Simplified Macro-Model for Infill Masonry Panels

In structural analyses, masonry infill walls are commonly considered to be non structural elements. However, the response of reinforced concrete buildings to earthquake loads can be substantially affected by the influence of infill walls. In this article, an improved numerical model for the simulation of the behavior of masonry infill walls subjected to earthquake loads is proposed and analyzed. First, the proposed model is presented. This is an upgrading of the equivalent bi-diagonal compression strut model, commonly used for the nonlinear behavior of infill masonry panels subjected to cyclic loads. Second, the main results of the calibration analyses obtained with two series of experimental tests are presented and discussed: one on a single frame with one story and one bay tested at the LNEC Laboratory; and the second, on a full-scale four story and three-bay frame tested at the ELSA laboratory.     

Inelastic Displacement Demand of Strength-Degraded Structures

This article presents findings from parametric studies involving nonlinear time-history analyses of inelastic systems with and without strength degradation. Results showed that estimates based on the equal-displacement and equal-energy propositions can be exceeded significantly by the inelastic displacement demands in the acceleration and velocity-sensitive regions of the response spectrum. The displacement demand behaviour is sensitive to the strength degradation and the frequency properties of the ground shaking. With a modest strength reduction factor of 2, the inelastic displacement demand would typically be constrained by the Peak Displacement Demand as indicated on the elastic displacement response spectrum for 5% damping.     

Nonlinear Static Procedure for Multi-Story Asymmetric Frame Buildings Considering Bi-Directional Excitation

The present article focuses on a nonlinear static procedure (NSP) for a multi-story asymmetric frame building with regular elevation subjected to bi-directional ground motion. In this procedure, two simplified models—an equivalent single-story model and an equivalent single-degree-of-freedom (SDOF) model—are used to predict the peak response of multi-story asymmetric buildings. The peak response is predicted through pushover analysis of an equivalent single-story model considering the effect of bi-directional excitations and an estimation of the nonlinear response of equivalent SDOF models. The predicted results are compared with the nonlinear dynamic analysis results, and satisfactory predictions can be obtained by the proposed procedure.     

Natural Frequency of Single Pier Bridges Considering Soil-Structure Interaction

Because of the crucial role of free vibration frequency of a structure (e.g., a bridge) in design procedure, more realistic estimation of the frequency ends up in safer and more optimized design. As obtaining the free vibration frequencies of a bridge, considering soil-pile group-structure interaction, provide more realistic values, development of an analytical model to obtain such free vibration frequencies is studied in this research work. Most researchers have studied models with a single pile foundation. The purpose of this study is to assess soil-structure interaction (SSI) effects on dynamic performance of pile group supported bridges. A new analytical model is proposed to predict seismic analysis of these bridges. Applying the dynamic equations of motion for the system, SSI effects have been estimated. Based on the suggested analytical model, a new approximate equation is proposed for calculating natural frequency of pile group supported bridges. Equation accuracy has been investigated by comparing the results with those achieved by previous studies. Most periods calculated by the approximate equation are similar to those given for other case studies, indicating that the model could be applicable to other projects. Since the proposed model is very similar to real soil-pile-pier systems, this approximate equation can be used in preliminary seismic design of bridges.     

Application of an Extended Bouc-Wen Model in Seismic Response Prediction of Unbonded Fiber-Reinforced Isolators

The focus of this article is on seismic-response prediction of Stable Unbonded-Fiber Reinforced Elastomeric Isolators (SU-FREIs). The lateral load-displacement of a SU-FREI can be characterized with a gradual softening that is followed by stiffening. An extended Bouc-Wen Model is developed to simulate the response behavior of SU-FREIs under seismic events. To examine the accuracy of model, the response of a base isolated structure to different input earthquakes were simulated and compared with the results of a previous shake table study. Results of this study indicate that the proposed Bouc-Wen Model is robust and reasonably accurate in seismic analysis of SU-FREIs.     

Equivalent Damping Ratio Equations in Support of Displacement-Based Seismic Design for Pile-Supported Wharves

This study primarily proposes new equivalent damping ratio equations based on Jacobsen’s approach for displacement-based seismic design of pile-supported wharves to account for wharf configurations and soil-pile interaction. It is found that Pivot hysteresis model and Masing rule can accurately capture nonlinear behavior of concrete and steel wharves, respectively. To verify applicability of proposed equations, analyses were conducted to three typical wharves to make a comparison of maximum displacements obtained from nonlinear time-history analyses and substitute structure method with various damping equations. The verification reveals proposed equations are better than those in practice for their higher precision in determining displacements.     

明清时期海岛开发模式研究

明清时期,中国沿海地区很多居民以不同方式纷纷移居和开发中国近海海岛,使中国近海海岛的开发由传统单一的开发模式开始向以渔业、农业、海上走私贸易等为主的多样并举的开发模式转变。本文对明清时期海岛的开发模式进行了探讨,并就海岛开发模式的差异性及原因提出一些自己的看法。     

南京夫子庙历史文化街区景观偏好的游后感知实证研究

本文以历史文化街区为例,运用瑟思顿态度比较评价模型,定量测度了游客对南京夫子庙景观偏好的游后感知特征。研究结果显示:(1)从时间维度分析,游客对夫子庙的时间感知差异随参观时间的流逝不断升华,逐渐由浅层次的一般性体验上升至深层次的高峰性体验,进而演化成整体感知中最核心的体验要素;从内容分析,游后感知呈现出与空间感知分异相对应的儒学文化→商业文化→雅士文化依次递减的特征;总体而言,游客对夫子庙游后感知差异存在光环区、亚光环区和灰度区三个区段。(2)旅游开发使夫子庙儒学文化受到其它文化干扰,商业文化存在"泛商业化现象",雅士文化存在传承载体和方式的弱化。属于自己特有的文化内涵如何传承应引起重视。     

旅游信息来源类型对消费者行为意图的影响

如何高效利用和改变消费者对信息来源的判别特点,并使其在营销战略设计中发挥作用,是营销人员重点关注的现实命题。通过了解消费者对信息来源类型的利用程度,营销人员可以运用高效方式来设计和影响传播渠道。本研究在实体化旅游信息来源类型的基础上,通过构建量表实测,定量化分析了旅游信息来源类型对消费者行为意图的影响。结果显示:(1)消费者认知对旅游信息来源类型有明确的界定和划分,不同类型的旅游信息来源会呈现规律的聚类现象;(2)人际传播的旅游信息来源对消费者行为意图仍然发挥着独特的影响作用;(3)有效阅读时间是旅游信息来源类型对消费者行为意图产生影响的重要限制因素;(4)电视和休闲媒介类旅游信息传播效果对消费者行为意图影响不大。该结论对旅游营销广告投放及营销渠道选择均具有一定的参照意义;(5)人口结构特征中,职业和月收入差异对旅游信息来源类型选择影响较大;性别、年龄、教育程度及年出游次数对旅游信息来源类型选择影响较小。     

基于引力模型的关中城市间联系测度分析

在新一轮西部大开发进程中,为提升关中城市群整体实力,需要对关中城市间经济联系度进行科学测量,找出其中存在的问题、原因与解决对策。本文借鉴国内外学者分析城市间联系测度的方法,以标准引力模型为基础,在对关中城市的中心等级进行科学划分和可达性分析的基础上,测量了关中城市间的联系程度,找出关中城市群发展的现存问题,并提出从行政区划适当调整、发展规划与组织协调、财政体制完善、壮大县域经济发展等方面来促进关中城市群发展。