Concrete Composite Construction Research Articles

The effects of axial tension on the hogging-moment regions of composite beams

Structural parts commonly comprised of composite members such as bridge approaches, inclined parking ramps and stadium beams, can be subjected to a combination of high axial loads and bending moments. Steel–concrete composite construction is a popular solution for these types of structures due to the numerous advantages that they offer. Although, current design codes (e.g. Eurocode 4, American code AISC, Australian codes AS2327 and AS5100) provide rules for the design of composite columns subjected to flexure and axial load, however the design of composite beams, which are asymmetric in nature under the combined effects of tension and bending, is not yet fully addressed. This paper investigates the ultimate strength of composite beams under the combined effects of axial tension and negative (hogging) bending moment. An experimental programme carried out in the laboratory of the University of Western Sydney comprised of a total of six specimens representing composite beams and subjected to various levels of axial tension and bending moment. Ultimate failure modes were identified and the resulting interaction diagrams were compared to the results of sectional rigid plastic analysis. Following the tests, three-dimensional finite element models were employed using the ABAQUS finite element software to further investigate the nonlinear behaviour of the composite beams and extend the experimental observations by studying the effects of parameters such as the span length and the effect of partial shear connection. Finally, simple design rules and formulae are proposed for use in engineering practice.

Testing of self-consolidating concrete-filled double skin tubular stub columns exposed to fire

A concrete-filled double skin tube (CFDST) is an innovative steel and concrete composite construction with the potential to be used as columns in high-rise buildings. Self-consolidating concrete (SCC) can offer convenience for construction and ensure the construction quality of CFDST columns. There is very limited knowledge about the fire performance of CFDST columns, which is a key issue in the application to high-rise buildings. This paper reports an experimental investigation into the fire behaviour of CFDST stub columns filled with SCC and fibre reinforced SCC. The study aims to obtain thermal and structural responses of the stub columns through standard fire testing. Details are given in terms of the failure mode, temperature distribution, critical or limiting temperature and fire resistance. It was found that the added fibre does not affect the temperature distribution whereas the increased concrete thickness and outer tube perimeter reduces the temperature in CFDST specimens. The added steel fibre increases the fire resistance of CFDST stub columns especially for load levels less than 0.6. The critical or limiting temperature for CFDST sections was found to be higher than for CFST (concrete-filled steel tube) or unfilled tubes.

An Eye-Catching Car Park for the New Fairground in Stuttgart, Germany

A complete new fairground was built in Stuttgart just on the doorstep of the International Airport. Part of the fairground is a multi-storey car park. This car park is a steel and steel concrete composite construction with a total length of 440 m, a width of 100 m and a height of up to 22 m. It is positioned like a bridge over a very busy highway and a new railroad track for Germany's high speed train ICE. Due to the remarkable position it became the eye-catching landmark for the new fairground in Stuttgart.Due to the fact that the highway traffic should not be affected by the erection, the main parts of the construction were launched over the highway, while the traffic was still in full progress. More than 5,500 tons of steel and concrete structure where moved about 170 meters. With a speed of 6 m per hours, six separate moves were necessary to place the structure into the final position.The car park was opened to the public on June 12th 2007 and contains space for more than 4,000 cars. In September 2007 the construction company received the European award for steel structures 2007 for this extraordinary building. This paper describes the structure of the car park, the concept of the fire protection, an interesting detail and the erection of the structure.

Technical Note: Double composite steel–concrete bridges

This technical note outlines the concept of double composite action. It summarises the potential advantages of a double composite steel–concrete structure over the more common steel–concrete composite construction, particularly for continuous structures. A comparative study of three bridge forms with and without double composite action is outlined and the reduction in steel tonnage for the double composite type of each form is estimated.

Vibration characteristics of steel–concrete composite floor systems

AbstractTrends towards long‐span, lightweight floors in steel–concrete composite construction are resulting in structures possessing low natural frequencies, and potentially susceptible to vibration problems. The most common source of vibrations is caused by human activities on the floor, however, in some instances, mechanically induced vibrations from air conditioning plant, etc. may also be problematic. In this paper the serviceability assessment of floor vibration occasioned by walking activities is considered.Over 30 years ago concerns were raised regarding vibrations induced by walking on steel–concrete composite floors that satisfied traditional deflection criteria. In response to these concerns, design criteria based on a simple impulsive loading function from a person rising onto the balls of the feet, and suddenly dropping onto the heels has been used as a measure of floor acceptability. More recently, design procedures have been developed that more realistically consider the excitation of the floor from walking activities.In the first part of this paper a historical review of acceptability criteria for floor vibrations will be made. Following this, the current design methodologies for steel–concrete composite floors will be reviewed prior to the presentation of results from a series of in situ vibration tests on a wide variety of floor types. After comparing the test results with current guidance, design recommendations and suggestions for future research will be given.

Buckling of the steel component of a composite member caused by shrinkage and creep of the concrete component

AbstractThe effects of shrinkage and creep in conventional reinforced and prestressed concrete members are quite well understood, and the effects of these time‐varying characteristics of the concrete component on the deflections of composite beams and columns have received a good deal of attention in recent years. However, creep and shrinkage effects may cause a redistribution of internal actions within a composite member, which increases significantly the compression within the steel component, and that may therefore lead to considerations of the possible buckling instability of the steel component. This paper reviews the research work that been documented only quite recently, which has been undertaken on the potential for composite structures using a thin external skin with a concrete infill to buckle locally, and the possible instabilities that may arise in the negative moment region of a continuous composite beam, due to the shrinkage and creep of the concrete. This paper also puts the possibilities of these instabilities into a practical perspective, indicating where this unique type of steel buckling may need to be a design consideration in the most efficient use of steel–concrete composite construction.

Semi-probabilistic fracture mechanics approach for a quality assurance system for welds of a containment for a 1000 MW nuclear power unit

The paper deals with a quality control system based on: (1) limit stage design for a given level of failure probability ( P f≤10 −6), and (2) fracture mechanics requirements for welds, the heat-affected zone (HAZ), and parent material (St 355 E). This quality control system was carried out under on-site-conditions when building a steel-sheet/reinforced concrete composite construction of a containment for a nuclear power station. The basic element of the quality assurance system are the control welds produced simultaneously with the welds on site (manual electrode welding). The materials testing program of such control welds and statistical evaluation of test results are described. The results show a fairly good reproducibility of measured J-integral values of welds gained from on-site-specimens (control welds) and those obtained from pre-tested welding technologies. The objective of this paper is to encourage the application of the proposed semi-probabilistic fracture mechanics approach for cases, when the area of proven experience for designing and fabricating welded metallic constructions must be left. Some conclusions of practical interest are discussed, for instance: (1) restrictions for high-strength steels, resulting from the limitation of yield to ultimate tensile strength ratio ( R p0,2/ R m≤0.75) in the standards and regulations; (2) importance of demand for a portion of plastic component of the J-integral to exclude brittle fracture of welds; and (3) derivation of a fracture toughness criterion for application to high strength steels.

Research into composite tubular construction for offshore jacket structures

Abstract This paper describes recent developments in the use of steel and concrete composite construction for offshore structures. The developments concern filling steel tubular members with cementitious materials to improve static and fatigue strength of memebers and joints. Applications are described for jacket to pile connections, nodal joints and repair situations.