专业英语翻译

Behavior of retrofitted reinforced concrete beams under combined bending and torsion: A numerical study

①ABSTRACT: This paper presents the numerical study on unretrofitted and retrofitted reinforced concrete beams subjected to combined bending and torsion. Different ratios between twisting moment and bending moment are considered. The finite elements adopted by ANSYS are used for this study. For the purpose of validation of the finite element model developed, the numerical study is first carried out on the unretroffited reinforced concrete beams that were experimentally tested and reported in the literature. Then the study has been extended for the same reinforced concrete beams retrofitted with carbon fiber reinforced plastic composites with 45±and 90/0fiber orientations. The present study revels that the CFRP composites with 45±fiber orientations are more effective in retrofitting the RC beams subjected to combined bending and torsion for higher torque to moment ratios. ②NUMERICAL STUDY Finite element modeling

Solid 65, a 3-D structural reinforced concrete solid element was used to model the concrete. This element is capable of cracking in tension and crushing in compression. It is defined by eight nodes having three translation degrees of freedom at each node. The important aspect of this element is the treatment of nonlinear material properties. Though Solid 65 is a ①摘要：本文主要介绍了弯扭组合状态

下未经翻新和经过改进的钢筋混凝土梁（RC 梁）的数值模拟研究，考虑了不同的扭弯比状态，并将ANSYS 中所采用的有限单元用应于此项研究。为了验证经改进的有限单元模型的有效性，首先，本文对未经翻新的钢筋混凝土梁进行数值研究，而这种钢筋混凝土梁此前已经通过试验的方式进行测试，并将研究结果发表于文献。其次，本文将数值研究推广到经过改进的钢筋混凝土梁，这些梁是通过纤维方向分别为

45±和

90/0的碳纤维塑料复合材料（CFRP 复合材料）进行强化的。结果表明，高扭弯比下

45±纤维方向的CFRP 复合材料对于提高钢筋混凝土梁强化效应具有显著作用。 ②数值研究

有限单元模型

“实体65”单元是一种三维结构钢筋混凝土单元，可用于模拟混凝土材料。这种单元能够分别在张拉和压缩作用下产生开裂或压碎现象。“实体65”单元通过8个结点定义，每个结点有3个平移自由度，该单元的一

reinforced

concrete

element,

the

reinforcement capability of this element was not considered in this study. All the reinforcements were modeled separately using Link 8 , a 3-D spar element which is an uniaxial tension-compression element defined by two nodes with three translational degrees of freedom at each node. This link 8 element is also capable of plastic deformation. Solid 45, a 3-D structural solid element was used to model the steel plates at the support and under the load. A layered solid element, Solid 46 was used to model the CFRP composites.

③CONCLUSION

A finite element analysis has been carried out to study the flexural behavior with respect to the stiffness and strength of RC beams strengthened for combined bending and torsion. Based on the results obtained form the numerical study, the major conclusions drawn are summarized below.

●I n strengthened beams, the addition of FRP laminate has no significant effect on the initial stiffness of beams.

●Strengthening of RC beams with FRP is found to be effective only after the initial cracking of concrete.

●The FRP composites wrapped around the beams are effectively utilized in improving the load capacity with increase in the twisting moment to bending moment ratio.

●The laminates with 45

±fiber orientations are found to be more effective for higher values of twisting to bending moment ratios.

个重要应用是处理非线性材料特性。虽然“实体65”单元是一种钢筋混凝土单元，但本研究中并未考虑它的强化能力。因此，所有的加固材料均另外使用“连杆8”单元进行模拟，这种单元是一种3维杆单元，只能受单向拉压作用，它通过两个结点定义，每个结点有3个平移自由度，此外，这种“连杆8”单元还可以模拟塑性变形。“实体45”单元是一种3维结构单元，可以用来模拟荷载作用下支撑处的刚性平面。通过将“实体46”单元分层设置，就可以模拟CFRP复合材料。

③结论

本文对弯扭组合作用下与钢筋混凝土梁刚度和强度相关的挠曲行为进行了有限单元分析，基于数值研究的结果，主要结论如下：

●对加固梁而言，附加的纤维塑料强化层对梁的初始刚度无显著影响。

●结果表明，只有当混凝土起裂之后，加固的钢筋混凝土梁才起到明显作用。

●随着扭弯比的增加，梁外围的FRP 复合材料可显著提高梁本身的负载能力。

●高扭弯比下， 45

±纤维方向的强化层的作用效果更为突出。

Overturning of Non-Structural Components in Low-Moderate Seismicity Regions

①ABSTRACT: The objective of this paper is to review key issues concerned with the proper engineering of non-structural components in buildings for their safe and satisfactory performances in projected seismic conditions in regions of low and moderate seismicity.Initially, the paper provides an overview of the conventional force-based provisions for the calculation of the required strengths for full restraints of non-structural components. Given the relatively small displacement demand of the ground in conditions of low and moderate seismicity, provisions for protection of non-structural components should only target at items which have been identified to be vulnerable to overturing and their failure can have serious consequences. In this context, the displacement-based (DB) model for overturning and its linearisation is presented. The DB model can potentially become very useful as technical reference when when it comes identifying potentially hazardous items which risk overturning if unrestrained. The paper concludes with a discussion on engineering for earthquake safety in buildings in a broader context than merely requlating the structural design of the building.

②The component amplification factor

(c a) typically varies between 1 for components which are generally regarded as rigid and 2.5 for flexibly ①摘要：本文的目的是在中低等强度地震地区相应的地震条件下，对建筑中与非结构性部件相应工程相关的关键问题进行评价，这些问题往往与建筑物安全性和满意度表现紧密相关。首先，在非结构性部件全约束条件下，本文对传统上采用的基于力的强度计算规定进行综述。假定中低度条件下允许地面发生微小位移，那么保护非结构性部件的设计规范应主要针对地震中已表明更容易倒塌的建筑物，因为它们的破坏会导致严重灾害。本文提出了针对倾倒和线性化条件下的基于位移的模型（DB模型）。一些建筑物在去除约束后极有可能发生倾倒，当测定工作涉及这些条件时，采用DB 模型就会变得非常有效。本文并非直接规定建筑物的结构设计，而是通过上下文讨论建筑工程中的地震安全问题，从而得出最终结论。

②部件放大系数（c a）在1和2.5之间特殊地变化，其中当部件视为刚体时1

c

a，当视为柔性固定部件或弹簧分

mounted components, or spring isolated components. In the NEHRP recommendations, values of c a are clearly stated for different component types. In the New Zealand Standard, the response behavior of the component and its mounting is modeled in a manner similar to that for the aseismic design of a building. Thus, the inelastic response spectra stipulated in the Standard tor the calculation of the seismic forces applied to the side of a building are also used for the calculation of the seismic forces applied to a non-structural component. With this calculation approach,the amplification response behavior and the energy dissipation characteristics of the component mounting are covered by similar factors.

③Design regulations alone would not necessarily improve the level of preparedness significantly (because regulations for controlling the design of a new building would not cover for installations and disposition of storage items during its service life). The engineering of non-structural components and building contents for countering potential earthquake hazards should not be restricted to merely designing restraints, and particularly so for regions of low and moderate seismicity. The author proposes that inspection procedures for countering the risks of fire be broadened to address a diversity of potential hazards including earthquake hazards given that they are all to do with the safe and proper utilization of space and the storage of hazardous items. 离组件时5.2

c

a。NEHRP建议以

c

a值的大小代表不同类型的构件。在新西兰标准中，组件的相应行为及装配的建模方式类似于建筑物的抗震设计方法。因此，非弹性频谱也可以用来计算作用于非结构性部件的地震荷载大小，而这种频谱是由施加于建筑物侧面地震荷载的计算标准所规定的。通过采用这种计算方法，相似系数中就能够包含组件的响应放大行为和能量耗散特征两个因素。

③仅靠设计规范不一定会显著提高防备水平（因为这些规定虽然规定了新建筑物的设计方式，但却不能决定建筑物使用过程中储存物品的安装和配置）。对于有潜在地震危险的非结构构件和建筑内容的工程，尤其对中、低度地震活动地区的工程来说，不应仅仅局限于设计规范的约束。作者提出，只要危害与空间安全、合理利用及危险品的存储紧密相关，那么控制火灾风险的检测程序就应加以拓宽，以应对包括诸如地震等的多样性潜在危害。