Sensitivity Analysis for Soil-Structure Interaction Phenomenon Using Stochastic Approach

This article analyses 1.36 million realistic soil-structure interaction (SSI) scenarios in a systematic fashion to define the correlation between soil, structural, and system parameters and interaction effects on the structural response. In the analyses, a soil-shallow foundation-structure model that satisfies design building code requirements is utilized. It has been identified that soil shear wave velocity, shear wave velocity degradation ratio, structure-to-soil stiffness ratio, and structural aspect ratio combined with the system stiffness are the key parameters whose variation significantly affects variation in structural response. The critical range of variation of these parameters resulting in a detrimental SSI effects is also defined.     

Statistical Characterization of Structural Demand under Earthquake Loading. Part 2: Robust Estimation of the Dispersion of the Data

Performance-based earthquake engineering methodologies often require a probabilistic model of structural demand. Since observations masking the probability distribution of the majority of the data are frequently found, robust estimation methods are proposed to estimate the probabilistic model parameters (i.e., central value and dispersion). The performance of thirty-three robust dispersion estimators is evaluated, for different sample sizes, using the chord rotation, curvature, shear force, and inter-story drift demands obtained after analyzing five reinforced concrete structures under real earthquake records scaled to several intensities. Based on the results, combinations involving dispersion and central value (defined in a companion article) estimators are proposed.     

Direct Acceleration Feedback Control of Shake Tables with Force Stabilization

This study presents a new strategy for shake table control that uses direct acceleration feedback without need for displacement feedback. To ensure stability against table drift, force feedback is incorporated. The proposed control strategy was experimentally validated using the shake table at the Johns Hopkins University. Experimental results showed that the proposed control strategy produced more accurate acceleration tracking than conventional displacement-controlled strategies. This article provides the control architecture, details of the controller design, and experimental results. Furthermore, the impact of input errors in shake table testing on the structural response is also discussed.     

Effect of Nonlinearity of Frame Buildings on Peak Horizontal Floor Acceleration

Using representative numerical models of eight code-designed steel moment-resisting frame buildings and several ground motions, time-history analyses are performed and a critical evaluation of Peak Horizontal Floor Acceleration (PHFA) demands is conducted. The frames are modeled alternatively as linear and nonlinear systems to isolate the effect of building nonlinearity on PHFA. In most cases, PHFA is reduced when nonlinear behavior of a building is considered; however, in some cases, significant amplification of PHFA is observed. Results from the numerical study provide insight into the trend of modal response modification factors presented taking ground motion spectral shape into account.     

Review of Different Pushover Analysis Methods Applied to Masonry Buildings and Comparison with Nonlinear Dynamic Analysis

This article presents the comparison among different nonlinear seismic analysis methods applied to masonry buildings, i.e., pushover analyses with invariant lateral force distributions, adaptive pushover analysis and nonlinear dynamic analysis. The study focuses on the influence of lateral force distribution on the results of the pushover analysis. Two simple benchmark case studies are considered for the purpose of the research, i.e., a four-wall masonry building prototype without floor rigid diaphragms and a two-wall system with a cross-vault. The comparative study offers a useful review of pushover analysis methods for masonry structures and shows advantages and possible limitations of each approach.     

Experimental Study on Seismic Performance of Mechanical/Electrical Equipment with Vibration Isolation Systems

A prototype diesel generator equipped with a vibration isolation system consisting of restrained isolators (denoted as I/system) is quasi-statically and dynamically tested. Sequentially, the seismic simulation tests are conducted to further investigate the effectiveness of additional snubbers incorporated into the vibration isolation system (denoted as I/R system). Comparing the test results to the static design demands specified in ASCE 7-10, the recommended component amplification factor could represent the horizontal acceleration amplification phenomenon of the generator equipped with I/R system; however, the seismic force demands for static design of I/R system might not be appropriate and conservative enough.     

Unusual Overshooting in Steady-state Response for Structure-dependent Integration Methods

It is numerically illustrated that an unusual overshooting phenomenon might occur in the solution of a forced vibration response if a structure-dependent integration method is applied to conduct the analysis, such as Chang explicit method [2002] and CR explicit method [2008]. This overshooting may occur in the steady-state response of a high frequency mode and it becomes significant as the natural frequency of the mode increases. This unusual overshooting behavior can be successfully detected by using a local truncation error derived from a forced vibration response rather than a free vibration response. A missing loading term in the difference equation for displacement increment is responsible for this unusual overshoot. It is analytically and numerically verified that the unusual overshooting behavior will automatically disappear after introducing the missing loading term into the difference equation for displacement increment.     

田螺山遗址古菱角埋藏环境调查与保护对策的初步研究

本文运用多种化学分析方法分析了浙江省田螺山遗址的地层土壤和地下水环境,得出了不同地层中主要元素的分布规律：再对古菱角外壳遗存和现代菱角外壳进行扫描电镜和元素分析,总结古菱角经长期埋藏后,外壳结构和化学元素的变化规律：最后初步探索古菱角类植物遗存的科技保护时策。     

浙江越窑青瓷标本信息数据库管理系统的设计与实施

对文物标本进行系统分析归纳是传统工艺研究的必要途径,为实现越窑青瓷标本资料的资源共享,提高实验室工作效率,实现分析数据的科学管理,本研究开发设计了“浙江越窑青瓷标本信息数据库管理系统”.该系统基于B/S结构模式,以浙江省博物馆陶瓷标本中心的各类越窑瓷片标本来源、形态、化学成分、物理性能、显微结构、制作工艺等相关信息数据为基础,采用Wi ndows平台,以Visual Studi0 2010为开发环境,结合ASP.NET 4.0框架以及SQL Server数据库技术而构架.经过系统测试和实际运行证明,此管理系统具有良好的应用界面,交互性强,运行稳定,数据处理方便等优势,对实现古陶瓷研究信息资源共享,全面开展越窑青瓷的科学化研究提供了一个良好的数据平台.     

REVISITING PLATFORM MOUNDS AND TOWNHOUSES IN THE CHEROKEE HEARTLAND: A COLLABORATIVE APPROACH

Abstract

This article describes the development and initial results of the Western North Carolina Mounds and Towns Project, a collaborative endeavor initiated by the Tribal Historic Preservation Office of the Eastern Band of Cherokee and the Coweeta Long Term Ecological Research Program at the University of Georgia. The goal of this project is to generate new information about the distribution of late prehistoric mounds and historic period townhouses in western North Carolina. This ongoing research has produced updated location and chronological data for 15 Mississippian period mounds and historic Cherokee townhouses, and led to the discovery of a possible location for the Jasper Allen mound. Using these new data, I suggest that David Hally's model for the territorial size of Mississippian polities provides a useful framework for generating new research questions about social and political change in western North Carolina. I also posit that the cultural practice of rebuilding townhouses in place and on top of Mississippian period platform mounds, a process that Christopher Rodning describes as “emplacement,” was common across western North Carolina. In terms of broader impacts, this project contributes positively to the development of indigenous archaeology in the Cherokee heartland.