Post-fire strength of austenitic stainless-steel T-stubs with four bolts per row

For connections made with carbon-steel, the behaviour of the T-stub component is well understood and documented in the Eurocodes and is applied to T-stubs with two or four bolts per row. Researchers have investigated the application of the same Eurocodes guidance to T-stubs made with stainless-steel and having two and four bolts per row. However, there is very little information or studies on the post-fire behaviour of stainless-steel T-stubs and none found for those with four bolts per row. This study is aimed at providing a fundamental understanding of the post-fire behaviour of this connection component. Finite element analyses were carried out on 190 specimens with different parameters including temperature, T-stub flange thickness, width and strength, bolt diameter and grade, bolts spacing and edge distance. The results indicated four failure modes that are possible for the post-fire austenitic stainless-steel T-stub with four bolts per row. In all specimens, no circular yield patterns were recorded but only beam patterns occur at the web-flange intersection and at the bolt locations. A design approach for calculating the post-fire plastic resistance is proposed by introducing new and simplified formulas for determining the effective length of the plastic hinges for the various modes of failure. The accuracy of the design approach was validated using finite element modelling and experimental data from the literature

Flexural Behavior of Concrete Composite Beams with New Steel Tube Section and Different Shear Connectors

Hollow sections of steel are widely used in many engineering applications as structural members. This paper aims at studying the flexural behavior of a composite beams with steel tubes sections through a series of bending tests in order to study and examine the influence of the steel tube section shape, (square, rectangular and hexagonal) with the same shear connector type (headed stud or angle or perfobond) on its flexural behavior and the bending properties of these sections. As well as study the effect of different shear connectors types (headed stud, angle and perfobond) in the same steel tube sections (hexagonal, square, or rectangular) on the flexural behavior of the composite beams. The experimental program (in this work) has been divided into two groups, the first consists of nine specimens tests focusing on three types of steel section. Using shear stud first, angle at second, and perfobond at third as shear connector type. The second group consists of testing nine specimens of composite beams too. This group focuses on testing every steel section (hexagonal, square and rectangular) alone when using three types of shear connectors with it. All the specimens are of the same length, width and height (2000, 400 and 130) mm respectively. The tested steel tubes thickness was 2 mm, yield stress of 322 MPa and the ultimate strength was 390 MPa. The results showed that these shapes of hollow steel sections (hexagonal, square and rectangular) sustain the quality of services for the buildings, and these tested specimens are applicable by giving a distinctive strength and stiffness starting from 114 kN as ultimate load reaching to 170 kN. The experimental results proved that the perfobond and angle connector types are clearly effective shear connectors. Shear connector of the perfobond type increased the ultimate load of the composite beams by (6.25-9.74) % compared with the stud shear connector

Flexural behavior and sustainable analysis of polymer bubbuled reinforced concrete slabs

This work presents the flexural capacities and sustainable analysis of reinforced concrete (RC) two way hollow slabs with polymer sphere voids, also known as polymer bubbled RC slab system. A polymer bubbled RC slab has two-dimensional arrangement of voids included to reduce the self-weight. The strength and behavior of bubbled RC slabs with polymer spheres voids is investigated experimentally. Eleven RC square slabs of 1000mm x 1000mm dimensions have been tested to obtain the flexural behavior. Variables of the experimental work are: diameter of polymer spheres, thickness of reinforced concrete slabs, and percentage of Metakaolin (cement replacement). It has been found that bubbled RC slab, (with ratio of bubble diameter B to slab thickness H, B/H=0.51 to 0.80), has about (90 to 100%) of the ultimate load capacity of a similar reference solid slab (which has the same slab thickness). Also, bubbled slabs consume about (70 to 75%) of the concrete needed for the similar solid slab. An increase in the deflection at 0.7