between interior structural steel stubs. This behavior is similar to the bending which takes place in the chords of a Vierendeel truss.A significant reduction in the shear strength of the connectors resulted from the induced tension. However, the shear strength could be predicted using current Canadian code strengths if allowance was made for the tension in the connectors. The analysis suggested that the resultant of the full applied shear force and 75% of the applied tension force was comparable with the shear connector strength given in the code.