慈利白公城遗址出土木材种属的鉴定研究

慈利白公城遗址历史悠久,具有重要的考古价值。该遗址出土了大量木质井壁及少量其他木质文物,为了解这些木材的特点,以及为木材保护提供相关的参考,通过徒手切片,并利用光学显微镜对该遗址出土的10件木质样品进行鉴定。结果表明其中1件为无患子(Sapindus. mukorossi Gaertn.),1件为冷杉(Abies fabri(Mast.)Craib),2件为湖南杨桐(Adinandra. acutifolia Hand.-Mazz.),2件为香椿(Toona sinensis A. Juss.),4件为润楠(Machilus pingii Cheng ex Yang)。通过实验结果,初步推测井壁的制作在当时是比较重要的工作,此时已经在选择性地使用木质井壁原料。从树种适宜生长的环境上看,同时期该遗址附近可能是以阔叶材为主的针阔叶混交林,气候温暖湿润。     

甘肃酒泉、嘉峪关壁画墓霉菌分离鉴定与防治研究

通过对墓葬壁画霉菌分离鉴定,筛选出合适的防霉材料,对壁画进行防霉处理是解决未搬迁尚很潮湿壁画墓科学保存问题的一个重要方面。     

A High-Performance Quadrilateral Flat Shell Element for Seismic Collapse Simulation of Tall Buildings and Its Implementation in OpenSees

Shear walls are important lateral force-resistant components of tall buildings. Hence, a reliable numerical model that can accurately represent the mechanical characteristics and large deformations of shear walls is critical for realistic collapse simulation of tall buildings. Based on the theory of generalized conforming element, a high-performance quadrilateral flat shell element, NLDKGQ, accounting for the large deformation using the updated Lagrangian formulation, is proposed herein and implemented in OpenSees. The reliability of NLDKGQ is validated using classical benchmark problems and reinforced concrete specimens. In addition, its capability in simulating the collapse of a tall building is also demonstrated.     

The Numerical Study of Base-Isolated Buildings Under Near-Field and Far-Field Earthquakes

The behavior of base-isolated building frame is investigated with the help of a numerical study for far-field and near-field earthquakes with directivity and fling-step effects. Both design-level and extreme-level earthquakes are considered. Selected response parameters are peak floor displacement, acceleration, base shear, and isolator displacement. Inelastic behavior of base-isolated structure during the earthquake is investigated performing nonlinear time history analysis of a ten-story building frame. This study shows that base isolation is not effective for near-field earthquakes. Even for design-level earthquake, the frame gets significantly into inelastic range for earthquakes with fling-step effect.     

Seismic Damage Reduction of a Structural System based on Nontraditional Sliding Interfaces with Graphite Lubrication

In this paper, we propose a free-standing structure that is unanchored to its foundation and has a cost-efficient interface consisting of common construction materials (steel, mortar, and iron) with graphite lubrication; this structure is expected to behave as an earthquake-resistant structure during small earthquakes and a base-isolated structure during large earthquakes. To realize the structure, this study examined the frictions of the interfaces in shaking table tests. In addition, the seismic responses of the free-standing structures based on the interfaces were examined via incremental dynamic analyses with 44 ground motions and a simple model of typical Japanese steel structures.     

多种科技方法在古月桥勘察修缮设计中的应用

建于南宋嘉定六年(公元1213年),位于浙江省义乌市的古月桥是折边拱桥这种桥梁发展过渡形式中不可多见的典型实证,具有极高的历史、科学、艺术、文化和社会价值。为了明确古月桥目前的状态,分析其主要威胁及病害原因,判断结构稳定性,进而制定有针对性的修缮方案,采用多种科技方法对古月桥进行了勘察和综合判断。面对桥身残破的现状,工作组采取了三维激光扫描、微观实验、结构分析等多种科技方法综合勘察,不仅较为清晰的地了解了古月桥的病害威胁,也分析了其背后致因及相互之间的联系;最终对古月桥稳定性及保存状况做出了综合判断。上述多种方法的应用,不仅相互印证了勘察结论,也为后续保护工作提供了重要的依据。     

Raspadita: a new lithic tool from the Isthmus of Rivas,Nicaragua

A new lithic tool type was discovered at the Pacific Nicaraguan archaeological site of Santa Isabel (AD 800–1350) and named raspadita (small scraper). Thousands of these small tools (1–2 cm in length) were found. They have a rounded proximal edge and a pointed distal end. In this study, the raspaditas are proved to be a coherent tool class with minimal variation in size, shape, material type and usewear. They were manufactured from white chert bladelet cores using soft hammer percussion and pressure flaking unifacial retouch. Usewear points to a composite tool form and a scraping function for the raspaditas. Scanning electron microscopy determined a ventral leading, dorsal following, unidirectional scraping motion for the raspadita proximal end. The material that was scraped has still to be definitely determined but phytoliths visible in the SEM images suggest that the composite tool was used for plant processing.     

清代垦殖政策与陕北长城外的生态环境

陕北长城外地区位于蒙陕农牧交错带,属于典型的脆弱生境地带。清代中央和地方两级政府针对当地汉民承租蒙民土地从事农牧业生产这一环节,在不同时期制定了不同的垦殖政策,经历了封禁、招垦、禁垦、拓垦四个阶段,这既是清政府对陕北长城外地区逐步认识和开发的过程,同时也是该地区生态环境变化的过程。在政策—人—环境相互作用的关系过程中,制度、政策与权力的结合对区域环境变化的影响具有根本性的驱动作用。     

Development of Collaborative Structure Analysis (CSA) System and Its Application to Investigate Effects of Soil-Structure Interaction

In this article, a collaborative structure analysis (CSA) system is developed for integrating different finite-element simulation programs. In this system, a simulated structure is divided into multiple substructures, and the interaction between the substructures is considered. Interfaces for the commercial finite-element program ABAQUS and for an open-source framework for structure analysis, OpenSees, are developed to achieve CSA integration. The CSA system is applied to analysis of a soil-structure interaction (SSI) problem, and the effects of SSI are investigated, and the efficiency and accuracy of the system are demonstrated.     

中国古文献中所看到的古代建筑结构力学认识研究

考察古代人的结构力学认识,是对古建筑结构的分析及解释必不可少的研究之一。因为与现代建筑结构不同,古代建筑结构主要取决于当时工匠们的经验与直观判断。古代人对结构力学的认识概念,我们从中国古文献中可以看到。通过本研究发现,古代人已经有对力与荷重的力学认识以及古建筑的对称结构就是从古代力学的平衡概念出发而发展的。