Evaluation of IBC Equivalent Static Procedure for Base Shear Distribution of Seismic Isolated Structures

It has been pointed out that the static lateral response procedure for base isolated structures presented in IBC somewhat overestimates the seismic story force [Lashkari and Kircher, 1993 Lashkari, B. and Kircher, C. A. . Evaluation of SEAOC/UBC analysis procedures, Part 1: Stiff superstructure. Proceedings of a Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control. Redwood City, California. ATC Report 17-1.  [Google Scholar]; Constantinou et al., 1993 Constantinou, M. C., Winters, C. W. and Theodossiou, D. . Evaluation of SEAOC and UBC analysis procedures, Part 2: Flexible Superstructure. Proceedings of a Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control. Redwood City, California. ATC Report 17-1.  [Google Scholar]]. In this article IBC equivalent static method for base shear distribution of seismic isolated structures is evaluated. For this purpose one-story to six-story building models are designed according to equivalent lateral response procedure for different elastomeric isolation systems. The results of equivalent lateral response procedure in parameters such as base shear and vertical distribution of base shear are compared with results obtained from dynamic nonlinear analysis and the efficiency and limitations of its application are investigated. In general, the results of equivalent lateral response procedure in base shears are acceptable within the scope of this procedure, but the proposed triangular distribution of base shear is somewhat conservative. So a new formulation for vertical distribution of base shear is proposed which results in a more realistic distribution of shear over the height of isolated buildings. The accuracy of the new formulation is examined by comparing the resulting responses obtained from this study with those calculated by nonlinear time history analysis.     

A Static Nonlinear Procedure for the Evaluation of the Elastic Buckling of Anchored Steel Tanks Due to Earthquakes

Ground-supported steel tanks experienced extensive damage in past earthquakes. The failure of tanks in earthquakes may cause severe environmental damage and economic losses. This study deals with the evaluation of the elastic buckling of above-ground steel tanks anchored to the foundation due to seismic shaking. The proposed nonlinear static procedure is based on the capacity spectrum method (CSM) utilized for the seismic evaluation of buildings. Different from the standard CSM, the results are not the base shear and the maximum displacement of a characteristic point of the structure but the minimum value of the horizontal peak ground acceleration (PGA) that produces buckling in the tank shell. Three detailed finite element models of tank-liquid systems with height to diameter ratios H/D of 0.40, 0.63, and 0.95 are used to verify the methodology. The 1997 UBC design spectrum and response spectra of records of the 1986 El Salvador and 1966 Parkfield earthquakes are used as seismic demand. The estimates of the PGA for the occurrence of first elastic buckling obtained with the proposed nonlinear static procedure were quite accurate compared with those calculated with more elaborate dynamic buckling studies. For all the cases considered, the proposed methodology yielded slightly smaller values of the critical PGA for the first elastic buckling compared to the dynamic buckling results.     

A Modified Capacity Spectrum Method with Direct Calculation of Seismic Intensity of Points on Capacity Curve

A direct methodology for solving the seismic intensity of each point on the capacity curve is proposed. By utilizing the procedure, a continuous curve between the structural response and the seismic intensity, the structural response function, can be easily generated. Unlike previous procedures that search for the performance point of a determined seismic intensity, the proposed methodology easily draws the full curve without iterations. The procedure is applicable to both a smooth design spectrum and an actual response spectrum. Examples indicate the methodology is accurate and fast, and convenient to be combined with existing procedures, such as Modal Pushover Analysis.     

Seismic Vulnerability Assessment of an Infilled Reinforced Concrete Frame Structure Designed for Gravity Loads

In the last decades, particular attention has been paid to the seismic vulnerability of existing reinforced concrete buildings designed for gravity loads only. Such buildings, designed before the introduction of capacity design in modern seismic codes, are very common, particularly in seismic prone countries of the Mediterranean area. Due to poor detailing and lacking of capacity design principles, high vulnerability has been highlighted in several past studies. In this article, inadequate seismic response and peculiar damage pattern are investigated by means of shake table tests performed on a 1:2 scaled 3-story infilled prototype. Particular attention is given to the role of beam-column joints and frame-panel interaction. The effectiveness of the EC8-based assessment approach is then evaluated; both linear and nonlinear numerical models, with different levels of sophistication, have been implemented in order to explore their behavioral aspects.     

Testing Methods of Record Linkage on Swedish Censuses

Abstract.

Research benefits a great deal when different kinds of registers can be combined. Record linkage is an important tool for connecting sources to create longitudinal databases of individual data. In this article, researchers test and evaluate different methods of record linkage used when linking two censuses. By comparing the results of the census linkage with other continuous Swedish parish registers, they find that applying constructed name variables and household links considerably increases the success rate without the risk of introducing bias. Missing links are mainly related to name problems, and appear most frequently among children and when the family structure has changed between the censuses. Faulty links are very few and must be regarded as only a marginal problem for analysis. The study underlines the importance of adapting the linkage process to the special characteristics of the sources.     

Seismic Evaluation of Tall Buildings Using a Simplified but Accurate Analysis Procedure

A simplified analysis procedure for evaluating the nonlinear seismic responses of tall reinforced concrete (RC) buildings is examined in this study. It is called the Uncoupled Modal Response History Analysis (UMRHA) procedure. It can be viewed as an extended version of the classical modal analysis procedure, where the nonlinear response of each vibration mode is first computed, and they are later on combined into the total response of the structure. The procedure requires the knowledge of the modal hysteretic behavior, which can be obtained from a cyclic modal pushover analysis. The responses of four tall buildings in Bangkok to distant large earthquakes are computed by this procedure and compared with those obtained from the Nonlinear Response History Analysis (NLRHA) procedure. These four buildings have different heights—varying from 20 to 44 stories, different configurations of floor plan, and different arrangement of RC walls. The comparison shows that the UMRHA procedure is able to accurately compute the story shears and story overturning moments, floor accelerations, and inter-story drifts of all these tall buildings. The required computational effort is also extremely low compared to that of the NLRHA procedure. Moreover, since the UMRHA procedure computes the response of each individual vibration mode, it provides more understanding and insight into the complex nonlinear seismic responses of these tall buildings.     

实现地方经济立法科学化民主化规范化的文化障碍与路径选择

实现地方经济立法科学化、民主化与规范化,是保障地方经济立法质量、确保地方经济立法合法性、维护法制统一与立足地方实际的客观要求。传统的文化和立法观念阻碍地方经济立法质量的提高。对此,应当采取有针对性的措施。即树立科学的立法观念,加强地方经济立法的预测与调研;彰显公民本位理念,扩大地方经济立法过程中的公民参与;摈弃传统保守立法观,规范地方经济立法的文本语言。     

Computing Abilities in Antiquity: The Royal Judahite Storage Jars as a Case-study

Studying the volume of ancient pottery vessels can shed light on the development of complex societies and state apparatus by revealing the means taken to standardize trade and taxation. It can also shed light on the cognitive abilities of ancient people by investigating their knowledge of computing. This paper explores, as a case study, the volume and shape of the lmlk (“belonging to the king”) royal storage jars, which probably represent the highest level of standardization in eighth century BCE Judah. To estimate the volume of these vessels we constructed a computer 3D model for each jar. The variation in the jars’ linear dimensions is about 2–3%, a number that is characteristic of human-made objects produced by professionals without employing measurement tools. Had the potters produced jars of the same height, they could have easily reached 3–4% accuracy in the volume. Surprisingly, the variation in the jars’ volume is 7–10%. We hypothesize that rather than height the potters focused on the jars’ shape and wall width, estimating the volume according to the jars’ outer measurements. We propose a simple way that these measurements could have been taken and suggest a formula that could have been employed by the potters and customers for quickly calculating a jar’s volume.     

国际旅游文献中若干术语的汉译表述：问题与探讨

专业术语的统一及其规范化使用是一个学科得以成立的必要条件之一,并且在反映一个研究领域的学术规范方面,也是最为明显的外在表现。本文通过比较国际文献中对有关术语的使用,分析了国内旅游研究中在若干英文术语的汉译表述上普遍存在的问题,并就这些概念的本意及其作为专业术语的规范化使用提出了一些思考,以使国内旅游学术研究更加严谨。     

A Five-Step Procedure for the Dimensioning of Viscous Dampers to Be Inserted in Building Structures

Viscous dampers have widely proved their effectiveness in mitigating the effects of the seismic action upon building structures. In view of the large impact that use of such dissipative devices is already having and would most likely have soon in earthquake engineering applications, this article presents a practical procedure for the seismic design of building structures equipped with viscous dampers, which aims at providing practical tools for an easy identification of the mechanical characteristics of the manufactured viscous dampers which allow to achieve target levels of performances. Selected numerical applications are developed with reference to simple, but yet relevant, cases.