圆形截面灌注桩正截面均匀配筋计算可视化     

杨超  罗运军  张英才 《岩土工程技术》2004,18(6):299-302

在圆形截面均匀配筋偏心受压混凝土构件的正截面承载力基本计算公式的基础之上 ,结合基坑工程中圆截面灌注桩的受力特点 ,推导了灌注桩均匀配筋计算的有关公式 ,并以此为基础 ,利用可视化编程软件Delphi 6 .0编写了相应的配筋计算程序。通过实际例证 ,表明该程序计算快捷且结果准确。  相似文献   

长螺旋钻机成孔压灌砼桩后插钢筋笼施工工艺及配套装置的应用     

杨永霞  高谦 《岩土工程技术》2004,18(6):279-281

结合某一工程实例 ,探讨钻孔灌注桩先成桩后插钢筋笼法的施工工艺以及配套装置的工作原理、性能特点、适用范围和施工方法  相似文献   

Seismic performance evaluation of steel arch bridges against major earthquakes. Part 1: dynamic analysis approach     

Tsutomu Usami  Zhihao Lu  Hanbin Ge  Takeshi Kono 《地震工程与结构动力学》2004,33(14):1337-1354

In this study the inelastic behavior of steel arch bridges subjected to strong ground motions from major earthquakes is investigated by dynamic analyses of a typical steel arch bridge using a three‐dimensional (3D) analytical model, since checking seismic performance against severe earthquakes is not usually performed when designing such kinds of bridge. The bridge considered is an upper‐deck steel arch bridge having a reinforced concrete (RC) deck, steel I‐section girders and steel arch ribs. The input ground motions are accelerograms which are modified ground motions based on the records from the 1995 Hyogoken‐Nanbu earthquake. Both the longitudinal and transverse dynamic characteristics of the bridge are studied by investigation of time‐history responses of the main parameters. It is found that seismic responses are small when subjected to the longitudinal excitation, but significantly large under the transverse ground motion due to plasticization formed in some segments such as arch rib ends and side pier bases where axial force levels are very high. Finally, a seismic performance evaluation method based on the response strain index is proposed for such steel bridge structures. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

线阵推扫影像的核线模型研究   总被引：2，自引：0，他引：2  

巩丹超  张永生  邓雪清 《遥感学报》2004,8(2):97-101

通过对线阵CCD推扫式影像和框幅式中心投影影像的核线理论的对比研究，建立了线阵CCD推扫式影像的核线理论，并探讨了它的基本特性，从而为核线在线阵CCD推扫式影像中的应用提供了理论基础。  相似文献   

Place‐based action in Wollongong: the role of union–community alliances in constructing labour geographies of steel     

Liza Tonkin 《The Australian geographer》2004,35(1):59-75

Place‐based action (PBA) features prominently in labour geographies, particularly in restructuring politics, and is consistently employed as an enduring union tactic, yet it remains relatively undervalued in steel restructuring accounts, with common approaches emphasising the class instability and limitations of such action. In contrast, and to redress the apparent imbalance, this paper argues the merit of recognising PBA as a distinct movement‐based politic with specific forms of representation and empowerment. Such an approach should lead to greater recognition and appreciation of the impact that PBA has had historically. To illustrate this, a case study is presented of how local groups used place‐based action in Wollongong to shape steel restructuring politics and industry policy during the 1980s. Although powerful, the influence of PBA diminished at the policy writing stage. Rather than devaluing all benefits from PBA due to such limitations, it is suggested that the constraints on PBA at this point suggests the need for other forms of intervention. It is concluded that the approach suggested here highlights when other tactics are required, strengthening real‐world tactical analysis.  相似文献   

The GGOS as the backbone for global observing and local monitoring: A user driven perspective   总被引：1，自引：0，他引：1  

H.-P. Plag   《Journal of Geodynamics》2005,40(4-5):479

A key geodetic contribution to both the three Global Observing Systems and initiatives like the European Global Monitoring for Environment and Security is an accurate, long-term stable, and easily accessible reference frame as the backbone. Many emerging scientific as well as non-scientific high-accuracy applications require access to an unique, technique-independent reference frame decontaminated for short-term fluctuations due to global Earth system processes. Such a reference frame can only be maintained and made available through an observing system such as the Global Geodetic Observing System (GGOS), which is currently implemented and expected to provide sufficient information on changes in the Earth figure, its rotation and its gravity field. Based on a number of examples from monitoring of infrastructure, point positioning, maintenance of national references frames to global changes studies, likely future accuracy requirements for a global terrestrial reference frame are set up as function of time scales. Expected accuracy requirements for a large range of high-accuracy applications are less than 5 mm for diurnal and sub-diurnal time scales, 2–3 mm on monthly to seasonal time scales, better than 1 mm/year on decadal to 50 years time scales. Based on these requirements, specifications for a geodetic observing system meeting the accuracy requirements can be derived.  相似文献   

A comparative study of concentrated plasticity models in dynamic analysis of building structures     

Maurice A. Dides  Juan C. de la Llera 《地震工程与结构动力学》2005,34(8):1005-1026

Concentrated plasticity (CP) models are frequently used in static and dynamic building analysis and have been implemented in available commercial software. This investigation deals with three different CP‐models, a simplified macroelement model (SEM) for a complete building story, a frame element with elasto‐plastic interaction hinges (PH), and a frame element with fiber hinges (FB). The objectives of this work are to evaluate the quality of the earthquake responses predicted by these models and to identify important aspects of their implementation and limitations for their use in dynamic analysis. The three elements are tested in a single‐story asymmetric plan building and in a three‐story steel building. Results show that base shear and global response values are usually computed with better accuracy than interstory deformations and local responses. Besides, the main limitation of elasto‐plastic CP models is to control the displacement offsets that result from perfect elasto‐plastic behavior. On the other hand, calibration of the SEM‐model shows that global responses in steel structures may be computed within 20% error in the mean at a computational cost two orders of magnitude smaller than that of the other CP elements considered. However, the three element models considered lead to increasing levels of accuracy in the dynamic response and their use depends on the refinement of the analysis performed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Pseudo‐dynamic seismic response of reinforced concrete frames infilled with non‐structural brick masonry     

F. Colangelo 《地震工程与结构动力学》2005,34(10):1219-1241

This paper presents pseudo‐dynamic test results on the in‐plane seismic behaviour of infilled frames. Thirteen single‐storey, single‐bay, half‐size‐scale, reinforced concrete‐frame specimens, most of which infilled with non‐structural masonry made of perforated bricks and cement mortar are tested. The infills are in contact with frames, without any connector; openings are not covered. The frames are different in their strength and details, reinforcement grade, and aspect ratio. Seismic input is the 1976 Tolmezzo (Friuli, Italy) ground acceleration, to which specimens are subjected two times: virgin and damaged by the previous test. The global seismic response of initially virgin infilled specimens considerably differs from that of bare specimens. This follows a dramatic change of properties: compared to a bare frame, the initial stiffness increases by one order of magnitude, and the peak strength more than doubles. The peak drift lessens; however, the displacement ductility demand does not. The energy demand is greater. Nevertheless, the influence of infill decreases as damage proceeds. Displacement time histories of damaged specimens are quite similar. At the local level, infill causes asymmetry and concentration of the frame deformation. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

洛阳热电厂汽机主厂房2、3号机房爆破拆除技术          下载免费PDF全文

袁长征  张锦灵 《探矿工程》2005,32(7):58-60

绍了采用控制爆破拆除大跨度工业厂房的施工方法，主要论述了在要求振动较小情况下，怎样控制爆破参数。  相似文献   

Critical Top Tension for Static Equilibrium Configuration of A Steel Catenary Riser     

Chainarong ATHISAKUL  Karun KLAYCHAM  Somchai CHUCHEEPSAKUL 《中国海洋工程》2014,(6):829-842

This paper aims to present the critical top tension for static equilibrium configurations of a steel catenary riser（SCR） by using the finite element method. The critical top tension is the minimum top tension that can maintain the equilibrium of the SCR. If the top tension is smaller than the critical value, the equilibrium of the SCR does not exist. If the top tension is larger than the critical value, there are two possible equilibrium configurations. These two configurations exhibit the nonlinear large displacement. The configuration with the smaller displacement is stable, while the one with larger displacement is unstable. The numerical results show that the increases in the riser＇s vertical distances, horizontal offsets, riser＇s weights, internal flow velocities, and current velocities increase the critical top tensions of the SCR. In addition, the parametric studies are also performed in order to investigate the limit states for the analysis and design of the SCR.  相似文献