Considering Soil-Nonlinearity Effect on Seismic Performance Evaluation of Structures based on Pushover Analysis

According to the most of current seismic codes, nonlinear soil behavior is commonly ignored in seismic evaluation procedure of the structures. To contribute on this matter, a pushover analysis method incorporating the probabilistic seismic hazard analysis (PSHA) is proposed to evaluate the effect of nonlinear soil response on seismic performance of a structure. The PSHA outcomes considering soil nonlinearity effect is involved in the analysis procedures by modifying the site-specific response spectrum. Results showed that incorporation of nonlinear soil behavior leads to an increase in displacement demand of structures which should accurately be considered in seismic design/assessment procedure. Results of implemented procedure are confirmed with the estimated displacement demand including soil-structure interaction (SSI).     

Design Principles for Minimum Torsional Response of Wall-Frame Concrete Structures

A seismic design procedure is described incorporating the well-accepted property that the stiffness of reinforced concrete elements is strength dependent and the requirement that the method of assigning strength to elements should be aiming at minimum torsional phenomena. Such a response allows a direct comparison with the findings of a static nonlinear analysis, which may provide the limits of story drifts and the induced plastic rotations in potential plastic hinges. The requirement of a practically translational response implies that the element strength assignment should be based on planar considerations and the initially elastic response should be of minimum torsion.     

Design of Passive Viscous Fluid Control Systems for Nonlinear Structures Based on Active Control

A practical procedure is developed for the design of passive control systems using viscous fluid dampers for nonlinear structures. The design methodology takes advantage of the modification of the damping, strength, and stiffness properties of the structure to achieve the desired relative displacement and absolute acceleration response. For this purpose, a study of poles in the complex plane is used to determine the required changes in the dynamic properties of nonlinear structures. Furthermore, a relatively simple relation between the ductility demands of highly damped single- and multiple-degree-of-freedom (SDF and MDF respectively) systems is established to reduce the computational burden of the proposed design method.     

统计分析在商代陶鬲研究中的应用

统计分析的方法应用于考古学是以定量化的研究代替定性分析的过程。本文将因子分析的方法应用于郑州洛阳地区出土陶器器形的研究中,以描述陶鬲形制的变化,并检验此变化和商文化演进间的关系。     

'Geographical Expeditions': Assessing the benefits of a student-driven fieldwork method

A student-driven fieldwork method, focused in a local metropolitan area, is described and assessed. Developed for a second-level course in cultural geography, it was inspired by the 'Geographical Expeditions' originally devised by William Bunge in the 1960s. It is one solution to maintaining fieldwork in the syllabus for a large class, at the same time as providing benefits for participants in terms of challenge and autonomy. Student responses are compared with the merits of fieldwork as claimed in the literature. In view of concerns expressed about increasing student 'disengagement' from commitment to university study, active participation in a 'Geographical Expedition' is a strong motivating factor.     

Floor Response Spectra for Bare and Infilled Reinforced Concrete Frames

The objective of this article is to study the effects of structural nonlinear behavior on Floor Response Spectra (FRS) of existing reinforced concrete frames. This study examines how the FRS vary with the level of post-elastic behavior in buildings of different number of stories and masonry infill wall configurations. The effect of damping modeling assumptions is also investigated. Differences and similarities with findings from the literature are discussed. On the basis of the obtained results, a commentary on the adequacy of basic assumptions used in predictive equations proposed by different seismic codes is offered.     

Seismic Behavior of FRP-Retrofitted Reinforced Concrete Frames

Although a significant number of studies have been conducted on the behavior of the reinforced concrete beam-column joints retrofitted with FRP materials, limited investigation considered the overall seismic behavior of the retrofitted frames. In this article, experimental and numerical studies are performed on a scaled-down eight-story and two full scaled low-rise ordinary moment resisting frames (OMRFs) retrofitted with FRP at the joints. Additional, rotational stiffness of the joints is implemented into pushover models to predict seismic performance and behavior factor of the retrofitted frames. Results indicate that FRP retrofitting is more effective than steel braces for low- and medium-rise OMRFs.     

浅谈初中英语教学中的学生自主学习

自学能力的培养对学生获得知识、获得其它能力的发展有促进和加速作用。在中学阶段培养学生英语自学能力是非常重要的,这需要教师在教学过程中对学生进行有计划、分层次的训练,激发学生的求知欲,使自学成为他们内在的需要,使学生从苦学到乐学,从学会到会学,他们才能真正获得适应社会需要的学习能力。     

传统水硬性灰浆性能的影响因素综述

水硬性灰浆是性能优良的传统建筑材料,其相比于气硬性灰浆,有更好的防水性、透气性、耐冻性、耐盐结晶性和机械强度等,适合作为古建筑的修复材料。本研究对影响传统水硬性灰浆性能的因素进行归纳综述,探讨无机物(胶凝材料、骨料、水)、天然有机物(多糖类、蛋白质类、油脂类)、养护条件等对水硬性灰浆性能的影响。其中,无机物对水硬性灰浆的性能影响一方面取决于胶凝材料的特性,另一方面取决于灰浆中不同无机组分间的比例;在水硬性灰浆中加入多糖类有机物可提高灰浆力学性能,加入蛋白质类有机物可提高防水性和孔隙率,加入油脂类有机物可大幅提升防水性、耐久性;在高相对湿度条件下养护水硬性灰浆可提高其机械强度,而低湿度条件下养护的灰浆则更具耐久性。本研究成果可为认知、揭示传统水硬性灰浆的科学价值,研究、开发新型古建保护修复材料提供参考与启示。