Kim S. Elliott

Parametric study on composite steel beams with precast concrete hollow core floor slabs

Abstract This paper describes the finite element modelling of steel beams acting compositely with proprietary precast hollow core slabs. A companion paper (Lam D, Elliott KS, Nethercot DA. Experiments on composite steel beams with precast hollow core floor slabs. Proceedings of the Institution of Civil Engineers: Structures and Buildings 1999; in press [1] ) reports results of full scale bending tests and compression slab tests. The finite element package ABAQUS was used to extend the scope of the experimental work, by first demonstrating that a 2-dimensional plane stress analysis is sufficiently accurate, providing that the correct material input data and shear stud characteristics obtained from isolated push-off tests are used. The FE results are within 5% of the experimental results. An extensive parametric study was carried out to investigate the flexural behaviour of composite beams with variations in transverse reinforcement ratio, stud spacing and steel UB section.

Experimental Determination of Strain Concentration Factors in RHS Truss Gap K-Connections

Two large-scale rectangular hollow section Warren trusses with welded gap K-connections have been tested elastically under single panel point loading and extensive strain measurements have been made around three connections with different size welds. From this strain data, Strain Concentration Factors have been determined according to accepted methods and compared with values predicted by current parametric formulae recommended by researchers at Delft University of Technology and University of Karlsruhe. Agreement with both procedures is good for the hot-spot on the bracing member, provided the fillet weld size is large relative to the member thickness, which is likely to be the case in most practical applications. For the hot-spot on the chord member, however, both of the above procedures significantly overestimate the Strain Concentration Factor, for large fillet welds. The influence of fillet weld size, connection noding eccentricity and location of a connection within a truss are all shown to be important influencing parameters and are discussed in the paper.

Modernisation, Mechanisation and Industrialisation of Concrete Structures

Kim S. Elliott is a consultant to the precast industry in the UK and Malaysia. He was Senior Lecturer in the School of Civil Engineering at Nottingham University from 1987-2010, and was formerly at Trent Concrete Structures Ltd., one of the UKs leading precast concrete manufacturers. An active researcher into the behaviour of precast concrete structures, he has published extensively on the subject. He is a member of FIB Commission on Prefabrication.

Steel — Concrete Composite Construction with Precast Concrete Hollow Core Floor

Publisher Summary Precast concrete hollow core floor units (hcu) are widely used in all types of multistorey steel framed buildings where they bear onto the top flanges of universal beams. The steel beam is normally designed in bending, in isolation from the concrete slab, and no account is taken of the composite beam action available with the precast units. A program of combined experimental and numerical studies was undertaken that aimed at deciding on a suitable approach for the design of composite steel beams that utilize precast concrete hollow core slabs. The results show that the precast slabs may be used compositely with the steel beams in order to increase both flexural strength and stiffness at virtually no extra cost, except for the headed shear studs. For typical geometry and serial sizes, the composite beams were found to be twice as strong and three times as stiff as the equivalent isolated steel beam. The failure mode was ductile, and may have been controlled by the correct use of small quantities of tie steel and insitu infill concrete placed between the precast units.

The Measurement of Plastic-Elastic Strains at Weld Toes Using Moiré Interferometry

Using moire interferometry, elastic, plastic-elastic and residual plastic strains have been measured at, and near to weld toes in real steel weldments. The shapes and loadings of the models are as in tubular joints used in offshore structures. Plastic-elastic strain concentration factors of up to 17 were measured at weld toes in a joint where the elastic value was 4. Strain gradients upto lOOOOµɛ/mm were measured near to the edges of Luders bands. Plastic strain reversals and strains in Luders bands were measured. Contours of plasticity at different load magnitudes are given. Moire interferometry is an excellent tool for studying inhomogeneous materials.