Applied Mechanics and Materials Vols. 752-753

Abstract: This paper reports on an experimental study on the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double skin cantilever beams (referred to as DSTBs) that were tested under reversed cyclic loading. The beams were manufactured using a high-strength concrete (HSC) mix and they were 150 mm in diameter and 1.2 m in length. The main parameters of the experimental study included the size of the inner steel tube and the use of mechanical connectors in the form of steel rings welded on the inner steel tube. Test results indicate that DSTBs are capable of developing a highly ductile behavior under reversed cyclic lateral displacement excursions. It is found that the addition of mechanical connectors on the steel tube has no significant influence on the lateral displacement capacity of the test specimens, but they can eliminate the slippage between the concrete and inner steel tube. Examination of the test results has led to a number of significant conclusions on the influence of the beam parameters on the performance of DSTBs, which are discussed in the paper.

Abstract: Recently, a new type of composite system was proposed in the form of fibre reinforced polymer (FRP)-concrete-steel double-skin tubular columns (DSTCs). The performance of this column system, which consists of an outer tube made of FRP and an inner tube made of steel, has been experimentally investigated in a number of studies. However, apart from a single study reported on square DSTCs, all of the existing studies have been concerned with DSTCs with circular external tubes. This paper reports on part of an ongoing experimental program at the University of Adelaide that was aimed at addressing this research gap. The effect of cross-sectional shape of inner steel tube on compressive behaviour of square DSTCs was investigated through the test of 16 hollow and concrete-filled DSTCs. The result of the experimental study indicate that concrete in hollow DSTCs with circular inner steel tubes develop significantly larger ultimate axial stresses and strains than concrete in companion hollow DSTCs with square inner steel tubes. On the other hand, the results also indicate that the presence of a concrete-filling inside inner steel tubes results in a significant improvement in the behavior of DSTCs with square inner steel tubes.

Abstract: The use of non-destructive inspection techniques in conventional stainless steels is well established. However the non-destructive inspection of duplex and superduplex steels is a big challenge as those steels, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. An extended research is proposed on the inspection of duplex steels, especially in welded joints, which presents the worst problems in those steels (incorrect ferrite/austenite balance and precipitation of deleterious phases). The aim of this work was to use the TOFD ultrasonic inspection method for the thin duplex steel weld joint inspection.

Abstract: This paper reports on the potential use of fly ash (FA) and residual rice husk ash (RHA) in producing unfired building bricks (UBB) with the application of densified mixture design algorithm (DMDA) method. In this study, little amount of cement (10–15%) was added into the mixtures as binder substitution. Whereas, unground rice husk ash (URHA), an agricultural by-product, was used as partial aggregate replacement (10–20%) in the mixtures. The UBB of 220×105×60 mm in size were prepared and the hardened properties of the bricks were tested including compressive strength, flexural strength, water absorption and bulk density according to Vietnamese standard. Forming pressure of 35 MPa was applied to form the solid bricks in the mold. The test results show that all brick specimens achieved very good mechanical properties. The compressive strength, flexural strength and water absorption of brick specimens were respectively in range of 16.1–22.1 MPa, 2.8–3.5 MPa and 9.5–14.8% and the other properties of the bricks were well conformed to related Vietnamese standard. It was definitely proved many potential applications of FA and RHA in the production of UBB.

Abstract: The article deals with the numerical-analytical method of solving problems in the theory of elasticity of inhomogeneous bodies in terms of displacements for a circular cylinder. We consider two-and three-dimensional problems. After separation of variables, the problem is reduced to the numerical solution of the system of differential equations of the first order.

Abstract: The paper studies the efficiency of seismic isolation system in the form of rubber-metal bearings with different height buildings at multicomponent seismic impact. As an example, seismically insulated monolithic reinforced concrete 5-, 9-and 16-storey buildings are considered. The solution of the problem is obtained by a direct integration of the motion equations for an explicit scheme in the software package LS-DYNA. The calculation is performed considering nonlinear nature of rubber bearings. The analysis of the effectiveness of buildings with seismic insulation and without it is performed.

Abstract: Crack is a common cause of the degradation of concrete and may affect its structural durability. In order to ensure the bridge is safe utilized in anticipated period of their future service, a proper maintenance process and procedure should be taken. Therefore in this study, static load test were performed on a pre-tensioned (PRT) concrete beam to investigate crack behaviour before and after retrofitting process as well as to determine the effectiveness of the retrofitting method. A control beam named PRTB1 will fully loaded until fail to determine its maximum load capacity and critical load of the beam. Hence another beam named PRTB-FRP will be loaded until it reached it critical load capacity before retrofitted using Fiber Reinforced Polymer (FRP) plates located beneath the centre of the beam. After the retrofitting process PRTB-FRP will be put again under the static load. The load capacity of PRTB-FRP increased compared to PRTB1 with some improvement in crack propagation behaviour after retrofitted.

Abstract: There has been much research conducted on the current performance of Fiber Reinforced Polymer (FRP) as reinforcement. It was due to FRP easier to maintain than steel during construction because of less weight. Laboratory works on the flexural behavior of concrete beams that with GFRP and CFRP use as a plate strengthening for the beam size 2800 x 200 x 250 millimeter. study of the pattern of cracking and failure modes of the beam will be compared between the ten types of beams consisting of steel reinforced beams , beam-reinforced GFRP and GFRP reinforced beams strengthened with CFRP with different lengths. Comparing between the beam bending performance was examined through the ultimate load, cracking and failure modes.

Abstract: The algorithm taking into account the concrete creep and changes of its modulus of instantaneous elasticity is defined. Such algorithm was based on formulas obtained by Harutyunyan (Harutyunyan, 1952). The program with the time factor taking into account both the specified events and the sequence of frames erection in a monolithic design was made.

Abstract: This paper investigates the finite element modelling of the temperature distributions of reinforced concrete slab using a general purpose non-linear finite-element program, ABAQUS. The reinforced concrete slab is tested under exposure to designed fire in order to validate the shell element in in the ABAQUS program. The modelling results showed agreement with the fire test and it demonstrated that the ABAQUS shell element can be used to predict fire behaviour within reinforced concrete slab in elevated temperature conditions.