Dynamical Assessment of the Work Conditions of Reinforcement Tie-Rods in Historical Masonry Structures

Tie-rods are essential structural elements, which have been employed for centuries in masonry historical buildings, either during the construction or in successive strengthening interventions, with the aim of containing dangerous horizontal actions. The actual work conditions of these tie-rods, which are strongly influenced by their load history, are difficult to be quantified theoretically, and an effective method for their measure is of great importance in order to ensure the efficiency of these elements during the time and the stability of the entire building. Common measurements are often carried out adopting models based upon significant simplifications, like, for example, hinges at the extremities. These assumptions, rarely represent the real work conditions for anchorages. In this work, a non-destructive testing method is presented, based upon sophisticated dynamical models that can take into consideration many of the circumstances neglected by the simplified models. Four case studies are extensively described, trying to embrace the most common situations in term of peculiar features of the building, structural configuration, and load history. The discussion of the results yields the safety margin of the rod with respect to the material failure and provides important indications about the overall stability of the whole building.     

‘Why did they take him away?’ The theft of Neddy Larkin

Neddy Larkin, a Bundjalung man from New South Wales, Australia, was stolen from his grave and in 1891 sold to the Peabody Museum, Cambridge, MA. This paper uses the methodology and concepts outlined in Latour’s An Inquiry into Modes of Existence to chart Neddy Larkin’s transitions from kinsman to scientific data.     

Paving the way for new regional industrial paths: actors and modes of change in Scania’s games industry

ABSTRACT

Recent scholarly work has enhanced our understanding of how new path development activities are enabled or constrained by ‘regional environments’, made up of pre-existing industrial structures, knowledge organizations, support structures and institutional configurations. This paper moves beyond overly static views on regional environments. We develop a dynamic perspective by analysing conceptually and empirically how a constraining environment can be transformed into one that enables the development of new growth paths. The paper offers a typology of various modes of change, including layering, adaptation and novel application that are used by key actors to ‘manipulate’ the regional support structures to facilitate new regional industrial path development. The conceptual framework is applied to a case study of the digital games industry in the region of Scania, southern Sweden. Our findings suggest that the creation of a more enabling environment for the growth of the digital games industry has been the outcome of multi-scalar processes and combinations of various modes of change employed by a few key individuals operating in the newly emerging path.     

SEISMIC RESPONSE CONTROL OF CABLE-STAYED BRIDGE USING DIFFERENT CONTROL STRATEGIES

The goal of this research is to study the effect of cable vibration through a number of control cases of a cable-stayed bridge. In order to consider the complicated dynamic behaviour of the full-scale bridge, a three-dimensional numerical model of the MATLAB-based analysis tool has been developed by the complete simulation of the Gi-Lu bridge. The dynamic characteristics of cables in the cable-stayed bridge are verified between the field experiment and the result from numerical simulation using geometrically nonlinear beam elements in MATLAB program. Three types of control devices are selected to reduce the response of the bridge deck which includes: actuators, viscous-elastic dampers with large capacity, and base isolations. Moreover, two types of control devices, MR dampers and viscous dampers, are installed either between the deck and cables and/or between two neighbouring cables for controlling the cable vibration. A modified bi-viscous model combined with convergent rules is used to describe the behaviour of MR dampers. Finally, through evaluation criteria the control effectiveness on the cable-stayed bridge using different control strategies is examined.     

Mine blast vibration response spectrum for structural vulnerability assessment: case study of heritage masonry buildings

Ground-borne vibrations induced by mine blasting are typically of low amplitudes, which are not considered a major concern for modern engineered structures. However, historic structures are often considered more vulnerable due to inadequate knowledge regarding the state of construction materials and structural response. Specifically, the construction materials used might be fragile or have deteriorated to a stage that could be vulnerable to such vibrations. Simplistic rule based on peak ground motion parameter has been adopted worldwide for safety assessment, while the frequency characteristics of vibrations are not taken into account. Further, there is very limited study on response of heritage structures to near-field blasting. This article presents a practical structural vulnerability assessment method for mine blast-induced vibrations. In particular, a design response spectrum model is proposed based on close range measurements of nearby mine blasting, which is compared with an existing design spectrum model for far-field mine blasts and a typical design spectrum model for earthquake actions. The method is illustrated through a case study of heritage masonry buildings in Australia. The unique blast data presented and the generalized methodology would be useful to both structural engineers and blast engineers in considering potential effects of blasting on heritage structures.     

Application of Particle Motion Technique to Structural Modal Identification of Heritage Buildings

Determining the behavior of a structure estimated by means of finite elements analysis requires not only an in-depth knowledge of its geometry and dynamic properties but also an experimental validation to corroborate the adequacy of the characteristics of the structure. Most of the current structural identification techniques are based on linear methods that call for many measurement points and/or a relative simple structure. Complex structures are somewhat still an unexplored field due to the difficulties with the finite element method and the experimental corroboration of its results. This study presents the use of particle motion computation applied to each structural vibration mode to improve the identification of its dynamic properties, and its application to the Gothic Cathedral of Palma de Majorca (Spain).     

公平和效率抉择的演进与和谐社会的构建

公平和效率是相互作用、相互依存的,两者的地位和作用随着时代的发展而发生变化。对效率与公平如何进行抉择必须充分考虑到历史的、政治的、思想的因素,中国特色社会主义就是在公平优先、兼顾效率到效率优先、兼顾公平再到公平与效率并重的模式选择中渐进发展的。     

市内激励源对古建筑振动的影响

为了分析在不同激励下振动对古建筑的影响,选择苏州市省级文物保护单位——玉涵堂古建筑进行振动测试。记录了环境振动、地下轨道交通激励、人群社会活动激励和音响激励四种工况时一座两层砖木阁楼的振动信号。发现经过严格振动控制的地下轨道交通激励对古建筑振动的贡献可以忽略;环境振动和音响激励时段古建筑横向振动速度达标,而人群社会活动激励时段横向振动速度超标。从古建筑的建筑结构和功能区域划分以及人的激励形式三个方面对通常被忽视的人的因素进行了探讨,并提出了相应的减振措施。研究成果为其它类似两层砖木阁楼古建筑防护提供依据。     

降雨对榆阳区明长城单体建筑破坏模式的试验研究

前期调查分析可知,降雨对榆阳区明长城单体建筑的破坏形式包括水力侵蚀和重力侵蚀两大类,主要影响因素为降雨特征、遗址保存形态和遗址土的性质。为了进一步了解降雨对该类土遗址的破坏方式及主要影响因素作用特点,按照相似理论要求设计模型试验,研究了降雨对榆阳区明长城单体建筑的破坏模式。试验结果表明,降雨对遗址模型的破坏方式与前期调查分析结果基本一致,水力侵蚀方式有冲沟侵蚀、片流面蚀、流水淘蚀和流水冲蚀,重力侵蚀方式有坍塌和滑塌。一般A型暴雨条件下,各种水力侵蚀方式均有发生,重力侵蚀发生次数相对较少;B型暴雨条件下,主要发生片流面蚀,重力侵蚀破坏发生次数较多。通过模型试验得出的降雨对遗址模型的破坏方式及发生特点方面的结论,可以在一定程度上为降雨对该类遗址破坏的评估和防治提供参考。     

东北地区农业产业化发展路径与地域发展模式研究

文章阐述了东北地区农业产业化发展的背景条件,分析了发展农业产业化所取得的成就和存在的主要问题;依据劳动地域分工理论和东北地区农业发展的自身优势、产业基础和在全国农业生产中的地位和作用,提出了东北老工业基地农业产业化的发展路径和地域发展模式。