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Project Title: Structural behaviour of beam to concrete-filled elliptical steel column connections

  • PhD Student: Naveed Rehman
  • Supervisors: Professor Dennis Lam, Dr Xianghe Dai and Dr Ashraf Ashour

Background

During last few decades, much emphasis has been placed on environmental matters such as sustainability, energy, waste and deconstruction by reusing used materials. So the Government is trying to focus on sustainability and low carbon emissions to the environment and the effective reuse of materials. Buildings have a great impact on the environment, especially the demolition of structures.

Composite beams with metal decking are very common in today’s building industry because they are economical and allow for speedy construction. In composite beams, welded shear connectors are used to achieve the composite action of the slab and beam. It becomes very difficult to dismantle the composite structures with welded headed shear connectors and their components cannot be reused without the input of significant energy for their structural modification.

It is therefore considered whether demountable headed shear connectors are a viable idea as an alternative shear connector. The design of demountable shear studs has emerged to facilitate future reuse of steel beams without going to the recycling process, as the steel beams are often recycled to reuse them again. The steel beams do not degrade with use unless they have undergone major damage. The replacement of welded headed stud shear connectors with demountable headed shear studs offers big advantages such as the ease with which the composite beam and slab can be dismantled.

Aims

The primary goal of this research is to investigate the behaviour of demountable shear studs in a composite beam and in push-out tests. More specifically, the objectives of this research are:

  • To check the strength, ductility and stiffness of demountable studs through push-out tests using the parameters of concrete strength, stud height and diameter, stud layout and positions of reinforcement to develop a modified push-out test.
  • To carry out a beam test for the measurement of end slip, mid-span deflection and strains in concrete slab and to identify the mode of failure.
  • To create a numerical model for a parametric study and for validating the laboratory experiment.

Setting up the 'Push-out test rig'. Methodology

Push-out tests are used to test the ductility, stiffness and shear capacity of a demountable stud in a composite slab with a beam. EN1994-1-1:2004 describes the standard ‘Push out test’ details. But in this research project the push-out details are modified to carry out the test in the laboratory. Two small concrete slabs with metal decking were connected with steel sections through demountable studs and placed vertically under the hydraulic actuator. LVDTs were used to measure the displacement and load was applied through the hydraulic actuator on the beam vertically downward. Further beam and push-out tests with demountable studs will be carried out in the near future.

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