Modeling the Cyclic Flexural and Shear Response of the R. C. Hollow Box Columns of an Existing Viaduct

The cyclic response of R.C. hollow box columns, constructed as part of a typical single-column bent viaduct, built in the 1970’s in Central Europe, was studied both experimentally and analytically. Moderate displacement ductility capacity (between 3 and 4) was observed regardless of the column construction details, which are nowadays considered inappropriate for seismic regions. Standard analytical flexural models correlated with the experimental results quite well. Shear strength was estimated using the two methods included in the EC8 standards, as well as the method developed at the University of California, San Diego. Quite different results were obtained. The most accurate was the third method.     

上海博物馆明清家具接榫修复及其力学原理

榫卯结构是中国古代木构家具的核心。由于古木家具的材料易朽烂和吸湿膨胀等缺陷,且节点几何形式多样,使节点处于复杂的应力状态,导致榫卯容易拔出或断损。针对此类问题,首先在对上海博物馆收藏的明清家具展开调查研究的基础上,分析了馆藏古木家具的破坏形式,并提出了以接榫为主的修复方案;其次利用连续介质力学的理论分析、数值模拟和性能试验,阐述了接榫修复的力学机理,验证了原有修复方案的科学性与正确性;最后,依据力学模型对馆内已有的修复方案进行了优化。     

“平均地权”本义的由来与演变——孙中山“民生主义”再研究之二

"平均地权"是孙中山"民生主义"的内容之一.其最初理路是土地国有与耕者有其田.后来演变为核定地价、涨价归公,再变为定价收买,并重申耕者有其田的主张.其目的是要使农民成为具有独立经济地位和独立人格的自耕农,随着农村经济的发展,形成农村中的中产阶级.     

福建莆田元妙观三清殿及山门彩绘的保护

介绍了福建莆田元妙观三清殿及山门彩绘的风格、价值和保存现状,对保护方法进行了探索,通过实验选择了理想的加固材料,建立了完整的保护档案,培训了一批保护人才,为我国古建彩绘的保护积累了经验。     

通古斯巴西古城遗址土体特性及PS加固试验

通古斯巴西古城遗址是新疆重要的土遗址之一,原为唐龟兹驻兵的安西都护府所在地。遗址中曾出土大批文物,对于研究西域的屯垦历史和古代城址布局等有重大意义。为了系统地研究了通古斯巴西古城遗址土的工程特性,在实地调查的基础上,通过室内试验对通古斯巴西古城遗址土的物理、力学、水理和化学性能进行测试。此外,还测定了不同PS浓度加固后遗址土重塑土块抵抗风蚀雨蚀能力的差异,进一步确定了PS的渗透加固措施对土质文物的防风化及雨蚀效果。结果表明,7%的PS溶液防风化抗雨蚀效果要更为显著。研究结果可为PS的施工应用提供依据。     

Technical microwear and residues in identifying bipolar knapping on an anvil: experimental data

The functional study of the stone tool artefacts from the Middle Pleistocene site of Isernia la Pineta (Molise, central Italy) revealed microtraces that display certain features that did not fit in with what we know as use-wear traces. The suspicion that these microtraces may be technical traces derived from bipolar flaking, which is prevalent at this site, led us to initiate an experimental programme to check our hypothesis. The experiments conducted allowed us to identify residues associated with bipolar flaking on an anvil and to characterise the microscopic traces derived from this production technique. Our results proved very useful in identifying the artefacts produced by bipolar flaking, as well as in determining the basic lithological features of the anvil. Moreover, these experiments allowed us to assess the possible interferences that these kinds of technical traces can cause when performing the functional analyses of lithic assemblages produced by the bipolar technique.     

Measuring Museum Visitor Preferences Towards Opportunities for Developing Social Capital: An Application of a Choice Experiment to the Discovery Museum

This study investigates preferences of visitors to the Discovery Museum (in North East England) with respect to opportunities to develop social capital. The extent to which museums generate social capital is largely unknown, but museums have potential opportunities to develop this type of capital. This study uses a stated preference choice experiment (CE) technique to estimate museum visitor preferences towards social capital opportunities. The findings indicate that visitors have a preference for visiting a museum with another individual(s); and that the provision of participatory activities, extended opening hours and locally related displays would generate more social capital among visitors and in society.     

Seismic Evaluation and Retrofit of Asymmetric Multi-Story Wood-Frame Building

The presented research focuses on large-scale seismic testing under multi-directional ground motion of a three-story high, wood-frame residential building representing late 1960's California construction. Earthquake lateral resistance is provided by plywood shear walls around the perimeter of the building with an open front in the first story for tuck-under parking. Accordingly, the as-built structural configuration is asymmetric in plan and discontinuous in elevation with tendency to twist about a vertical axis and to form a weak story mechanism. The test results confirm this tendency. They also reveal the sensitivity of the response to multi-direction ground motion. Asymmetric damage patterns are induced by the multi-component motions in the walls oriented perpendicular to the open front for the as-built test structure, with or without finish materials. However, the observed damage remained noncritical as far as structural integrity is concerned even for ground accelerations exceeding 120% of that recorded during Northridge earthquake. This is viewed as a consequence of the better construction of the test building compared to actual construction. Investigated retrofit includes adding a welded moment resisting steel frame around of the garage opening and strengthening the diaphragm to header beam connections. The study indicates that the retrofit significantly reduced the maximum story drift in the open front. Moreover, the finish material and the retrofit greatly reduce the maximum rotation of the building about the vertical axis.     

Levallois economics: an examination of ‘waste’ production in experimentally produced Levallois reduction sequences

Mathematical modelling has suggested that Levallois core morphology represents a reduction strategy driven by economic considerations; particularly the minimization of ‘waste’ while aiming to maximize cutting edge length of flakes obtained from cores of a given size. Such models are elegant in that they facilitate formal modelling of economic considerations that potentially motivate patterns seen in prehistoric data. However, the abstract nature of such models means that they do not take full account of all the practical difficulties and material challenges involved in reproducing Levallois-style reductions in stone. In particular, such models have only examined nodule morphology in two-dimensions, and did not take account of the fact that in the case of classic (lineal) Levallois reduction, core surfaces must be re-prepared between successive stages of flake removal. Hence, the potential economic implications of these factors are currently unknown, potentially undermining the significance of models that assume specific economic conditions. Here, we undertook to examine these factors using a series of experimentally produced Levallois reduction sequences. A total of 3957 flaking events were considered in our analyses, and we used six specific measures of economy to examine Levallois reduction across successive phases. Our analyses found that key assumptions of mathematical models suggesting that Levallois core morphology was driven by economic considerations (i.e. conservation of raw material when attempting to remove flakes with long cutting edges) can be upheld under the practical challenges of replicating Levallois-style reduction in stone. In supporting the notion that Levallois reduction has advantageous economic properties, our results emphasize the importance of considering why Levallois reduction did not emerge earlier in the archaeological record, and indeed, why even during the later Pleistocene the temporal and geographic distribution of Levallois technology varies. Our results also re-emphasize the value of formally modelling lithic reduction strategies in specific economic terms.     

Das Problem der “entscheidenden Experimente”

In this historical essay an attempt is made to discuss the problem of decisive experiments both from the point of view of History of Science and of Philosophy of Science. The first part deals with Francis Bacon's idea of instantiae crucis and with the use of the term experimentum crucis mainly in optics. With respect to the experimental confirmation of Maxwell's electrodynamics the Duhem-Quine Thesis is discussed. Duhem had argued that not a single hypothesis but only a complete theory is examined by experiment. So a single experiment neither can prove nor can disprove a single hypothesis. With regard to Bucherer's and Neumann's data concerning the velocity-dependence of the electron's mass the question of the certainty of conclusions arising from experimental tests is treated. In the last parts the really historical problem of the decisive experiments is considered, namely the gap between the context of design of an experiment and the context of evaluation of an experiment in retrospect. The examples here are the Michelson-Morley experiment, the Franck-Hertz experiment, and the Compton-Effect. In the conclusion parity violation is discussed. Perhaps due to the possibility of a single alternative in theory and an unambiguous result of the experiment this test really was crucial. In general, however, the experimentum crucis will prove to be a very seldom event.