Experimental seismic evaluation of old concrete columns reinforced by plain bars

Concrete buildings reinforced by plain (smooth) bars are one of the special types of old reinforced concrete buildings that were generally built before the 1970s. As columns are generally the most important structural members of a framed structure, understanding their realistic seismic behavior is very helpful in estimating structural deformations, forces and energy dissipation capacities. Furthermore, in most of old‐framed building structures, columns play a key role in the final behavior because of strong beam–weak column conditions. This article reports the results of experimental monotonic and cyclic tests on four concrete column specimens reinforced by plain bars and with various types of splices. Through the experimental results, it tried to obtain more clarification on the complicated behavior of such old reinforced members as well as the differences compared with relevant results of columns reinforced by deformed bars. It was realized that slip (fixed‐end rotation) contribution is the major source of deformation in all specimens independent from type of splices. Moreover, general mode of behavior was restrained‐rocking action independent of type of splice detailing. A simple theory for the explanation of hysteresis force–displacement response was proposed. The theory assumes a concrete block rocking element that is restrained with plain bars at both ends. Copyright © 2010 John Wiley & Sons, Ltd.     

Aqueous Slip Casting of Transparent Aluminum Oxynitride

Highly transparent Aluminum oxynitride (AlON) body has been produced using aqueous slip casting technique. High‐purity alumina and AlN were used as raw materials for the synthesis of single‐phase AlON powder. As‐synthesized AlON powder was surface modified to enable the AlON powders resistant to hydrolysis in water during aqueous slip casting. High solid loaded aqueous AlON slip was prepared for casting followed by drying and sintering to produce transparent AlON. Phase formation and stability was characterized by XRD, pH, and viscosity measurements. AlON powders before and after surface treatments were characterized. Sintered transparent AlON samples were characterized for their mechanical, microstructural, and optical properties. Sintered and polished AlON produced in this study has shown inline transparency up to 80% between 0.22 and 6 μm wavelength region.     

考虑土体强度不均匀性时宽窄基坑坑底隆起稳定研究

在基坑坑底隆起稳定性分析中,准确的破坏模式及滑动面是确定安全系数的基础。然而,基坑坑底隆起破坏模式种类繁多且形式各异。传统的经典基坑坑底隆起稳定分析以及规范分析方法在破坏模式及滑动面的选取上均存在差异和局限性。基于不连续布局优化法,首先研究了土体强度不均匀性对不同宽度基坑坑底隆起稳定性的影响。结果表明,软土层厚度较大且土体强度沿深度逐渐增长时,宽基坑坑底隆起滑动面并不覆盖整个坑底,即相当于软土层下部存在一硬土层,限制了滑动面向下延伸。进一步,分析了围护结构长度及抗弯强度对破坏模式及安全系数的影响,并提出以滑动面触碰围护结构来区分宽窄基坑。在宽基坑中,当围护结构嵌固深度较小时,失稳破坏滑动面并不通过桩底,此时应用绕最下道支撑的圆弧滑动模式时应适当修正滑动面半径。对于窄基坑,应用圆弧滑动模式时需修正坑内滑动面,以考虑窄基坑的空间效应对安全系数的提高作用。     

河北南埝峪金银矿成矿模式及找矿潜力分析

文章通过对河北省涞水县南埝峪金银矿区域地质背景、矿区地质特征、矿体地质特征及区内地球物理、地球化学特征和成矿规律等综合找矿信息的研究,结合区域找矿成果,确定了本区拆离滑脱带型金银矿成矿模式。结合前期工作成果及本次研究表明,矿区具备了形成中—大型规模金银矿床的潜力。     

层间滑动构造的定量研究

层间滑动构造是煤矿上普遍存在的一种地质构造，它一般可分为揉皱型、断滑型及断滑型3种类型。结合层滑构造的发育规律建立了一套可行的定量评价指标体系，并借助这些指标进行了模糊综合评判，从而确定了井田不同块段的层滑类型，再利用不同类型的层滑特征及其发育规律指导煤矿构造评价，实现理论与实践的结合与提高。     

边坡稳定性的动态规划研究及其工程应用实例

研究了动态规划法确定边坡非圆临界滑动面的方法，并应用于大新锰矿边坡稳定性研究，取得良好效果，工程应用实例表明该方法对复杂地质条件的边坡稳定性分析具有广泛的应用前景。     

井巷锚注加固技术应用评价与发展前景

针对任楼煤矿巷道失修状况及原因进行了深入分析,根据多年的实践经验,提出了合理的解决办法,并对今后巷道施工与修护加固参数进行优化设计。     

[分布式驱动电动汽车动力学控制]基于转矩协调分配的分布式驱动电动汽车稳定性控制

A hierarchical vehicle-stability-control method was presented based on the longitudinal force distribution optimization for the handling and stability control of the distributed-driven electric vehicles. The eight-degree-freedom vehicle models and the three-layer control systems were developed. By selecting the sideslip angle and the yaw rate as the state variables and introducting the virtual control to decouple two control variables,  the integral 2-DOF vehicle models were adopted to calculate the equivalent yaw moments for the vehicle stability in upper controllers. The linear quadratic regulator （LQR） method was utilized to optimize the distribution of the front and rear steering angles and the tire longitudinal forces in middle controllers. The sliding-mode-based slip controller in the lower layer was also designed to reallocate the wheel torques. Simulation results show that the control system may make full use of the adhesion potential of the tire under high speed and extreme conditions, realize the coordinated distribution of wheel torques and improve the steering stability of the vehicles. When the actuators fail, the system may reconstruct effectively and realize the reallocation of control inputs to improve the safety of the vehicles.