Fragility and risk assessment of freestanding building contents

Multistorey buildings often have a valuable inventory consisting of objects that their possible damage during an earthquake will cause unacceptable losses. The paper presents a novel, fully performance-based seismic reliability and risk assessment framework for freestanding structural components and contents that can be modelled as rocking rigid blocks. The seismic response of building contents depends on several parameters such as the geometry of the object, the dynamic characteristics of the building and the storey that the object is located. The demand at the storey level is first obtained, and then the response of the contents is calculated using the storey acceleration response history. The demand of the structure is obtained with the aid of a modified version of the Incremental Dynamic Analysis method and subsequently the fragility curves of the rocking building contents are derived for every storey of interest. Different options for fragility assessment are discussed, and the underlying details of the problem are investigated. A simplified approach, where the fragility of the freestanding components and the structure are derived separately, is also presented. The method combines existing fragility curves and thus is suitable for quickly assessing the reliability of a building's inventory, offering sufficient risk estimates.     

大跨度钢桁架转换结构振动台试验研究

以某带高位大跨钢桁架转换结构高层建筑为工程背景,进行了1/25缩尺比例的模型振动台试验,通过粘贴在钢桁架杆件上的应变片,测试了输入不同加速度峰值地震波作用下钢桁架的地震响应。在加速度峰值0.9g地震波作用下,两端支承钢桁架筒体剪力墙才出现裂缝,表明连接部位剪力墙受力性能较好;人工波作用下结构的地震响应最大,层地震作用力在钢桁架转换结构层有突变;试验中随模型结构裂缝发展和抗侧刚度衰减,层地震作用力分布发生变化,其中钢桁架转换结构层承担地震力相对减小,钢桁架应变反应也相对趋缓;钢桁架两端杆件受力较大,表明支承剪力墙对钢桁架的约束作用较大。     

地下贯通工程测量方案的优化理论和方法

地下贯通工程的控制测量导线多为加测陀累方位角的导线，本文讨论了贯通工程导线加测陀螺边的个数，位置，以及提高其可靠性，经济性的有关问题。     

小口径钢管桩与固结灌浆技术联合应用于岩溶地基处理

以工程实践为例,简述复杂岩溶地基处理中小口径钢管桩与固结灌浆技术联合应用的设计、施工工艺及应用效果。     

Potential of the VLTI for linking stellar frames to ICRF

The question of positioning the optical counterparts of the ICRF quasars is outlined in the perspective of future space astrometry missions, which ultimately will bring a new realization of the ICRS in the optical range. Ground-based interferometry with a dual-field observing mode (PRIMA/VLTI),together with the missions DIVA and FAME, will have a key role in building an extragalactic reference frame in the optical/near-IR range with about the same accuracy as that of the present (VLBI) primary frame. This revised version was published online in July 2006 with corrections to the Cover Date.     

带有小数补偿的低频数控振荡器及其基于FPGA的实现

在分析数控振荡器（NCO）工作原理的基础上,以低频信号为例,研究了影响NCO性能的几个因素。结合杂散特性,着重讨论了频率控制字误差对输出频率带来的影响,提出在相位累加器中加入小数部分补偿,以使降低信号频率门限值和提高输出的准确性。最后采用FPGA（现场可编程门阵列）实现了带有小数补偿的NCO,在兼顾硬件资源的同时优化了系统性能,另外通过仿真验证了这种方法的可行性。     

Seismic analysis of diagrid structural frames with shear-link fuse devices

This paper presents a new concept for enhancing the seismic ductility and damping capacity of diagrid structural frames by using shear-link fuse devices and its seismic performance is assessed through nonlinear static and dynamic analysis.The architectural elegancy of the diagrid structure attributed to its triangular leaning member configuration and high structural redundancy make this system a desirable choice for tall building design.However,forming a stable energy dissipation mechanism in diagrid framing remains to be investigated to expand its use in regions with high seismicity.To address this issue,a diagrid framing design is proposed here which provides a competitive design option in highly seismic regions through its increased ductility and improved energy dissipation capacity provided by replaceable shear links interconnecting the diagonal members at their ends.The structural characteristics and seismic behavior(capacity,stiffness,energy dissipation,ductility) of the diagrid structural frame are demonstrated with a 21-story building diagrid frame subjected to nonlinear static and dynamic analysis.The findings from the nonlinear time history analysis verify that satisfactory seismic performance can be achieved by the proposed diagrid frame subjected to design basis earthquakes in California.In particular,one appealing feature of the proposed diagrid building is its reduced residual displacement after strong earthquakes.     

方钢管混凝土框架在低周反复荷载作用下的非线性有限元分析

本文建立了方钢管混凝土框架结构的三维非线性有限元分析模型,用以研究方钢管混凝土框架在低周反复荷载作用下的抗震性能。该模型考虑了钢与混凝土的粘结滑移作用。通过与方钢管混凝土框架结构在低周反复荷载作用下试验所得的滞回曲线和刚度退化曲线的对比,发现该模型的计算结果较为精确,可以应用于方钢管混凝土框架的结构分析中。同时由试验和有限元分析计算的结果也可以得出结论,方钢管混凝土框架具有较好的抗震性能。     

复杂条件下烟囱控制爆破拆除方法研究

以三门峡市渑池县化工厂70m高烟囱定向爆破拆除为例,针对在复杂条件下烟囱控制爆破拆除方案的选择,爆破切口、定向窗的设计,爆破参数的选取进行了研究,可为复杂条件下烟囱控制爆破拆除提供参考。     

琼东南盆地深水区断层垂向输导及成藏模式

In the Qiongdongnan Basin, faults are well developed.Based on the drilling results, the traps controlled two or more faults are oil-rich. However, when only one fault cut through the sand body, there is no sign for hy-drocarbon accumulation in the sandstone. In terms of this phenomenon, the principle of reservoir-forming controlled by fault terrace is proposed, i.e., when the single fault activates, because of the incompressibility of pore water, the resistance of pore and the direction of buoyancy, it is impossible for hydrocarbon to ac-cumulate in sandstone. But when there are two or more faults, one of the faults acts as the spillway so the hydrocarbon could fill in the pore of sandstone through other faults. In total five gas bearing structures and four failure traps are considered, as examples to demonstrate our findings. According to this theory, it is well-advised that south steep slope zone of Baodao-Changchang Depression, south gentle slope zone of Lingshui Depression, north steep slope zone of Lingshui Depression, and north steep slope zone of Baodao Depression are the most favorable step-fault zones, which are the main exploration direction in next stage.