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The pseudo-static tests of one RC squat shear wall without opening and the other three RC squat shear walls with different arrangements (center, bottom, and top) of a single post-opening, reinforced by bonding steel plates, were carried out to simulate the defects caused by the post-opening at different locations and investigate the effect of post-opening location on the seismic performance of reinforced squat shear walls. The corresponding models of the tested specimens and also the other three models of the RC shear walls with the same opening and without any reinforcement were analyzed with Abaqus software. Results indicated that the shear wall without opening and the reinforced shear walls with a single post-opening show flexural shear failure. The relative difference between the bearing capacity of the three reinforced specimens and the reference specimen is not more than 6%. The average displacement ductility coefficients of reinforced shear walls with the central and bottom openings were reduced by 9.62%, while that of reinforced shear walls with the top opening was increased by 23.01%. FEA further reveals that the steel plate significantly reduces the uneven distribution of the reinforcement strain around the opening for shear walls with different post-opening locations. [ABSTRACT FROM AUTHOR]

In recent years, aluminium alloy became an emerging construction material. In order to repair or strengthen the wood beam with an appropriate material, six timber beams reinforced with different thicknesses of aluminium plates and connections between the timber beams and aluminium plates were tested in this article. To investigate the ultimate bending capacity of timber beams which were reinforced using the aluminium plates with the thicknesses of 3 mm and 8 mm, the influences of adhesive, screw, adhesive and screw on the beading capacities are studied. The ultimate bending capacity of timber beams reinforced using the aluminium plates with the thicknesses of 3 mm and 8 mm was investigated. Three plain timber beams were also tested for the comparison. An analytical model has been developed for predicting the ultimate bending capacity of the timber beam reinforced with aluminium plate by using the adhesive and screw together connection. The results indicate that the initial bending stiffness and ultimate bending capacity of the reinforced timber beams can be enhanced obviously. Compared with the beams without reinforcement, the initial bending secant stiffness of the beams reinforced with aluminium plate was enhanced by 109% maximally and the average increase was 55%. The ultimate bending capacities of the beams reinforced with aluminium plate were enhanced by 57% maximally and the average increase was 30%. The most effective way to enhance the ultimate bending capacity of the reinforced timber beam is to use the adhesive and screw together connection. The strain distributions along cross section of the timber part of the reinforced beam were approximately linear. [ABSTRACT FROM AUTHOR]

The early-age mechanical properties of ordinary concrete after a thermal cycle are investigated in this paper, to provide information on the residual safety of concrete structures after a fire occurred during the construction phase. The specimens are heated up to 150, 350 and 550 °C, from 3 to 28 days after casting, and tested in compression and in splitting tension after a rest period. The effects of curing period before heating, exposure temperature, cooling methods (in sprayed water or in air) and of the rest period prior to testing are investigated. The rest period after a thermal cycle performed at an early age brings in a marked recovery in terms of final residual compressive and tensile strengths. More than 50–60% of the loss may be recovered which is much lower than that documented in recent studies on fly-ash concrete. The lowest recovery is exhibited by the concretes exposed to high temperature at 7th day. Extending the rest period increases the strength recovery. For the concrete heated at 3rd, 7th and 14th day, cooling the specimens in sprayed water lead to larger strength recoveries than in air, both the strengths immediately after cooling and that after rest periods. [ABSTRACT FROM AUTHOR]

This study investigated the effects of elevated temperature and cooling method on the compressive strength and carbonation depth of concrete specimens which were re-cured for different durations. The concrete specimens were heated to different temperatures up to 750°C and were then cooled in air or by spraying with water. After cooling to room temperature, the specimens were post-fire cured in a controlled environment for a total duration of 90 d. Compressive strength and accelerated carbonation tests were conducted to measure the changes in the compressive strength and carbonation depth of the concrete specimens. The experimental results indicate that the compressive strength of air-cooled concrete exposed to temperatures of 150, 300 and 450°C reached respectively 101·6%, 97·2% and 81·9% of the original values. However, after exposure to temperatures of 600°C and 750°C, the compressive strength of the air-cooled concrete decreased to 40·4% and 26·2% of the original values respectively. The compressive strength values of water-cooled concrete heated to 150, 300, 450, 600 and 750°C gradually changed to respectively 102·7%, 96·7%, 80·2%, 46·9% and 28·7% of the original values. The carbonation resistance of concrete was not recovered for concretes exposed to temperatures above 450°C and the carbonation resistance of the water-cooled concrete was lower than that of air-cooled concrete. After exposure to a temperature of 600°C, similar variations were observed in concretes with water-to-cement ratios of 0·55 and 0·35. [ABSTRACT FROM AUTHOR]