共查询到20条相似文献，搜索用时 31 毫秒
1.
INTRODUCTIONTensionedmembranestructuresaremostsuitableforuseasroofstructureforavarietyofbuildingtypes,astheyprovidealight,elegant,andefficientstructurespanningoveralargeclearspace (Otto,1 973 ) .Examplesincludegymnasi ums,exhibitioncenters ,concertpavilio… 相似文献
2.
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｂｕｒｉｅｄｐｉｐｅｌｉｎｅｃａｎｂｅｃｌａｓｓｉｆｉｅｄｉｎｔｏｔｈｒｅｅｄｉｆｆｅｒｅｎｔｔｙｐｅｓ .Ｄｕｅｔｏｔｈｅｄｉｆｆｅｒｅｎｃｅｏｆｔｈｅｒｅｌａｔｉｖｅｓｅｔｔｌｅｍｅｎｔｂｅｔｗｅｅｎｔｈｅｐｉｐｅａｎｄｔｈｅｓｏｉｌｃｌｏｓｅｔｏｉｔｓｔｗｏｓｉｄｅｓ ,ｔｈｅｖｅｒｔｉｃａｌｐｒｅｓｓｕｒｅｏｎｔｈｅｐｉｐｅｖａｒｉｅｓｄｉｆｆｅｒｅｎｔｌｙ .Ｗｈｅｎｔｈｅｆｉｌｌｉｓｈｉｇｈｅｎｏｕｇｈ ,ｔｈｅｖｅｒｔｉｃａｌｐｒｅｓｓｕｒｅｉｓｔｈｅｍｏｓｔ… 相似文献
3.
针对港口集装箱岸桥吊具的电缆因岸桥吊随动系统不太可靠,使电缆频繁跑出电缆筐,直接影响岸桥吊作业的现状,使用PLC和丹佛斯VLT5022变频器组成的自动控制系统对其进行改造,较好地优化了港口集装箱岸桥吊具系统功能,提高了作业效率． 相似文献
4.
This paper introduces a formula for the vertical pressure on a buried pipeline by using a modification of the basic assumptions
of Marston’s theory. The fill’s cohesion is considered. The included angle between the slide surface above the pipeline and
the horizontal surface is assumed to be equal to the fill’s angle of friction. The friction is calculated by multiplying the
active earth pressure on the outer column and the coefficient of the friction on the slide planes It was found that the fill’s
cohesion had important influence on the vertical pressure, whose vertical pressureC
c decreases with increase of the fill depth, a relationship according with that observed in practice. At the end of the paper,
the formula is employed to analyze a practical case.
Project (No. RC9609) supported by Natural Science Foundation of China (NSFC) 相似文献
5.
Stay cables, the primary load carrying components of cable-stayed bridges (CSBs), are characterised by high flexibility which increases with the span of the bridge. This makes stay cables vulnerable to local vibrations which may have significant effects on the dynamic responses of long-span CSBs. Hence, it is essential to account for these effects in the assessment of the dynamics CSBs. In this paper, the dynamic responses of CSBs under vehicular loads are studied using the finite element method (FEM), while the local vibration of stay cables is analyzed using the substructure method. A case study of a cable-stayed steel bridge with a center span of 448 m demonstrates that stay cables undergo large displacements in the primary mode of the whole bridge although, in general, a cable’s local vibrations are not obvious. The road surface roughness has significant effects on the interaction force between the deck and vehicle but little effect on the global response of the bridge. Load impact factors of the main girder and tower are small, and the impact factors of the tension of cables are larger than those of the displacements of girders and towers. 相似文献
6.
为了研究高压架空输电线索结构与塔架等其他杆件连接处的滑移特性,定义了一组滑移索单元,由一个通过滑动节点连接的三节点活动滑移索单元和多个两节点非活动滑移索单元组成．基于更新拉格朗日格式推导了三节点直线型滑索单元几何非线性刚度矩阵,并通过两跨和三跨等高连续索结构的有限元数值算例验证了空间直线型滑移索单元的有效性．研究结果表明,推导的直线型滑移索单元张力与已有计算结果相比,误差在1％以内．考虑滑移的索结构初始平衡状态内力与不考虑滑移的情况比较相差较大,因而在实际工程中应该考虑索的滑移． 相似文献
7.
陈道齐 《福建工程学院学报》2012,(3):250-254
建立某型工程车辆驾驶室的结构有限元模型、空腔声学有限元模型。对驾驶室结构和室内空腔声场进行模态分析,得到结构振动特性和声学特性。计算分析驾驶室声-结构耦合模型在特定频率激励下的噪声分布情况,同时考虑吸声材料对驾驶员耳旁声压级值的影响,总结出在新车型开发阶段进行车内噪声预测和控制研究的有效方法。 相似文献
8.
INTRODUCTIONThetensegritystructurecomposedofcablesandbarsisoftwotypes.Oneistheflexibletensegritystructure.Thistypeofstructurehasnostiffnessandtheshapeofthestructureisnotde terminedwhennoprestressisapplied .Theform findingprocessfortheinitialequilibriumisa… 相似文献
9.
气垫导轨装置在碰撞实验中的改进 总被引：1，自引：0，他引：1
在气垫导轨上做碰撞实验,最大限度地减少了摩擦阻力的影响,但在实际的实验过程中,仍发现滑块的初速度不同时,粘滞性摩擦阻力对测量结果有不同程度的影响,为此在气垫导轨上增加了电子发射装置,较好地控制滑块的初速度和测量滑块的加速度,从而减小粘滞性摩擦阻力对测量结果的影响。 相似文献
10.
The nonlinear finite element method is used to analyze the geometrical nonlinear stability of cabletruss domes with different
cable distributions. The results indicate that the critical load increases evidently when cables, especially diagonal cables,
are distributed in the structure. The critical loads of the structure at different rise-span ratios are also discussed in
this paper. It was shown that the effect of the tensional cable is more evident at small rise-span ratio. The buckling of
the structure is characterized by a global collapse at small rise-span ratio; that the torsional buckling of the radial truss
occurs at big rise-span ratio; and that at proper rise-span ratio, the global collapse and the lateral buckling of the truss
occur nearly simultaneously.
Project (No. 50278086) supported by the National Natural Science Foundation of China 相似文献
11.
A double strut cable dome structural system was presented to improve the mechanical behaviour of a cable dome. This structure has good stability and is convenient to construct. To investigate its construction method and static performance, a structural model with a 6-m diameter was designed. From the nodal equilibrium equation, the calculation formulas for the prestress distribution with self-weight considered were deduced. Two types of construction methods, namely, assembling at high altitude and integral lifting, were adopted in the shape-forming process of the double strut cable dome, monitoring the internal force of the cable-strut components and the structural deformation. According to loading tests under full-span load and half-span load, the static behaviour of the structure was obtained and compared with the results from finite element analysis. Using the formulas deduced in this paper, the actual initial prestress considering self-weight for a double strut cable dome can be obtained accurately. This structure was suitable for tensioning the outer diagonal cables to apply prestress. Combined with the construction method for integral lifting, the difficulty and workload of the construction process can clearly be reduced, making the structure favourable for engineering application. Under an external load, the internal force of the ridge cables and inner diagonal cables decreases and the internal force of the other components increases. The results of the model tests were in good agreement with those of the finite element analysis. 相似文献
12.
The effects of symbolic modeling in the form of stories were examined in changing young children's sharing behavior and knowledge of sharing. Nursery school and kindergarten children who displayed a low frequency of sharing were assigned to experimental and control conditions. The experimental group heard stories and viewed slide tape shows of modeled sharing. The control group heard animal stories and viewed slide tape shows with no modeled sharing. The results were as follows: (a) The modeling group shared significantly more than the control group. (b) The modeling group increased their sharing across the three experimental days, and shared significantly more than the control group on both the second and third days. (c) The modeling group acquired significantly more knowledge about sharing. The findings provide strong evidence for the efficacy of models in both book and slide formats for young children. 相似文献
13.
ZHANG Xin-jun YING Lei-dong 《浙江大学学报(A卷英文版)》2007,8(5):693-698
To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable’s cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge, its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable’s cross-sectional area should be deter-mined by the principle of equivalent axial stiffness. 相似文献
14.
预应力钢结构微尺模型实验技术 总被引：2，自引：0，他引：2
为研究微尺模型中预应力拉索的相关实验技术,以竖向预应力钢结构体系中2个典型结构为对象进行了试验,主要阐述微尺试验模型的设计、预应力的施加与测定方法、外荷载的施加方法,并着重分析了这些方法的优缺点。结果表明,螺杆拧张法施加预应力能够较好地模拟拉索只受拉不受压的受力特点,但存在系统误差,与该法配套宜采用传感器测试拉索力;丝扣拧张法施加预应力相对比较精确,但不便于更换拉索,与该法配套宜采用应变片测试拉索力。 相似文献
15.
抗滑桩在边坡稳定分析中,主要是确定其合理长度和间排距,针对合理长度这个问题,基于有限元法研究了抗滑桩受力和周围土体变形情况,研究发现当桩长到达某一值后,抗滑桩的最大剪力趋于定值、最大弯矩趋于定值,且周边土体位移减小到某值也不再减小;由剪力、弯矩趋于定值和土体位移不再减小得到的抗滑桩长度基本上一致,此值即为采用有限元法得到的抗滑桩长度,并且与实际工程采用的抗滑桩长度对比发现两者长度基本相符. 相似文献
16.
17.
利用扫描探针显微镜考察了硅基材料的摩擦磨损性能,同时考虑了环境因素、循环扫描次数的影响;通过实验设计,得出了该材料表面的形貌,初步分析了其摩擦磨损性能。结果表明:压电陶瓷的滞后效应和非线性效应的影响比较显著;随着外界湿度的增加,湿度对材料表面黏附力和摩擦系数有较大的影响;外加载荷和扫描循环次数直接决定材料表面的耐磨性能。 相似文献
18.
Wrinkle analysis of a space planar film reflect-array 总被引：1，自引：0，他引：1
The presence of wrinkles in a membrane is the main factor that induces surface errors on space planar film reflectarrays. Based on the commercial finite element (FE) package ABAQUS, a numerical procedure for membrane wrinkle analysis was set up, and used to analyze a square planar film reflect-array under pure shear force to evaluate its induced wrinkle characteristics. First, the effect of shear force on the wrinkle pattern of the array was studied and validated by experiment. Second, the effect of prestress was studied. When the prestress increases, the quantity of the wrinkles increases, and the amplitude of the wrinkles decreases. Third, the influence of the boundary conditions was investigated. A frame side edge structure has a relatively smooth surface, but also relatively high stress. Finally, the behavior of a joint seam was analyzed. The results indicate that a joint band has a significant influence on the wrinkle pattern of the membrane. 相似文献
19.
焦君安 《杨凌职业技术学院学报》2012,(4):49-52
由于静摩擦力和滑动摩擦力在概念、存在条件和作用效果等方面都很相似,所以。通常人们都忽略了它们之间的差别,认为静摩擦力和滑动摩擦力是同一类力,把它们都归属为摩擦力,而实际上静摩擦力和滑动摩擦力是性质完全不同的两类力。本文从力学的基本原理出发,通过对静摩擦力和滑动摩擦力做功过程的理论分析和计算,给出静摩擦力和滑动摩擦力做功特点及做功过程能量转换差异,从而得出结论：静摩擦力和滑动摩擦力是两类性质不同的力,即静摩擦力是一种非耗散力而滑动摩擦力是一种耗散力。 相似文献
20.
Alternate path(AP) method is the most widely used method for the progressive collapse analysis,and its application in frame structures has been well proved.However,the application of AP method for other structures,especially for cable-stayed structures,should be further developed.The four analytical procedures,i.e.,linear static,nonlinear static,linear dynamic,and nonlinear dynamic were firstly improved by taking into account the initial state.Then a cable-stayed structure was studied using the four improved methods.Furthermore,the losses of both one cable and two cables were discussed.The results show that for static and dynamic analyses of the cable-stayed bridges,there is large difference between the results obtained from simulations starting with either a deformed or a nondeformed configuration at the time of cable loss.The static results are conservative in the vicinity of the ruptured cable,but the dynamic effect of the cable loss in the area farther away from the loss-cable cannot be considered.Moreover,the dynamic amplification factor of 2.0 is found to be a good estimate for static analysis procedures,since linear static and linear dynamic procedures yield approximately the same maximum vertical deflection.The results of the comprehensive evaluation of the cable failure show that the tread of the progressive failure of the cable-stayed bridges decreases when the location of the failed cables is closer to the pylon. 相似文献