A Procedure for the Displacement-Based Seismic Assessment of Infilled RC Frames

The aim of this study was to propose an extension of the displacement-based assessment procedure for infilled reinforced concrete (RC) frames. Two fundamental steps of the displacement-based approach were studied: the determination of the equivalent viscous damping and the definition of the limit-state displacement profile. The proposed criteria were derived by examining the results of two different numerical investigations regarding the nonlinear seismic response of single- and multi-story infilled RC frames. Lastly, the effectiveness of the method was verified through comparisons, in terms of displacement demand, with the results of nonlinear dynamic analyses.     

Application of Endurance Time Analysis in Seismic Evaluation of an Unreinforced Masonry Monument

In this article, seismic behavior of the main dome of a well-known middle-eastern historical- monument, “Imam Reza Shrine” (Mashhad, Iran) which is located in a high seismic area in Iran is evaluated. This study focuses on the response history analysis using intensifying dynamic excitations in the framework of Endurance Time Method. Endurance Time Analysis gives acceptable results for a wide range of earthquake intensities and considerably reduces the computational demand in comparison to the conventional Time History Analysis and Incremental Dynamic Analysis. The aim of this study is to investigate the applicability and efficiency of Endurance Time Analysis for masonry monuments and to suggest modifications and interpretations to improve compatibility of the results with Time History Analysis. In addition, to facilitate evaluation of the structural behavior, a dimensionless index, Cumulative Plastic Strain Index, is proposed as a criterion to compare structural performance in terms of the severity and the extent of damage as a function of earthquake intensity.     

Bison Bone Fragmentation and Survivorship: a Comparative Method

Zooarchaeologists usually describe a bone fragment as a particular portion or segment using terminology based on skeletal orientation (e.g. proximal, anterior, lateral). A more precise understanding of bone fragmentation can be achieved by naming portions for discrete anatomical features and defined zones. Since the anatomical features are the diagnostic criteria for identifying and orienting bones, each specimen normally has at least one such portion, and a complete element contains all of them. This recording method facilitates study of the relationship between survivorship and volume density, and it enhances inter-site comparisons. The method employs the minimum number of elements (MNE) and minimum animal units (MAU) across a site-wide aggregate. Although illustrated here with an analysis of bison bones, the method can be adapted for the study of other taxa as well as for inter-species comparisons.     

Reliability-based Strength Amplification Factors for Structures with Asymmetric Yielding

A reliability-based methodology to estimate strength amplification factors for structures with asymmetric yielding is proposed. The approach is based on structural demand hazard analyses. Nonlinear time-history analyses of tridimensional simplified systems are carried out. The effects of two orthogonal components of the seismic ground motions and soil-structure interaction, are considered. Results show that the expected ductility demand of systems with asymmetric yielding may be much higher than those of symmetric systems. A simplified mathematical expression (which is function of the ratio between the fundamental vibration period of the system and that of the soil, ductility demand, and level of asymmetric yielding) is proposed to estimate the amplification factors. The expression is applied successfully to a 9-story reinforced concrete building exhibiting asymmetric yielding produced by tilting.     

Modeling and Seismic Response Analysis of Italian Code-Conforming Reinforced Concrete Buildings

ABSTRACT

This study investigates the seismic response of reinforced concrete buildings designed according to the current Italian building code. Number of stories, site hazard, presence and distribution of masonry infill panels, and type of lateral resisting system are the key investigated parameters. The main issues related to design and modeling are discussed. Two Limit States are considered, namely Global Collapse and Usability-Preventing Damage. The main aim of the study is a comparison between the seismic response of the buildings, investigated through nonlinear static and dynamic analyses. Irregularity in the distribution of infill panels and site hazard emerge as the most influential parameters.     

Masonry Italian Code-Conforming Buildings. Part 1: Case Studies and Design Methods

ABSTRACT

Several architectural configurations of unreinforced masonry residential buildings are designed according to the different methods proposed in the Italian code: rules for the so-called simple masonry buildings, linear and nonlinear static analyses. Always complying with code requirements, for each building-site combination, the design was made, as much as possible, without an excessive margin of safety. The different design methods provided buildings with very different levels of safety, being linear static analysis largely overconservative with respect to the nonlinear static approach. These buildings were then analyzed in the companion paper.     

Efficiency and Cost-Benefit Analysis of Seismic Strengthening Techniques for Old Residential Buildings in Lisbon

This paper presents a study on the techno-economic efficiency of seismic strengthening techniques for old residential buildings, with application to construction typologies in Lisbon (stone masonry and “Placa” buildings). A comprehensive review on strengthening techniques and implications for the seismic behavior is made. Different strengthening schemes are implicitly simulated within equivalent frame models of the representative buildings. Then, pushover analysis is applied in order to compare the seismic performance of the buildings, before and after strengthening. A cost-benefit analysis of the strengthening solutions is finally performed, comparing the economic benefit gained by reducing the seismic damage, against the intervention cost.     

Estimating the Seismic Performance of CFRP-Retrofitted RC Beam-Column Connections Using Fiber-Section Analysis

Over the past two decades, many experimental techniques have been developed to improve the efficiency of the externally-bonded fiber-reinforced polymers (FRPs) in order to improve the structural performance of reinforced concrete (RC) beam-column connections. Numerical analysis is also being used as a cost-effective tool to predict the experimental results and to further investigate the parameters that are beyond the scope and capacity of experimental tests. In this study, at first, a fiber-section modeling approach is developed for estimating the seismic behavior of RC beam-column connections before and after application of FRP retrofits. The accuracy of the analysis results were validated against a series of the available experimental data under both monotonic and cyclic loadings. It was pointed out that the proposed model can predict the strength and displacement of un-retrofitted and FRP-retrofitted RC beam-column connections up to the failure points. The verified model was then used to perform a parametric study pertaining to the effect of longitudinal reinforcement ratio on the efficiency of the adopted FRP retrofitting technique to improve the structural behavior of RC beam-column connections.     

重庆钓鱼城遗址悬空卧佛彩绘颜料初步分析

钓鱼城悬空卧佛造像系创作于晚唐时期的一尊巨型石刻,具有极高的历史、艺术、科学、宗教价值,但造像保存现状较差,存在颜料脱落、酥碱粉化、起甲等病害,亟待保护修复。为了解悬空卧佛彩绘颜料层的成分与结构,采用金相显微镜、拉曼光谱、X射线荧光(XRF)、X射线衍射(XRD)、扫描电镜-能谱仪(SEM-EDS)等多种现代方法与技术对彩绘样品进行了分析。结果表明:所用红色颜料为铁红、铅丹;蓝色颜料为群青;绿色颜料为碱式氯化铜;青色颜料为墨绿砷铜矿;白色颜料为硫酸铅;局部有贴金。结果还表明,该造像历史上曾多次重绘。本研究成果以期填补钓鱼城悬空卧佛研究的空白,同时为修复工作的开展提供科学依据。     

The application and misapplication of mass analysis in lithic debitage studies

The technique of debitage mass analysis based upon size grades of debitage populations is shown to be prone to errors when making interpretations about the kind of tool produced or the kind of lithic reduction technology used. Significant sources of error may originate from differences in individual flintknapping styles and techniques, raw material size and shape variants, and mixing of debitage from more than one reduction episode. These sources of error render debitage Mass Analysis ineffective for determining the kind of stone tool reduction activities practiced at excavated sites. Mass Analysis may be effective for determining artifact reduction sequences if it is used on debitage from a single reduction episode or part of a reduction episode. However, it is shown that Mass Analysis when used for assessing reduction sequence information, must also control for the effects of raw material variability, assemblage mixing, and flintknapping styles.