SOIL-STRUCTURE AND SOIL-STRUCTURE-SOIL INTERACTION: EXPERIMENTAL EVIDENCE AT THE VOLVI TEST SITE

This paper shows the results of two passive experiments carried out at the European Volvi test site where a scaled building has been constructed. The first experiment was performed to study the motion of the structure excited by two small earthquakes. For one month, six strong-motion recorders were installed within the structure, at the top and at the basement. The analysis of the deformation of the structure has been assessed by computing the spectral ratio between the top and the bottom, with a special focus on soil-structure interaction. An analytical model was then proposed to reproduce the structure and soil-structure system behaviour. The soil-structure interaction was accounted for by using impedance functions. During the second experiment, we concentrated our efforts on the effect of the building vibration on the surface ground motion. An explosive shot was fired and several strong-motion recorders were installed on the ground close to the structure that allowed us to clearly identify a monochromatic wave coming from the building, in the time and frequency domains. This experiment allows us to demonstrate the non-negligible effect of the soil-structure-soil interaction that may disturb the surrounding ground motion.     

COUPLED P-Y T-Z ANALYSIS OF SINGLE PILES IN COHESIONLESS SOIL UNDER VERTICAL AND/OR HORIZONTAL GROUND MOTION

Various approaches are currently used for the analysis of piles under vertical and lateral loading. Among these, the beam-on-a-nonlinear Winkler foundation (BNWF) approach using published P-y, T-z and Q-z curves is widely used in practice. In this approach, the P-y and T-z responses are generally uncoupled from each other. The objective of this paper is to investigate the influence that the coupling of the P-y and T-z responses has.on the cyclic and dynamic response of piles in cohesionless soil. A cyclic model is first developed and a parametric study is conducted to investigate the effect the initial confining pressure, angle of wall friction and effective vertical stiffness have on the lateral cyclic hysteretic response. A dynamic model is then developed, and used to study the response of a single pile in cohesionless soil under horizontal and/or vertical ground motion. Results from the parametric study showed that the three parameters did not have a significant influence on the lateral cyclic hysteretic response. Under horizontal and/or vertical ground motion, the horizontal ground motion was observed to dominate the inertial interaction response, and significantly affected both the horizontal and vertical displacement response, mainly due to second-order P-Δ and gapping effects.     

SEISMIC SOIL-STRUCTURE INTERACTION: BENEFICIAL OR DETRIMENTAL?

The role of soil-structure interaction (SSI) in the seismic response of structures is reex-plored using recorded motions and theoretical considerations. Firstly, the way current seismic provisions treat SSI effects is briefly discussed. The idealised design spectra of the codes along with the increased fundamental period and effective damping due to SSI lead invariably to reduced forces in the structure. Reality, however, often differs from this view. It is shown that, in certain seismic and soil environments, an increase in the fundamental natural period of a moderately flexible structure due to SSI may have a detrimental effect on the imposed seismic demand. Secondly, a widely used structural model for assessing SSI effects on inelastic bridge piers is examined. Using theoretical arguments and rigorous numerical analyses it is shown that indiscriminate use of ductility concepts and geometric relations may lead to erroneous conclusions in the assessment of seismic performance. Numerical examples are presented which highlight critical issues of the problem.     

MODELLING OF NONLINEAR DYNAMIC BEHAVIOUR OF A SHALLOW STRIP FOUNDATION WITH MACRO-ELEMENT

A new nonlinear soil-structure interaction macroelement is presented. It models the dynamic behaviour of a shallow strip foundation under seismic action. Based on sub-structured methods, it takes into account the dynamic elastic effect of the infinite far field, and the material and geometrical nonlinear behaviour produced in the near field of the foundation. Effects of soil yielding below the foundation as well as uplift at the interface are considered. Through the concept of macro-element, the overall elastic and plastic behaviour in the soil and at the interface is reduced to its action on the foundation. The macro-element consists of a non linear joint element, expressed in the three degrees of freedom of the strip foundation, reflecting the limited bearing capacity of the foundation. This model provides a practical and efficient tool to study the seismic response of a structure in interaction with the surrounding soil medium. Applications to a bridge pier show the potentialities of this kind of model.     

EFFECT OF SOIL-STRUCTURE INTERACTION ON SEISMICALLY ISOLATED BRIDGES

The objective of this study is two-fold: first, to assess the effects of soil-structure interaction (SSI) on the response of seismically isolated bridge piers and, second, to develop a method that considers SSI and can be easily applied to the preliminary design of bridges. Emphasis is given on pier behaviour, because piers together with the abutments are the most critical components of a bridge with a high potential for concentration of ductility demands during earthquakes. The relative importance that several parameters of the bridge-isolators-soil system play on design is examined. Conclusions and suggestions that can lead to safer and more economical isolated pier design are also presented. Cases in which SSI needs to be incorporated in seismically isolated bridge design are identified and ways to take advantage of SSI in order to enhance safety level and reduce design costs are recommended.     

ORGANIZATION,LEGITIMATION, PARTICIPATION

This article suggests a new interpretation of the state formation process in Early Modern Sweden, focusing on three dimensions: The organization of the state as a way to use limited resources in a rational way, the legitimation of rulers in terms of beliefs and values current in society, and the participation of the subjects in state activities. Our model focuses on institutional change as a result of the intensity of interaction between rulers and subjects. Based on our own research, claims are made for new understanding of state formation in Europe that allows more room for political action from below.     

Varied visions: an iconographic reevaluation of Ramey Incised production and distribution in the American Bottom,Illinois

ABSTRACT

Ramey Incised ceramics, characterized by incised symbolic motifs, are often viewed as a hallmark of Stirling-phase Cahokia and the surrounding American Bottom region. However, few comprehensive analyses of the regional Ramey motif assemblage have been conducted. Here I evaluate spatial and temporal variation in Ramey Incised motifs across 16 sites in the American Bottom to improve understandings of Ramey Incised production and distribution. Stirling-phase motif data indicate that the Ramey Incised manufacturing process likely was not as centralized as previously proposed. A qualitative analysis of the regional motif assemblage uncovers variation that may reflect stylistic experimentation. Additionally, motif frequency distributions reveal potential site-specific thematic preferences. Both findings support the existence of local production within the region. Diachronic data suggest the collapse of the Ramey Incised tradition in the Moorehead phase, perhaps in response to sociopolitical and religious transitions occurring at Cahokia. Overall, Ramey Incised ceramics may have served as vehicles through which American Bottom Mississippians variably expressed their interpretations of and relationships to the cosmos.     

城市混居地段外来人口社会隔离的空间测度——以广州客村为例

本研究选取广州客村代表典型的城市混居地段,创新性地从空间维度测度本地人与外来人群体的社会隔离程度,包括其社交对象的地域分布差异及空间活动轨迹的差异。基于社会学二模网络理论,建立空间共场性的概念,测度两类人群的社会隔离程度。研究发现:客村外来人群体的社交对象具有鲜明的迁出地指向特征;本地人与外来人两类群体的空间活动轨迹呈现显著分异,体现为使用公共服务设施与公共开敞空间的区隔;通过两类群体之间及各自内部的共场度测度,发现外来人群体过于离散的空间活动轨迹不利于其获取社会网络的支持。     

In Praise of the Ordinary Man: Popular Media,Social Hierarchy and Identity in a North Indian Text

This article recounts a story found in a popular genre of religious literature known as vrat katha[ritual storytelling]. The narrative is of an “ordinary” low-caste man and his everyday struggles. It tells of the social and economic suffering experienced by the poor man upon encountering god (called Trilokinath/Vishnu) and receiving his blessing, mediated through a series of miraculous events. However, the transformative power of the events and fortunes that follow is undermined by a Brahmin who refuses to acknowledge the poor devotee, rebuffing his ritual gift [prasad] as polluted and considering him untouchable. The ambiguous nature of the gift and the ideology and practice of devotion [Bhakti] present an intriguing and complex picture of Hinduism, revealed in the multiple social roles and social contexts in which subalterns operate in the course of their day-to-day lives.

?I offer a critical reading of this fascinating story. What seems like a straightforward, standardised ritual text is analysed in terms of its competing and sometimes subversive views of “dominant” Hinduism. By examining the tensions and ambivalence in the text I argue for a more nuanced rendition of subaltern power and agency which cannot be reduced to that of resistance and opposition alone.     

谈士山盘铭文的“服”字义

本文从唐兰先生旧说出发,讨论新见士山盘铭文“服”字含义,认为其相当于《左传》、《国语》中所见的“职贡”一词,具体包括职事与贡赋两个方面。另外提出士山盘铭之方国“履”应即金文所见的“眉敖”之“眉”。最后指出士山盘铭对于探讨西周恭王时期的政治和先秦服制都具有重要意义。