基于PSD的细长杆直线度测量技术研究

细长杆直线度是大型机械零部件测量中的一项关键技术,是提升大型机械性能和质量的必要手段。为提高细长杆直线度测量水平,克服现有方法的局限性,提出一种基于P S D的光学式细长杆直线度测量方法。根据细长杆结构特点,给出测量原理与测量系统总体方案,建立直线度测量数学模型。以某工程机械核心零部件为例,采用所设计测量装置与激光跟踪仪进行测量与比较,证明所设计测量装置测量误差小于0.01 mm。测量系统分析结果表明,所设计测量装置的合计量具RR占研究变异的百分比小于10%,说明其重复性与再现性良好,进一步证明其可以应用于实际生产现场。本研究为大型机械细长杆直线度等关键几何误差测量提供了技术支持。     

对中杆倾斜误差的简易消除法

本文提出了比传统校正法易于操作的悬高垂球校正法 ,论证了采用特殊的测量方法来消除对中杆倾斜误差的对中杆旋转 180°测量法 ,这两种方法具有简单易于操作的优点 ,便于提高施工测量精度     

细长压杆稳定分析的对称性方法

利用系统构型和载荷的对称性对分析模型进行简化是力学建模的重要环节,针对细长压杆稳定性的高阶模态分析问题,采用对称性方法,分析两端铰支和两端固定细长压杆的屈曲模态和特征值表达式,建立了对称压杆与非对称压杆屈曲载荷之间的联系,比较了压杆稳定性分析中四阶和二阶微分方程方法的特征,计算实例证明提出的方法有效。     

烟囱、水塔砌筑用木引尺的改进

烟囱、水塔砌筑所用的木引尺,使用时侧向稳定性差,摆动大,挠度也大,对中比较困难。标尺杆与架杆之间有高度差(木架杆一般高160mm 左右),在每次测量校正时都存在比较大的偏差。既影响施工质量,也给施工人员操作带来一定的难度。我们在施工30m 高砖砌水塔过程中,将木引尺改制成钢木引尺,即将木引尺架改为     

超大型瓷套切割研磨芯杆的研究与应用

介绍了超大型瓷套端面切割、研磨芯杆的设计及使用方法。通过对不同切割、研磨工艺结构和种类的优缺点比较,结合超大型瓷套的结构特点及切割、研磨方法,确定了新结构的切割、研磨芯杆。该芯杆增加了延伸杆、保护套和辅助支撑,在实际应用中,能够满足制造工艺要求。加工出的产品满足产品技术要求,解决了超大型瓷套产品制造技术中的断面切割研磨难题。     

目标偏心误差与竖盘指标差对放样的影响分析

虽然3S技术已经广泛应用于测绘领域,但是基于全站仪的传统测量仍然有着不可替代的作用[1]。在利用全站仪放样时,其精放样阶段以水平角测量与距离测量两部分操作为主。通过分析对中杆偏心误差和竖盘指标差对水平角测量与距离测量的影响,定量地描述了其规律,对放样过程中的超差现象进一步做出合理的解释分析,提出高效的处理方法,对放样工作具有一定的指导意义。     

钎探工具的改进

《建筑工人》1997年第3期刊登的《现场制作钎探工具》一文,对我们启发很大。经过我们实践应用,证明这种钎探工具比较适用。但我们在施工过程中,觉得按照文中所述利用穿钢筋的方法拔钎杆比较费力,见图1。利用杠杆原理,我们在施工中改变了原来的拔钎杆方法,见图2。一个人用φ50钢管(工地上的架杆)作撬杠,重复向下压,铁板就卡住钎杆,使钎杆逐渐上移,直至把钎杆拔出来。垫块可以选用工地上的砖、石     

新型深层螺旋板载荷试验装置研究及成果应用

常规螺旋板载荷试验过程中,随着测试深度增加,传力杆的弯曲变形逐渐累积,沉降测量的误差逐渐增大,测试精度逐渐降低,且该误差难以避免和修正,导致对地基土综合性状判别误差较大,不能满足设计要求。本文成功研制了集成位移测量和载荷测量的新型螺旋板载荷试验探头,利用内轴和套管相对位移原理,将传统的地表测量沉降位移方式改进为在地下的螺旋板头上端直接测量方式,消除了传力杆弯曲变形和地表扰动对试验结果的影响,使测试深度和精度取得了突破性进展。     

即时三维测量技术在网架施工中的应用

钢网架一般采用地面拼装后再吊装的施工方法,大连开发区文化中心A区图书馆屋盖网架,因场地工期等原因,采用高空散拼法施工,这对测量定位要求更高,介绍了用即时三维测量技术定位网架节点的施工工艺,既满足了网架中球和杆的定位误差,又保证了工期。     

基于应变差值类影响线的桁架损伤识别

面向基于静力测试数据的结构损伤识别问题,发展一种基于应变差值类影响线来识别损伤的方法,该方法利用事先规定应变测量单元的桥梁结构在单位移动荷载作用下的应变影响线,通过差值、求导计算,提出以应变差值、一阶导和二阶导影响线作为损伤指标的损伤诊断方法,一点测量多点激励,直接对所得影响线图进行观察即可准确定位损伤。本文分别以钢桁梁桥和星海跨海悬索大桥主桁架简化模型为例,分析了距离损伤杆远近不同的腹杆做测点识别损伤的效果,结果表明:该方法可以有效识别桁架腹杆损伤。     

Experimental studies on the mechanical properties and deformation & failure mechanism of U-type confined concrete arch centering

To solve the support problems of high stress roadways in deep mines, we developed a new 3D U-type confined concrete support system from the conventional U-type steel arch centering. Its core is the U-type confined concrete (UCC) arch centering. With a real scale mechanical test system for the confined concrete arch centering in underground engineering and numerical calculation methods, we studied in depth on the mechanical properties and deformation & failure mechanism of UCC arch centering (UCCAC). The results of the study show the yielding load and the limit load of UCC29 arch centering is 1230 kN and 1310 kN respectively in even pressure loading conditions; and a slight difference between the laboratory test and the numerical simulation on these two is 8.86% and 12.5% respectively. The deformation form of the arch centering is “vault uplifting, legs introverting and the overall shape becomes oval”; and the largest deformation occurs between the middle of the legs and the arch centering springing. The deformation and failure mechanism of arch centering is the partial strength failure causes the entire arch centering to lose its stability. The application on site shows the UCCAC has a superb effect on the surrounding rock control; therefore, the UCCAC is a new effective support for the high stress roadways in deep mines.     

Seismic response of self‐centering precast concrete frames with hysteretic dampers

With the rapid development of cities and the invasion of major natural disasters such as earthquakes, the resilience city as a new design concept has been paid more and more attention. As an important branch of self‐centering seismic resisting system, self‐centering concrete frame system has been studied by many scholars. These studies prove that self‐centering concrete frame structure has excellent self‐centering ability but poor energy dissipation capacity. Adhering to the working principle of self‐centering structure and considering the development concepts of building industrialization and modularization, this paper proposed a kind of self‐centering precast concrete frame with hysteretic damper (SCPCHD). In order to verify its energy dissipation capacity and seismic performance, elaborate finite element models were established and elastoplastic dynamic time history analyses were carried out. The results showed that the SCPCHD frame has a similar interstory displacement response to the reinforced concrete (RC) frame and the energy dissipation performance of its joint is obviously superior to the RC frame under rare earthquake because the SCPCHD frame has low damage characteristics and excellent damping device. In summary, this paper proves the feasibility and superiority of the SCPCHD frame, providing reliable support for further research.     

Experimental study on a self‐centering coupling beam eliminating the beam elongation effect

Traditional self‐centering coupling beams display a beam elongation effect under large shear deformation. The beam elongation effect conflicts with the rigid slab assumption and may induce harmful compressive stress between the coupling beam and the walls. This paper proposes a novel self‐centering coupling beam, aimed at eliminating the beam elongation effect. The proposed self‐centering coupling beam consists of two connecting parts and one central rocking part. The main feature of the self‐centering coupling beam is the gap between the central rocking part and the one connecting part. This gap provides sufficient space for the beam elongation effect. Friction dampers are installed at the corners of the coupling beam to provide energy dissipation capacity. An experimental study, including three specimens, was carried out. The test results demonstrate the satisfactory self‐centering and energy dissipation capacities of the novel coupling beam. Based on these test results, we quantitatively discuss the pretension force in the pretensioning strands, the friction force of the damper and the gap width in the coupling beam. A finite element analysis is performed, showing that the coupling beam gap protects the coupling beam and adjacent shear wall from damage caused by the beam elongation effect. Copyright © 2015 John Wiley & Sons, Ltd.     

大跨度拱桥施工拱架的设计方案研究

贵州底那河大桥是一座跨径120m的上承式拱桥,采用常备式钢桁拱架法现浇施工,该拱架是贵州省跨度最大的悬拼拱架。以底那河大桥为工程背景,介绍了常备式钢桁拱架在现浇拱桥施工中的应用,通过拱架施工过程中承载力的计算和整体稳定性计算,对施工方案进行了验算和优化研究,对于此类桥梁施工方案的设计和计算具有一定的借鉴意义和工程实用价值。     

信息化测绘的时代背景与社会形态

测绘是国民经济和社会发展的重要基础性工作,信息化测绘是可持续发展、测绘事业发展和时代发展的需要。信息化测绘是在数字化测绘的技术基础上、在完全网络化运行环境下、能够实时有效地向信息化社会提供地理信息综合服务的现代测绘方式和功能形态。信息化测绘促使测绘行业的技术水平、产品内容和服务领域有了飞跃发展,有力推动了测绘行业向现代地理信息产业的转型,产品结构更加完善,服务方式更加开放,社会经济价值更加显现。     

铁路航测生产的现状浅析

介绍了铁路航测生产的现状及铁路航测生产流程,阐述了铁路航测相关产品和从业人员状况,并对铁路航测生产进行了展望,以积累丰富的航测经验,为铁路勘测设计提供更好的技术支持和服务。     

免棱镜全站仪在日照分析测量中的应用

简述了免棱镜测量与对边测量的原理。提出了利用免棱镜全站仪的对边测量功能在建筑物测量中的应用。从准备、建筑角点检查、建筑立面测量和建筑屋顶测量等方面介绍了测量的步骤。     

某拱架整体稳定性有限元分析

针对某桥的拱架拼装及主拱施工过程中的整体稳定性进行有限元分析,选择施工中5个工况进行拱架整体稳定性计算,分析了这些工况的失稳模态,指出了拱架失稳的原因,为确保拱桥施工的拱架稳定性要求提供了参考依据。     

Study of a new type of self‐centering beam‐column joint in steel frame structures

A new type of self‐centering beam‐column joint with installed steel arc plates is proposed in this study. First, mechanical behavior of the self‐centering joint using prestressed steel strands to provide the centering force is theoretically analyzed in detail, followed by experimental validation. New joints with different arc plate parameters are designed and tested under cyclic loading. Test results show that the hysteretic curve of the new joint exhibits typical characteristic of self‐centering capacity. By parametric analysis of five design parameters of the arc plate, it is found that vector height has the greatest influence on the joint's moment‐rotation skeleton curve, which is consistent with experimental findings. A simplified model of the joint is built in OpenSees to simulate its hysteretic behavior, which agrees well with the tested results. To demonstrate the effectiveness of the new joint to improve the seismic performance of the overall structure, a series of nonlinear time history analysis on a steel frame structure with the new joint under earthquakes are conducted, which show that the joint is particularly effective in reducing the residual interstory drift response.     

超长、超宽建筑物施工测量整体控制技术

国家会议中心工程超长,超宽,施工周期较长,测量精度标准要求高,常规测量手段难以满足要求。在施工现场布设两级控制网的测量方案,使建筑物的整体精度得到保障。超长轴线的投测采用独特的两点间恢复直线的测量方法,既满足施测精度,又提高测量效率。建筑物轴线竖向传递采用首层布设内控点,使用激光铅直仪进行传递的方法,满足细部轴线的测设精度。