Finite Element Analysis of Mechanical Behavior of High Strength Bolt Friction Grip Long Joint

In order to study the mechanical behavior and stress state of the high strength bolt friction grip long joint, fourteen different bolted connections are studied with the three-dimensional finite element analysis which is based on the general FE software ANSYS. The force-delivering ratio of each bolt, the stress concentration at the edge of the bolt hole, the stress state of the high strength bolt and the force-delivering coefficient before the bolt hole are specially studied. Also, the ranges of these parameters’ value are presented clearly. The results presented would be useful as references to these type joint's design and computation.     

Experimental Study of Ratio Between Splitting Tensile Strength and Compressive Strength for PVA Fiber Cementitious Composites

An experimental study of the splitting tensile strength and compressive strength were carried out. Effects of PVA fiber was analyzed on ratio between splitting tensile strength and compressive strength. The dimensions of cubic specimens were 100 mm×100 mm ×100 mm. PVA fiber were added at the volume fractions of 0, 0.5%, 1%, 1.5%, 2% and the fly ash content were 30%, 50%. The test results indicate that, the compressive strength varies very little after incorporation with PVA fiber, however, the splitting tensile strength increases from 42.64% to 135.12% and the ratio between splitting tensile strength and compressive strength increases from 36.82% to 134.27%. What's more, the compressive strength of cementitious composite including fly ash at the ratio of 30% is 20% higher than that of 50%,and there is no obvious improvement on the splitting tensile strength with the change of fly ash content. This paper also shows that the compressive test cube of PVA fiber cementitious composites has multiple cracks and is hardly crumbled in the degradation process, and then the compressive toughness can be enhanced significantly.     

ANALYSIS OF THE BEHAVIOUR OF HIGH STRENGTH BOLTED SHEAR CONNECTIONS

On the basis of experimental tests,a formula is proposedfor the computation of the load-deformation curves of the single highstrength bolted connections in axial shear forces,which is a piecewisefunction describing three stages of friction,slipping and bearing of theconnections,and is also suitable for the non-slip connections.The limitstate method is used to compute the behaviour of high strength boltedconnections subject to eccentric shear,in which each bolt obeys thenon-linear relationship aforementioned.In this paper,the computer pro-gram is worked out to solve the non-linear problems.Analytical resultsare shown to be in general good agreement with experimental data.     

不同拉伸速度对卷烟纸纵向抗张强度和伸长率检测结果的影响

用统计学的方法对比了不同拉伸速度对卷烟纸纵向抗张强度和伸长率的检测结果。结果表明,在拉伸速度分别为15,17,20,22,25 mm/min时,各试验组内检测结果无显著性差异,稳定性均较好;在拉伸速度为15～25 mm/min,不同的拉伸速度对卷烟纸纵向抗张强度检测结果无显著性影响,一致性较好;不同的拉伸速度将会对卷烟纸伸长率检测结果产生显著性影响,应在检测报告中注明拉伸速度;若要保证检测结果的一致性,应选择能使检测结果无显著性差异的拉伸速度进行检测。     

Study on Anchorage and Failure Mechanism of Mortar Bolt

Anchorage system can transfer or enhance intensity and steady ability of the geotechnical project. Based on the simplification of a project, the process of anchorage and failure of bolt is simulated in laboratory. The analytical expressions of stressed bolt in elastic rock under axial symmetry condition are deduced. The pilot study of the relativity of anchorage stress and acoustic parameter is discussed by ultrasonic transmission way in this paper.     

An Analysis to the Force Property of the Clutch-Screw Press and its Strength Design

This paper deals with the force property analysis,strength design and use of the clutch-screw press.     

我国蒜薹产业2010年回顾和2011年展望

从2010年全国各主产区蒜薹收购价格比较及收贮与销售蒜薹情况的回顾,分析了气候、蔬菜市场、大蒜种植等影响我国蒜薹产业经营状况的主要因素及存在的问题,展望了2011年蒜薹产业的发展前景.     

蒜薹贮藏保鲜工艺及常见问题

蒜薹是我国北方冷库贮藏蔬菜的主要品种,在我国果蔬贮藏保鲜业中贮量大、供应期长、经济效益好。简述了蒜薹贮藏保鲜工艺、常见问题及解决办法,以期为蒜薹保鲜技术的研究以及蒜薹贮藏保鲜业提供参考。     

Experimental Research on Mechanical Behavior of High-strength Concrete Short Columns Confined with Stirrups

Based on the test of high strength concrete (HSC)short columns confined with stirrups 8 under axial loads and 6 under small eccentric loads, the influence of stirrups confinement on stressstrain relationship and related parameter under monoaxial compression are studied, and the effect of the type of stirrups, stirrup ratio, etc. on the HSC columns ductility is analysed. Besides, the strength and deformation behavior of HCS columns under small eccentric compression are explored.Based on the experimental study, the complete stress-strain curves of confined HSC and the formula for calculating the related parameter are presented in this paper.     

Experimental Analysis of Rotational Behavior of Timber Beam-column Connection of Ancient Tibetan Architecture

Static experiment was carried out to study rotation behavior of timber beam-column connection. The influence of length of Gongmu and position of dowel on the initial rotational stiffness of the joint was analyzed. Rules of stiffness degradation under cyclic loading were studied as well. The results show that: the moment-rotation curve of typical timber beam-column connection can be simplified as bilinear model; the initial rotational stiffness of the joint is enhanced with the increase of the length of Gongmu, and it is decreased with the inward movement of dowel; under the same conditions, the influence of the inward movement of Gongmu-beam dowel on the initial rotational stiffness of the joint is smaller than that of Dianmu-Gongmu dowel; and stiffness degrades under cyclic loading and there exists obvious transition phenomenon.     

Analysis on the Behavior of Diaphragm Through Connection between Steel Beam and Concrete-filled Steel Tubular Column

Diaphragm through connection is a new kind of connection between steel beam and concrete-filled steel tubular column. Quasi-static test and numerical simulation had been carried out to investigate the behaviors of diaphragm through connection used in Zhonghai Square. The results show that, the bearing capacity, rigid and ductility of the diaphragm through connection are excellent, and the seismic principle, i.e., ‘strong column but weak beam’ and ‘strong connection but weak component’, is reached. The numerical model of diaphragm through connection was provided, and the results drawn from the model agreed with the test results. Influences of diaphragm dimension on the behaviors of the diaphragm through connection with praposed the numerical model had been investigated, and the design suggestion was provided based on the analysis.     

Application of FEM strength reduction method to geotechnical engineering with the consideration of tension and shear failures

The failure characteristic of geomatertials in different stress states is analyzed, and it is found that the stability of geotechnical structure depends on not only shear strength index c and tanφ, but also tensile strength index T. The overvalued of tensile strength of materials could lead to non-conservative results in the primary strength reduction method. Therefore, the FEM strength reduction method should take identical reduction of both tensile strength index and shear strength index into account. In other word, tension and shear strength reduction method (TSSR) in the process of strength reduction should be adopted. The necessity and correctness of TSSR is validated by stimulating four typical example models, i.e. the general slope, the stalactite, the tunnel and the steep slope. Studies show that the modified strength reduction method has universal applicability in geotechnical engineering.     

Design Method for Bending Buckling of Web in Aluminum Beam

As for the local buckling of aluminum bending members, a finite element analysis of the stability of aluminum plates under bending was performed. Compared with the results of codes’ method and finite element method, the advantages and disadvantages of existing codes were discussed. Base upon the results of simulation, the relevant design formula in Code for design of steel structures (GB50017) were modified with the reference of existing foreign codes. And the design methods were proposed for buckling strength and post buckling strength of aluminum plates under in plate bending. It was found that the results of proposed methods were in high accuracy and safer condition, and suitable for the stability design of aluminum plates under in plate bending.     

蒜薹炭疽病病原鉴定及其生物学特性研究

为了明确引起蒜薹炭疽病的病原菌种类及其主要生物学特性,从河南新乡发病蒜薹上分离到一株炭疽病菌,依据病菌的形态特征、培养性状和致病性测定等进行鉴定,并进行病原生物学特性研究。结果表明,该蒜薹炭疽病菌是胶孢炭疽菌（Colletotrichum gloeosporioides (Penz.) Sacc.）。该菌菌丝生长的温度范围为10~35℃,最适25℃;菌丝生长的适宜pH范围为3~7,最适pH 7。分生孢子萌发的温度范围为10~40℃,最适30℃;分生孢子萌发的适宜pH范围为4~7,最适pH 6。分生孢子在饱和湿度萌发率最高,相对湿度低于90%时不能萌发。光暗交替最有利于菌丝的生长,黑暗条件有利于分生孢子的萌发。本研究是首次报道了引起蒜薹炭疽病的病原菌为胶孢炭疽菌。     

钙化条件对海藻酸钙膜钙含量和拉伸强度的影响

采用不同钙源制备海藻酸钙膜,根据膜的钙含量和拉伸强度确定了钙源的种类、钙化温度、钙化时间和钙化浓度。结果表明,在钙源选择氯化钙,钙化溶液的温度选择40℃,钙化时间选择20 min,钙化质量分数选择3%时,得到的海藻酸钙膜的钙含量最多、拉伸强度最大,并且膜拉伸强度的变化趋势与钙含量变化趋势基本一致。     

Bolt shotcrete support and small pipe groutingtechnology used in treating tunnel collapse

Bolt shotcrete support and small pipe grouting technology are two important elements in the new Austrian tunneling method. We explore the application of bolt shotcrete support and small pipe grouting technology in treating the Huanshanping Span Tunnel col     

Parametric Analysis of the Static Behavior of Gusset Plate to CHS XX joints

A parametric analysis was carried out to investigate the gusset plate to CHS XX joints with the finite elements method. The effects of web loading proportion, geometric parameters and axial stress in chord on the failure modes and the ultimate strength were employed. It is found that the web loading proportion have different effects on the ultimate strength with different angles between two gussets. And the ultimate strength of joints decreased no matter the axial stress in chord was positive or negative. Based on the regression analysis, a formula was proposed for predicting the ultimate strength of the gusset plate to CHS XX joints.