Applied Mechanics and Materials Vols. 166-169

Abstract: Simple-supported reinforced concrete (R.C) beams are subjected to an increasing static load in the middle to introduce cracks, and the last load step corresponds to failure. After each load step and unloading, an experimental dynamic monitoring is performed. Multiple degree freedom dynamic equation of the test beams is wavelet transformed, and structural dynamic response expression on multi-scale is acquired. It’s shown that multi-scale decomposition of signal comprises more structural damage information. By means of DASP signal processing system, binary wavelet transformation is applied to dynamic signal of reinforced concrete beams on different damage state. Through analyzing wave-figure of all frequency scales, the damage of reinforced concrete beams is detected.

Abstract: Based on the test，the shear behavior of combined aggregate concrete beams is studied. The results show that combined aggregate concrete beam have similar behavior with ordinary concrete beams, and the shear capacity reduces with the increase of lightweight aggregate. And design formula of the combined aggregate concrete shear capacity is suggested.

Abstract: Bamboo is widely used in building construction in south China. However, Termites are the natural enemies of bamboo building. Therefore, the inhibition effect of extractives on building bamboo’s termite prevention was studied. The results shown that the benzene / ethanol extractives of camphor tree roots, camphor leaves,Cedrus deodara leaves needles, and torch pine leaves had the better toxic effect to termites among the 15 extractives.

Abstract: In the issue of oil storage tank, the method of corresponding oil volume is solved in different height of oil by differential coefficient.In actual oil storage amount in tank and height of oil, deflexion issue in three dimension is transformed to equal area issue in two dimension.The function relation is set in different variable quantity.

Abstract: On the basis of the Australian Computer Society(ACADS)`s typical questions1(a),first, regardless of the slope in the case of pore water pressure, used FLAC procedure calculate the safety factor, the result was very close to the reference answer given by ACADS, we can see the accuracy of FLAC. Then, applied to the slope of different pore water pressure, obtained safety factor under corresponding conditions, then, we found that the pore water pressure had effect on the slope safety factor, but the influence are not same, when the pore water pressure less than a certain value, the influence are very small, but, when the pore water pressure exceeded this value, the influence became very large.

Abstract: In indirect detecting, the measure value and the measured value are not the same or there is not a determined relationship between them, the measure physical value has to be surmised according to the measured value from statistics principals. Based on traditional and failure detecting method, the assessment methods of two different test conditions are deduced by the whole presumption method, theoretical formula of the confidence intervals, the method of probability and statistics. Moreover, the standard of qualification or unqualification is presented. The examples of engineering have shown that concrete strength is judged qualification with high probability. This method is used not only in test of building structure, especially in the evaluation of earthquake, but also popularizes to other domains, strength detecting for bridges, the pressure vessel, aircraft wing etc.

Abstract: The microstructure and mechanical behavior of welded joints under different technologies were compared for investigating the influence of technological parameters on microstructure and property of weld seam on thick-walled cold-rolled-forming high frequency induction welded (HFIW) tubes. The results show that microstructure of joints consists of a decarburized layer, an overheated area, a recrystallized zone and a partially-recrystallized zone. The opening angle and the welding surface energy (WSE) are important factors affecting microstructure and weld quality. The width of the heat-affected zone is proportional to the WSE. With increase of the WSE, the mean bend angle increases first and decrease later, showing a "mountain-peak" variation. The optimum WSE decreases with decrease of the opening angle because the smaller the opening angle is, the higher the heating efficiency is. The influence of processing parameter on the bending capability of joints is remarkable, while which on the impact toughness can be ignored.

Abstract: Reinforced concrete (RC) structural walls are one of the most commonly used lateral load resisting systems for high-rise buildings in strong seismic regions because of its good lateral resistance. Serious damage occurs when RC structure subjected to strong seismic action. Classified and brief comment of documents concerning damage indices and its calculation methods are conducted. It could be concluded that most of the damage evaluative models can not directly consider the effect of cumulative damage of material to mechanical properties of structure. Suggestions are proposed to improve the accuracy in damage evaluation of RC structure.

Abstract: In order to research the effect of stirrup ratio on ductility and bearing capacity of T-shaped columns with HRB500 reinforcement, three T-shaped columns with HRB500 reinforcement were tested under low cyclic loading. The damage characteristic, hysteretic curve, yield load, ultimate load, displacement ductility and curvature ductility were analyzed. It is shown that the T-shaped column with HRB500 reinforcement have excellent ductility, higher bearing capacity and better deformation behavior, which can meet the requirement of anti-seismic design. With the increase of stirrup ratio, the curvature ductility of T-shaped columns with HRB500 reinforcement increases and the hysteretic behavior improves.

Abstract: The relation between stress and strain of masonry material under uniaxial monotonic condition is analyzed and the initial elastic stage is proposed for elastoplastic analyses. Furthermore, plastic damage model and elastic module degradation with plastic strain are investigated. The model describes the effects of irreversible damage: elastic module is fully determined by accumulated plastic strain; compressive stiffness may be recovered during cyclic loading. Based on the model, elastic module degradation and incremental stress-strain equations under multiaxial loading are discussed. Finally masonry shearwall under invariable compressive loading and monotonic shear loading is calculated, and plastic tensional strain before crushing is shown.