Contribution of Earthquake-Resistant Design for Reinforced Concrete Buildings when Coping with External Explosions

Fanaticism, as well as social and economic crises, has provoked a significant increase in the frequency of terrorist attacks during the last two decades and, when considered together with possible accidental explosions, has lead to a higher awareness among involved staff (owners, designers, constructors, government entities). Additionally, the fact that some buildings or targets are in seismic areas while others are not leads to a blast-loading behavior comparison. This article examines the contribution of earthquake-resistant design when coping with ground-surface explosions through nonlinear seismic assessment static analyses and nonlinear time-history analyses of blast resistance assessment using finite elements.     

Impact of Modification on Ground Motion Characteristics and Geotechnical Seismic Analyses for a California Site

The impact of different modification techniques on ground motion characteristics and results of seismic geotechnical analyses is investigated for a site in California. Twenty-eight motions were selected and scaled and also modified using both time domain (TD) and frequency domain (FD) techniques. PGV and PGD of the TD-modified motions are found to be larger than their FD-modified counterparts, but slightly less than the scaled ground motion characteristics. Cyclic stress ratios and amplification factors are similar for all sets of motions. Newmark-type slope displacements caused by the scaled and modified ground motions are similar (within 25%) for a variety of sliding masses.     

Seismic Behavior of L-Shaped RC Squat Walls under Various Lateral Loading Directions

Considerable progress has been made on the research of non-rectangular reinforced concrete (RC) squat walls over the past decades. However, the experimental data of L-shaped RC squat walls remain limited, especially for their seismic behaviors under non-principal bending actions. This paper presents an experimental and numerical investigation on L-shaped RC squat structural walls with an emphasis on how varying the directions of lateral cyclic loading influences the seismic responses of these walls. Four L-shaped specimens are tested under lateral cyclic displacements and low levels of axial compression The variables are axial loads and lateral loading directions. The performance of specimens is discussed in terms of cracking patterns, failure mechanisms, hysteretic responses, deformation components and strain profiles. Furthermore, three-dimensional finite element models are developed to supplement the experimental results. The direction of lateral loading is found to have a significant effect on the peak shear strength of L-shaped RC squat walls.     

《馆藏文物防震规范》关键技术——防震安全设计研究

《馆藏文物防震规范》WW/T 0069-2015,基于馆藏文物防震安全提出馆舍、展陈和文物全系统防震安全理念、设计方法和具体措施。本研究针对馆藏文物防震设计方法、适用范围、展柜及文物安全性判别等关键技术问题展开研究。首先,提出了"地震波+馆舍+展柜+文物"的全过程全系统防震设计理念;其次,针对浮放展柜及文物,进行地震作用下安全性分析研究;第三,与Getty博物馆研究成果对比,验证本研究理论的正确性与可靠性。分析得出:文物防震安全与文物高宽比、支撑接触面摩擦系数、安放处加速度峰值等因素有关;引入了抗滑动安全系数和抗倾覆安全系数进行设计,可充分保证文物安全性。     

潮湿环境模拟考古土遗址夯筑支顶加固效果评估

为研究潮湿环境土遗址加固效果评估方法,在杭州地区进行现场模拟探方加固实验,并对加固后坑壁的波速、含水率、相对水平位移进行监测,对加固的模拟探方稳定性做出评估,以望通过采用科学定量手段评价土遗址夯筑支顶加固效果,为土遗址夯筑支顶加固效果评估提供参考。试验结果表明:模拟探方坑壁表层含水率随深度的增加而升高,含水率变化量逐渐减小;加固后坑壁土体初始强度随深度的增加而提高,且后期硬化过程也较上部区域快,土体强度随时间在逐渐增加;夯筑后坑壁前四五天位移值逐渐增大,且位移值随深度的增加而升高,后期趋于稳定。研究表明,基于变形监测技术评估夯筑体整体稳定性科学合理,基于表层含水量和波速变化评估夯筑土体强度变化是较好的手段。评估结果可为其他潮湿地区土遗址夯筑加固效果评估方法提供参考。     

Excavations on the site of Sir Abraham Elton's glassworks,Cheese Lane,Bristol

SUMMARY: This article examines the evidence for engagement with the rural post-medieval landscape using two national case studies: Wales and Scotland. The issues reflected in these case studies are indicative of the wider challenges for archaeologists and professional practitioners alike. The article recognizes that landscape is not just about geographical place, but an archaeological theoretical framework. It proposes that Post-Medieval Archaeology monographs and conference sessions specific to landscape could help to tease out themes that address the big questions of the post-medieval world — capitalism, modernity and improvement — but also take account of agency, identity and meaning.     

Predictable Achievement Patterns for Student Journals in Introductory Earth Science Courses

Student journals encourage more frequent thinking about course topics, foster development of writing skills, provide feedback about course content and administration, and mitigate exam anxiety. Measures of academic 'ability' and other student characteristics were found to correlate with journal grades. This was unexpected. For example, grades correlated positively with exam scores and GPA, and correlations varied widely among the disciplines represented by the students. Females consistently earned higher journal grades than males. Segmentation modelling (SPSS) identified important subgroups involving gender, age, exam scores and major subject. The journal assignment is, therefore, not equally beneficial for all students.     

SHAPE MEMORY ALLOYS IN SEISMIC RESISTANT DESIGN AND RETROFIT: A CRITICAL REVIEW OF THEIR POTENTIAL AND LIMITATIONS

Shape memory alloys (SMAs) are a class of materials that have unique properties, including Young's modulus-temperature relations, shape memory effects, superelastic effects, and high damping characteristics. These unique properties, which have led to numerous applications in the biomedical and aerospace industries, are currently being evaluated for applications in the area of seismic resistant design and retrofit. This paper provides a critical review of the state-of-the-art in the use of shape memory alloys for applications in seismic resistant design. The paper reviews the general characteristics of shape memory alloys and highlights the factors affecting their properties. A review of current studies show that the superelastic and high-damping characteristics of SMAs result in applications in bridges and buildings that show significant promise. The barriers to the expanded use of SMAs include the high cost, lack of clear understanding of thermo-mechanical processing, dependency of properties on temperature, and difficulty in machining.     

FRAGILITY OF STANDARD INDUSTRIAL STRUCTURES BY A RESPONSE SURFACE BASED METHOD

National and international regulatory standards require industrial risk assessment, taking into account natural hazards including earthquakes, in the framework of Quantitative Risk Analysis (QRA). Seismic fragility analysis of industrial components may be carried out similarly as what has been done for buildings, even though some peculiar aspects require the development of specific tools. In the present paper a contribution to the definition of a rational procedure for seismic vulnerability assessment of standardised industrial constructions in a probabilistic framework is given. The method covers a range of components of the same structural type. Seismic reliability formulation for structures is used. Both seismic capacity and demand are considered probabilistic with the latter assessed by dynamic analyses. The application example refers to shell elephant foot buckling of unanchored sliding tanks. A regression-based method is applied to relate fragility curves to parameters varying in the domain of variables for structural design.     

Physical and Numerical Approaches for the Optimal Insertion of Seismic Viscous Dampers in Shear-Type Structures

This article presents the results of an exhaustive parametric analysis which compares the performances offered by various systems (which lead to both classical and non classical damping matrices) of added viscous dampers in shear-type structures. The aim of the research work here presented is the identification of the system of added viscous dampers which maximizes the dissipative properties under an equal “total size” constraint. The choice of the systems of added viscous dampers considered in the comparison is carried out both using a numerical approach (based upon the use of genetic algorithms) and a physically based approach (based upon the properties of classically damped systems). The comparison is carried out through the numerical evaluation of the dynamic response of representative shear-type structures to both stochastic and recorded earthquake inputs. The results obtained using both approaches indicate that a damping system based upon the mass proportional damping component of the Rayleigh viscous damping matrix (referred to as MPD system) is capable of optimizing simultaneously a number of different performance indexes, providing the best “overall” damping performances. The MPD system is characterised by viscous dampers (a) which connect each floor to a fixed point and (b) which are sized proportionally to the corresponding floor mass.