共查询到20条相似文献，搜索用时 406 毫秒
1.
Theoretical and Experimental Analysis of Bending Behavior of Composite Beam with Notched Web 总被引：2，自引：0，他引：2
A new kind of steel-concrete composite beam with notched web is proposed, and the bend and shear behaviors of this composite beam are investigated. First of all, the constitution, bearing characteristics and merits of the steel-concrete composite beam with notched web are introduced; then, a group of formulas about the bending capacity, slip between the steel beam and the concrete flange, and the deflection are introduced; after that, the bending behavior, slip effect and bearing characteristic of the steel-concrete composite beam with notched web are studied on 4 specimens, which are tested by applying two concreted vertical loads on the top of concrete flange. And the finite element model is adopted to analyze the results of the 4 specimens; finally, the reliabilities of the formulas are verified by comparing the results of theoretical formulas, the results of tests and that of finite element analysis. Study shows that the bend behavior and shear behavior are fine, and the popularization of this new kind of composite beam which can be broadly used in building engineering will save the consumption of steel. 相似文献
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There are obvious geometric nonlinear mechanical characteristics in new type arch bridge with diagonal web cables. Meanwhile, the convergence of the existing arch axis iterative optimization method is not good. In order to solve new type arch bridge axis iteration convergence problem considering geometric nonlinear mechanical analysis, an arch axis iteration optimization method was proposed based on the iteration basis finite element model with two hinge arch model in main arch ring. A 600m span arch bridge with diagonal web cables was selected as an example to test the convergence performance and applicability of proposed method. The results showed that the bending moment of proposed method had better distribution along arch span, and it is about 35% smaller in maximum bending moment, 17% smaller in minimum bending moment and 23% smaller in bending strain energy compared to the results of linear iteration optimization method. Convergence analysis results demonstrated that proposed method had better iteration performance than the existing method. Meanwhile, different initial arch axis can converge to stable results. 相似文献
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Based on the simplified elastoplastic constitutive model of soil, the calculation method for the laterally loaded single pile with large deflection was submitted. The coefficient of subgrade reaction was presumed to increase linearly with depth, which simulates the soil resistance close to ground well. The relevant program was then developed using FORTRAN language. The examples show that (1)the displacement and bending moment increase nonlinearly when the lateral load and the moment load increase. (2)The pile displacement decreases with depth. (3)The pile displacement at the point which is over ten times pile diameter from ground is so small that can be neglected. (4)The pile head condition is the key factor, which influences the distributions of pile responses along depth. (5)By improving the mechanical properties of soil around pile, the maximum lateral displacement and bending moment can be decreased efficiently. The calculation results are in good agreement with the field test results and are better than those obtained using the pre existing solutions, which shows the presented solutions are reliable. 相似文献
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ABSTRACT Several recent studies have challenged the conventional notion that raising the minimum wage has negative labor market consequences. In particular, most recent minimum wage research has considered teen employment, with virtually no examination of unemployment rates. Given the conflicting findings in the recent literature, this study reconsiders this issue by examining the minimum wage's influence on teen unemployment rates. The empirical analysis considers state data from the latter 1980s, a unique period where many states raised their minimum wage above the federal level. The results suggest that both a greater minimum wage rate and greater minimum wage coverage increase teen unemployment rates. Further evidence suggests that employment declines outweigh teen labor force reductions, suggesting that increases in unemployment are primarily caused by labor demand shifts. Thus, policy makers should weigh these costs in deciding future minimum wage hikes. 相似文献
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Chlorides in the wastewater with high salt seriously interrupts the determination of chemical oxygen demand(COD). Therefore, chloride mask in wastewater has been an important and difficult issue in recent years. In the present work, experiment design is used for more accurate and precise COD determination method of pickled mustard wastewater. Two methods for masking chloride are adopted: HgSO4 masking method and AgNO3 masking method. After masking chloride, use the traditional reflux digestion method to test COD in the experimental sample. The results show that when the ratio of HgSO4 to Cl - is 40, the chloride mask results in a minimum error of 1.43%, and the minimum error is 0.21% when AgNO3 is used. Obviously, AgNO3 masking method is superior to HgSO4 masking method. However, when these two methods are used in pickled mustard wastewater, there is a COD value difference of 20 mg/L and HgSO4 masking method is more accurate. By considering the characteristics of the two methods above, a combined method is proposed, which AgNO3 is added equivalently according to the concentration of Cl - first, and then a few amounts of HgSO4 are added to prevent the free Cl - in wastewater. The facts show that combined method is more reliable. 相似文献
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This paper presents the experimental results of 9 specimens.The mainobject of this experiment is to study the aseismatic behaiour of wide-shallowcoupling beams.Several variables that exert main influence on the behaviourare considered.Also,some aspects concerning the specific design are proposed. 相似文献
7.
This paper ainalyses the size effect of the fracture energy of concrete tested bythree point bending. It is shown that positive errors of test results of fracture energy increase,ornegative errors decrease with increasing of the specimen ize. The phenomenon is one of main causesresulting in the size effect of fracture energy. 相似文献
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Bai Shaoliang Zhu Xijun 《保鲜与加工》1990,(1)
In this pager, four full-scale corner joint assemblies of reinforced concrete frame beam and column with different detail structure are tested under low cycle loading, The process of damage development and the characteristics of break of the assemblies in the course of alternately increasing positive and negative bending deformation are learned Strength, stiffness and ductility of assemblies and the various regulations of energy consumption are also studied. Compared with these properties, the anti-seismic behavior is tentatively commented. Besides, the test results of the strain distribution of beam and column longitudinal bars and stress state of joint stirrups are analyzed. 相似文献
12.
Sun Renbo Wang Daiyu 《保鲜与加工》1988,(4)
In this paper, the solution of cylindrical bending problem for rectangular plates supported by elastic and tensile supports on particular deformation condition are derived from practical engineering problem. By examples, some considerable matters of analysing prismatic structures are suggested. The solutions are also studied when the tensions are to be determined. the results are simple and easy to be used. 相似文献
13.
The structure of wedge flash is proposed to improve the filling properties for deep cavity structure of crankshaft die with dimensional splitting mold. BP genetic algorithm is applied to optimize the structure parameters of wedge flash based on Matlab. Samples which are selected by orthogonal test are analyzed via FEM, and the minimum unfilled distance obtained are employed to conduct the BP neural network training. Then the optimum parameters with minimum unfilled distance are gained from genetic algorithm. Error between the parameters predicted and the results get from simulations is less than 5%. The productive practice indicates that the cavity is fully filled and the material utilization ratio increases from 75.7% to 81.4%, which confirms the correctness of optimization of wedge flash structure. 相似文献
14.
磷化氢环流熏蒸技术在高大房式仓中的应用 总被引：2，自引：0，他引：2
在高大房式仓中进行了磷化氢环流熏蒸试验，同时研究了不同仓型和不同熏蒸方式存在的差异。结果表明，在仓房容量、风道设置、环流设置配置合理的条件下，能在较短时间内使磷化氢气体在仓内各部位分布均匀，最低浓度与最高浓度比值最小为0．5，大部分比值在0．8－0．9之间，均高于国外资料推荐的PH3环流熏蒸浓度均匀性标准，即大于0．25。保持有效杀虫浓度的时间长，能够杀死仓内粮堆中的储粮害虫，取得了良好的杀虫效果。 相似文献
15.
Based on a prestressed concrete girder with complex box-type section of 36m span, four models of 1/6 scale are made, and one of them is mixed with a kind of polymer latex. Experiments with monotonically and cyclically loading are carried out on the models to study bending fatigue behavior of the girder in service and under cyclic load exceeding the designed value, as well as the impact of polymer on fatigue performance of the girder. The results show that, under the cyclic load of value determined by the maximum and minimum stress at the key part of the girder in service, the fatigue performance is satisfactory and the fatigue behavior under a subsequent larger cyclic load is similar with that one under the same big cyclic load. Besides, the polymer has no negative effect on fatigue behavior of the model. 相似文献
16.
In order to accelerate the working speed of a FFT processor, this paper presents a hardware structure of a FFT processor, which is suitable for CPLD , and the 128-point FFT single-chip processor is realized by means of FLEX10K CPLD and MAX+PLUS II software. The calculation time of the processor is less than 230uS. The research proves that the combination of CPLD and FFT increases the working speed of FFT processors and raise the level of application . 相似文献
17.
On the basis of the calculated results of accurate analytic solution of stiffened rectangular plates,the general equations of cylindrical bending of the plates with tensile forces are established for engineering practice.Its solution combining with engineering problem is given for the special defor-mation conditions of elastic supports.In the paper,the numerical example is given and compared with references,it shows that the results are available. 相似文献
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Zhang Deshan 《保鲜与加工》1988,(2)
This paper suggests a calculation formula for eccentrically loaded brickwork or column with biaxial bending in terms of ultimate strength design method. The coefficients of the formula, are compiled as design charts so that the formula can be directly used for design of this kind of structural members. 相似文献
20.
Experimental study on acoustic emission characteristics of coal rock at different confining pressure 总被引：1，自引：0，他引：1
This paper conducts experimental investigation on acoustic emission(AE) characteristics of coal rock at uniaxial and triaxial compression by MTS815 rock mechanics test system. The results show that the variation of AE has tendency effect at uniaxial compression and confining pressure experiments. We indicate that AE signal decreases significantly in the elastic stage, and the relatively quiet period of AE before the specimens failure is not obvious under confining pressure. The AE amplitude distribution with time and its envelope line can indirectly reflect the trend of stress. The AE events peak stress and elastic modulus decrease with the temperature increase, and the value of m which reflects the cumulative distribution of amplitude increases as the confining pressure rises. The results also show that the AE frequency distributes in three frequency domains, and the proportions of dominant frequency significantly increase while the specimens are broken. 相似文献