注采剖面测试仪器的刚性柔性短接设计及应用

为了实现过环空测试仪器串顺利下井,基于两圆外切的原理设计制作刚性柔性短接连接各测试短节,变相缩短小直径过环空测试仪器串长度,降低产出剖面过环空测井的遇阻率。现场应用结果表明,刚性柔性短接配合小直径测井仪,使产出剖面过环空测试的遇阻率由65%降低到35%。因此,刚性柔性短接解决了由于井斜和环形空间小仪器串过长下入比较困难的问题,突破传统螺纹硬连接和橡胶软连接,刚性柔性短既是刚性的也是柔性的。但刚性柔性短接不能解决环套空间结蜡、死油和环套工具及变形造成的遇阻。

产出剖面测试仪器的刚性柔性短接设计及应用

为了实现过环空测试仪器串顺利下井,基于两圆外切的原理设计制作刚性柔性短接连接各测试短节,变相缩短小直径过环空测试仪器串长度,降低产出剖面过环空测井的遇阻率。现场应用结果表明,刚性柔性短接配合小直径测井仪,使产出剖面过环空测试的遇阻率由65%降低到35%。因此,刚性柔性短接解决了由于井斜和环形空间小仪器串过长下入比较困难的问题,突破传统螺纹硬连接和橡胶软连接,刚性柔性短既是刚性的也是柔性的。但刚性柔性短接不能解决环套空间结蜡、死油和环套工具及变形造成的遇阻。

钢框架结构半刚性连接节点失效模式控制的设计优化研究

以山东省某市QP2007-18号宗地项目为例,运用数值模拟方法,研究半刚性节点的失效模式,并对节点的梁柱结构进行设计优化。结果表明,设计的外伸端板半刚性连接节点的破坏形式为延性破坏,破坏时节点的端板先屈服,高强螺栓最后达到极限抗拉强度;增加钢梁和钢柱的刚度均可提高半刚性连接节点刚度,而提高钢梁的刚度则可增加半刚性连接节点的弯矩屈服荷载。

考虑衬砌板跨度影响的U型渠道热-力耦合研究

为了研究混凝土衬砌板纵向跨度对冻胀效应的影响,基于整体式小型U型渠道的结构特点和冻胀特征,视衬砌板和受冻基土为平面应变和三维实体结构,采用热-力耦合分析方法,分析研究了整体式小型U型渠道在冻胀作用下的效应。结果表明:1按三维实体分析的位移略小于按平面问题分析;2板与板刚性接缝处产生较大的不均匀纵向位移,是渠道受冻胀作用的薄弱位置;3板跨度越大,其纵、横向水平位移及竖向位移均略有增大。

预应力混凝土连续梁桥合拢段施工工艺的实施和研究

文章通过介绍滁河大桥主桥预应力合拢段施工工艺,阐述了预应力混凝土连续梁的合拢段施工中应加以注意的临时固结措施、体系转换和预应力施工等的施工工艺,并对其理论依据作了简要分析。

机场高填土地基工后不均匀沉降指标研究

以威斯特卡德板中受荷计算刚性道面PCN值的理论为基础,考虑刚性道面接缝传荷能力和山区机场地基不均匀沉降,建立了基于"地基-道面-飞机荷载"相互作用的足尺9块板道面结构三维有限元分析模型。运用该方法,根据统计的国内主要民航运输飞机ACN值,确立了15组计算分析模型。经威斯特卡德理论和Bisar软件验证了模型的可行性。研究表明,高填土机场道面板底最大拉应力与地基不均匀沉降呈线性关系,高填土机场工程中对于1‰的地基不均匀沉降控制比较合理,对于设计强度为5.0MPa以上的道面结构,允许地基最大不均匀沉降值为1.2‰。

后浇带的结构与施工

对后浇带的结构特点及其施工方法做了阐述,提出了施工中应注意的问题.

预制地连墙结构在海河护岸工程中的应用

简明介绍了预制地连墙结构在海河护岸工程设计、施工中的应用 ,并对工程效果进行评价。为城市市区高密度建筑群中的河道。

后浇带在部分商住楼中的作用

本文论述了后浇带在商住楼中的作用及优点,介绍了后浇带的适用范围。重点叙述后浇带的三种设置形式及关键环节的施工方法和注意事项。

膨胀元件的使用及其常见问题分析

地铁刚性接触网系统中,膨胀元件的使用保证了高速区段列车受电弓在接触网两不同锚段间机械上和电气上平稳过渡,但由于高速区段弓网关系较为复杂,膨胀元件在运营中还是存在较多的问题。本文根据膨胀元件在广州地铁三号线北延段刚性接触网系统中的使用情况,对膨胀元件在使用中出现的不良技术状态进行了分析并根据现场维护经验总结了膨胀元件不良技术状态的调整方法以及日常的维护措施。

建筑施工中后浇带施工技术

后浇带是在现浇整体钢筋混凝土结构中，施工期间保留的为防止因温度、收缩沉降生成的变形缝，其在施工期间保留一定时间而将结构暂时划分为若干部分，在经过结构内部收缩后再浇捣高一级混凝土以成为连续整体，其属于一种刚性接缝，适用于不宜设置柔性变形缝或后期变形趋于稳定的结构。该部位施工易在气温较低时段浇筑较构件混凝土强度高一级的混凝土或掺加微量铝粉的混凝土，以防止后期该部位开裂。后浇带可分为后浇沉降带、后浇收缩带和后浇温度带，其作用是分别解决高层建筑内主楼与底层裙房间的差异沉降、钢筋混凝土的收缩变形及减小温度应力等，并且一种可具备多种变形缝功能，

Development of Chinese large-scale space end-effector

In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.

Effect of heating time on bonding interface, atom diffusion and mechanical properties of dissimilar titanium joints produced by thermal self-compressing bonding

Solid-state bonding between pure titanium and Ti6Al4V(TC4)alloy was conducted by a new bonding method named as rigid restraint thermal self-compressing bonding.Effects of heating time on bonding interface,atom diffusion and mechanical properties of the joints were studied.Results show that atom diffusion between pure titanium and TC4 alloy significantly takes place during bonding.The diffusion depths of Al and V in pure titanium side are increased with increasing heating time.Due to the enhancement of atom diffusion,bond quality of the bonding interface is improved along with the increase of heating time.The heating time seems to have little effect on microhardness distribution across the joint.However,the tensile strength and ductility of the joint have close relation to heating time.Prolonging heating time can improve the tensile strength and ductility of the joint,especially the latter.When the heating time increases to 450 s,solid-state joint with good combination of strength and ductility is attained.

Effects of temperature change on elastic behavior of steel beams with semi-rigid connections

Based on the nonlinear displacement-strain relationship,the virtual work principle method was used to establish the nonlinear equilibrium equations of steel beams with semi-rigid connections under vertical uniform loads and temperature change.Considering the non-uniform temperature distribution across the thickness of beams,the formulas for stresses and vertical displacements were presented.On the basis of a flowchart for analysis of the numerical example,the effect of temperature change on the elastic behavior of steel beams was investigated.It is found that the maximal stress is mainly influenced by axial temperature change,and the maximal vertical displacement is principally affected by temperature gradients.And the effect of temperature gradients on the maximal vertical displacement decreases with the increase of rotational stiffness of joints.Both the maximal stress and vertical displacement decrease with the increase of rotational stiffness of joints.It can be concluded that the effects of temperature changes and rotational stiffness of joints on the elastic behavior of steel beams are significant.However,the influence of rotational stiffness becomes smaller when the rotational stiffness is larger.

Sensitivity Analysis and Optimization of Geometric Parameters of a New Fluid Bag Buffer Mechanism on Buffering Performance

A new fluid bag buffer mechanism,which can provide large axial stiffness under the small displacement,is designed.The dynamic change laws of the mechanism stiffness and the internal pressure of the fluid bag are studied when it is subjected to impact load.According to the protection performance for the flexible joint and the pressure change in the fluid bag during the impact process,the sensitivity of the geometric parameters of the fluid bag to the axial stiffness is analyzed by using the orthogonal experimental method,and the optimal parameter combination of the geometric parameters of the fluid bag under impact is obtained,leading to the displacement of the inner shell reduce by 41.4%.The results show that the internal pressure of the fluid bag is a rising process of oscillation and fluctuation.The sensitivity of the geometric parameters of the fluid bag to the displacement of the inner shell from high to low is as follows:Height H,radius r,wall thickness t,chamfer A.The correlation between the geometric parameters of the fluid bag and its internal pressure is:H is negatively correlated with the internal pressure,while the r,t,and A are positively correlated with the internal pressure.

Moment-Rotation Characteristics for Flexible Beam-to-Column Steel Joint Exposed to Fire

Analytical models used to describe behaviour of steel frame loadbearing structures in fully developed fire usually do not allow for reduced joint stiffness due to increased member temperature. Joints previously designed as nominally rigid tend to become flexible in fire situation, with degree of flexibility increasing during fire development. Reliable analysis of this phenomenon and its influence on the redistribution of internal forces result in the need for developing appropriate characteristics, describing relationship between bending moment applied to the joint and joint rotation. Characteristics of such type, specified for fire conditions, depend on steel temperature, in the current work, the authors propose a practical approach to develop such characteristics, based on the knowledge of analogous characteristic prepared for persistent design situation. The developed technique does not require to generalize the classical component method to the case of fire, which may be difficult in practical situations. The proposed computational algorithm has been tested on an example of a typical beam-to-column joint.

Design of the Composite Steel-Glass Beams with Semi-Rigid Polymer Adhesive Joint

New and high transparent structural element, steel-glass composite beam was developed in respect to fabrication, static-structural and architectural criteria and consists of steel flanges and glass web assembled together by semi-rigid polymer adhesive, which is the key element of whole composite system. These beams can be used mainly as members of high transparent roof or floor structure as well as stiffening fins for large area glass facades. This paper deals with experimental research performed at CTU （Czech Technical University） Prague, which started by adhesive selection and initial material tests by ISO527, continued via small-scale steel-glass connection tests and graduated by full-scale tests of hybrid beams with the span of 4 m. Generalized results of these experiments, analytical and numerical studies serve as device, how to accurately predict the behavior of the beam, describe the stress distribution along the cross section and safely and economically design such a kind of structure with semi-rigid shear connection, made by polymer adhesive.

Progressive Collapse Analysis of Concrete-Filled Steel Tubular Frames with Semi-rigid Connections

A 9-story concrete-filled steel tubular frame model is used to analyze the response of joints due to sudden column loss. Three different models are developed and compared to study the efficiency and feasibility of simulation, which include substructure model, beam element model and solid element model. The comparison results show that the substructure model has a satisfying capability, calculation efficiency and accuracy to predict the concerned joints as well as the overall framework. Based on the substructure model and a kind of semi-rigid connection for concretefilled square hollow section steel column proposed in this paper, the nonlinear dynamic analyses are conducted by the alternate path method. It is found that the removal of the ground inner column brings high-level joint moments and comparatively low-level axial tension forces. The initial stiffness and transmitted ultimate moment of the semi-rigid connection are the main factors that influence the frame behavior, and their lower limit should be guaranteed to resist collapse. Reduced ultimate moment results in drastic displacement and axial force development, which may bring progressive collapse. The higher initial stiffness ensures that the structure has a stronger capacity to resist progressive collapse.

Effect of Suppressed DOF on a Rigid RC Bridge Response under Strong Earthquake Motion

NLTHA （nonlinear time history analysis） is impractical for widespread used by the professional engineer because it requires long and inefficient computational time involving complexities when six DOF （degree of freedom） per node is applied. The NLTHA nowadays is predicted by MPA （modal pushover analysis）. In this method, effects of higher modes on the dynamic response are considered to estimate seismic demands for structures. In this study, the effect of the reduction of number of DOF is analyzed using 3D NLTHA together with MPA of a rigid connection RC bridge under large earthquake motion. The results are compared with the 6 DOF NLTHA in terms of response of the structure and CPU time to obtain the most efficient computational effort. Result of NLTHA showed that the computational time of the structure both for 4 DOF （without two lateral torsional effects） and 3 DOF （without two lateral torsional and vertical displacements） was reduced significantly compared to the structure using 6 DOF. The reduction of computational time was close to fifty percent both for 4 and 3 DOF＇s. When the maximum responses between NLTHA and MPA are compared, it is found that the differences are insignificant.

Research on BP-ANN Model of Semi-rigid Connection

The beam-to-column semirigid connection in a steel frame structure is represented by a zero-length rotational spring at the end of the beam element. The beam-to-column semirigid connection behavior is represented by its moment-rotation relationship. Several traditional mathematical models have been proposed to fit the moment-rotation curves from the experimental database,but they may be more reliable within certain ranges. In this paper, the intellectualized analytical model is proposed in the semirigid connections for top and seat angles with double web angles using the feed-forward back-propagation artificial neural network （BP-ANN） technique. the intellectualized analytical model from experimental results based on BP-ANN is more reliable and it is a better choice to the moment-rotation curves for beam-to-column semirigid connection. The results are found to provide effectiveness to the experimental response that is satisfactory for use in steel structural engineering design.