Smart Lead Rubber Bearings Equipped with Ferrous Shape Memory Alloy Wires for Seismically Isolating Highway Bridges

Shape memory alloys (SMA) can substantially improve the damping capacity and re-centering capability of elastomeric isolators. The objective of this study is to assess the seismic performance of smart lead rubber bearings (LRBs) equipped with double cross ferrous SMA wires. Hysteretic shear response of SMA wire-based LRB is determined using finite element method. The seismic response of a multispan continuous steel girder bridge isolated by SMA-LRB is evaluated. Hybrid SMA-LRB bearing exhibits a significantly lower shear strain demand (up to 46% reduction) and a higher energy dissipation capacity (up to 31% increase) compared to the LRB.     

徐州狮子山汉楚王陵彩绘陶俑的保护研究

为对徐州狮子山出土的彩绘陶俑进行保护,我们对陶俑本体进行了分析,采用扫描电子显微镜（SEM）对陶俑表面进行微观形貌分析;X射线荧光光谱仪（XRF）分析化学成分;通过岩相分析,并结合XRD分析、热重和差示热分析（TG-DSC）从而推测陶俑的烧成温度;电子能谱仪（EDS）对彩绘表面颜料的进行成分分析。在此基础上,采用7种化学材料进行对比实验,对外观、颜色光泽度变化、固化物形成期、防水接触角、吸湿等温线、吸水率、抗压强度进行了观察和分析,同时,还进行了紫外光耐老化试验。试验表明,氟橡胶不仅有较好的渗透率和膜层外观及相对较强的抗压能力的优点,而且还有较好的耐老化性能。经过对狮子山出土的一尊彩绘陶俑利用氟橡胶进行保护后10多年的观察,陶俑的表面色泽、防水与接触角、颜料表面的固结强度等状态保持良好。因此,在保护彩绘陶俑方面,氟橡胶是值得考虑的一种材料。     

1952年《中苏橡胶协定》与20世纪50年代的云南农垦

1952年9月15日,中苏两国在莫斯科签署《中华人民共和国中央人民政府、苏维埃社会主义共和国联盟政府关于帮助中华人民共和国植胶、割胶、制胶及售与苏联橡胶的协定》。该协定在扩大中国橡胶生产、派遣苏联专家到中国担任顾问、贷款和还款、售与苏联橡胶、移民云南等方面对20世纪50年代云南农垦系统的发展产生了重要影响。     

A Base Isolation System for Developing Countries Using Discarded Tyres Filled with Elastomeric Recycled Materials

This article studies the performance of economic base isolators using tyres filled with elastomeric recycled materials. The research was conducted to analyze base isolators to be used in developing nations, where the application of conventional elastomeric rubber bearings due to economic reasons is limited.

The tested isolators are made of kart tyres filled with different recycled elastomeric materials and aggregates. Dynamic and static tests proved acceptable vertical to horizontal stiffness ratio of the bearings and shake table tests showed an excellent enhancement of the base isolated structural response compared to the corresponding fixed base structure.     

Seismic Tests and Numerical Modeling of a Rolling-ball Isolation System

For the seismic isolation of light structures, the use of laminated rubber bearings is neither economical nor, for most cases, technically suited. For the isolation of this type of structure a new system, consisting of steel balls rolling on rubber tracks, has been developed at TARRC (Tun Abdul Razak Research Centre).

This article presents the results of experimental tests carried out for the characterization of the behavior of this new device. A numerical model is also proposed that can be used to assess the seismic response of structures with this isolation system.

Comparison of the predictions of the numerical model with the experimental data shows that the model is adequate to perform the correct assessment of the seismic response of isolated structures. The results of the experimental campaign of shaking-table tests, as well as the numerical simulations, show that there is an effective reduction of the acceleration levels induced in the isolated structures.     

Material Modeling in the Dynamic Nonlinear Analysis for Recycled Aggregate Concrete Structures

Dynamic mechanical tests of recycled aggregate concrete (RAC) test units confined by transverse hoop reinforcement are carried out. The effects of the strain rate, hoop reinforcement confinement, and replacement ratio of recycled coarse aggregate (RCA) on the mechanical properties of confined recycled aggregate concrete (CRAC) are thoroughly analyzed and assessed. The strain-rate-dependent constitutive model of CRAC is proposed for the high strain rate representative of seismic conditions. A three-dimensional discrete numerical model, based on the proposed rate-dependent material model of CRAC, is established to investigate and evaluate the dynamic nonlinear behaviors of RAC structures.