Risk Assessment and Optimisation of Blast Mitigation Strategies for Design and Strengthening of Built Infrastructure

A probabilistic risk assessment procedure is developed which can predict risks of explosive blast damage to built infrastructure, and when combined with life-cycle cost analysis, the procedure can be used to optimise blast mitigation strategies. The paper focuses on window glazing since this is a load-capacity system which, when subjected to blast loading, has caused significant damage and injury to building occupants. Structural reliability techniques are used to derive blast reliability curves for annealed and toughened glazing subjected to explosive blast for a variety of threat scenarios. The probabilistic analyses include the uncertainties associated with blast modelling, glazing response and glazing failure criteria. Damage risks are calculated for an individual window and for windows in the facade of a multi-storey commercial building. The paper shows an illustrative example of how this information, when combined with risk-based decision-making criteria, can be used to optimise blast mitigation strategies.     

Risk Assessment and Optimisation of Blast Mitigation Strategies for Design and Strengthening of Built Infrastructure

A probabilistic risk assessment procedure is developed which can predict risks of explosive blast damage to built infrastructure, and when combined with life-cycle cost analysis, the procedure can be used to optimise blast mitigation strategies. The paper focuses on window glazing since this is a load-capacity system which, when subjected to blast loading, has caused significant damage and injury to building occupants. Structural reliability techniques are used to derive blast reliability curves for annealed and toughened glazing subjected to explosive blast for a variety of threat scenarios. The probabilistic analyses include the uncertainties associated with blast modelling, glazing response and glazing failure criteria. Damage risks are calculated for an individual window and for windows in the facade of a multi-storey commercial building. The paper shows an illustrative example of how this information, when combined with risk-based decision-making criteria, can be used to optimise blast mitigation strategies.     

Mitigation of Blast Effects on Aluminum Foam Protected Masonry Walls

Terrorist attacks using improvised explosive devices (IED) can result in unreinforced ma-sonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the per-formance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the perform-ance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elas-toplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.     

Mitigation of Blast Effects on Aluminum Foam Protected Masonry Walls

Terrorist attacks using improvised explosive devices (lED) can result in unreinforced masonry (URM) wall collapse.Protecting URM wall from lED attack is very complicated.An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy.However,mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world.In this palaer,numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads.A distinctive model,in which mortar and brick units of masonry are discritized individually,is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model.The aluminum foam is modelled by a nonlinear elastoplastic material model.The material models for masonry,aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads.Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.     

钢筋焊接网技术的特点与应用

钢筋焊接网不仅强度高、施工速度快,而且还能提高工程质量,降低工程综合造价,提高钢筋工程的工业化水平,具有良好的社会效益和经济效益.钢筋焊接网大量应用在房屋的楼板、屋盖、墙体等现浇混凝土结构中.工程实践表明钢筋焊接网是一种值得推广应用的新型、高性能结构材料.     

锚杆技术在泥石流防治工程中的应用与分析

锚杆是一种新型的受拉杆件,用于工程建筑物与地下岩层或土层连接,以承受由于土压力或水压力等其他荷栽所产生的拉力,从而利用地层的“锚固力”,防止建筑结构变形,以维持建筑物或岩层的稳定。锚杆技术在水利水电工程建设中广泛应用,它不仅用于大坝坝基加固,也常用作地下工程的加固及高边坡工程加固的重要手段,可以大幅度减少工程量,应用前景广阔。     

Simplified damage assessment of slab against external blast load

Recently, the mode approximation method (MAM) has been adopted to analyze beam elements against blast load. However, in real cases, the main structural element of an underground structure is slab and side wall since they not only support the structure itself but also may sustain external loads from blast, earthquake, and other kinds of impact. In the present study, the MAM is extended from beam to plate elements and the soil-structure interaction is considered and simplified when calculating structural response under blast load. Pressure-impulse diagrams are generated accordingly for further quick damage assessment.     

Retrofitting of RC Slabs Against Explosive Loads

With the increase of terrorist bomb attacks on buildings, there is a need to develop advanced retrofitting techniques to strengthen structures against blast loads. Currently, several guidelines including an Australian version for retrofitting reinforced concrete (RC) structures are available for the design of retrofitting systems against seismic and monotonic loads using steel or fibre reinforced polymer (FRP) plates that can be either adhesively bonded to the surface or near surface mounted to the concrete cover. However, none of these guidelines provide advice suitable for retrofitting structures subjected to blast loads. In this paper, numerical models are used to simulate the performance of retrofitted RC slabs subjected to blast loads. Airblast pressure distributions on the surface of the slabs estimated in a previous study are used as input in the analysis. A material damage model developed previously for concrete and an elastoplastic model for steel bars are employed in this research for modelling reinforced concrete behaviour due to explosive loads. The material models and blast loading are coded into a finite element computer program LS-DYNA3D to do the analysis. With the numerical model, parametric studies are conducted to investigate RC slabs retrofitted by either externally bonded or near-surface mounted plates or GFRP sheets subjected to blast loads. Discussion is made on the effectiveness of the retrofitting system for RC slabs against blast loads.     

Analysis of structural response under blast loads using the coupled SPH-FEM approach

A numerical model using the coupled smoothed panicle hydrodynamics-finite element method （SPH-FEM） approach is presented for analysis of structures under blast loads. The analyses on two numerical cases, one for free field explosive and the other for structural response under blast loads, are performed to model the whole processes from the propagation of the pressure wave to the response of structures. Based on the simulation, it is concluded that this model can be used for reasonably accurate explosive analysis of structures. The resulting information would be valuable for protecting structures under blast loads.     

交叉双尖窄状多重温室与太阳能热利用

将日光温室进一步改造为内部成交叉双尖窄状的多重温室,使尖窄状内温度更高,从而使置于尖窄状内的太阳能集热器的热效率更高,达90%左右,并将这种特殊结构的温室安装在建筑物窗户外面下端的墙壁上,而热水箱则放于室内,并用软管与集热器相连通,就构成一种窗户型太阳能热利用装置.从而"将多重温室太阳能与建筑相结合,并且使用方式从房顶转向窗户",是一条新的技术路线.     

Development of Light Weight Structures to Provide Blast-Resistant Designs

In the past, blast-resistant designs for structures were often constructed with massive type structural systems, which relied more on brute strength than on finesse to achieve the required blast resistance. However, structures composed of COLD-FORMED steel components, such as sheet metal and metal studs, have shown great promise in providing blast resistance with the added benefits of low cost and ease of construction. Some examples of using such structures to provide containment for package handling facilities (PHF) are described in the paper for situations where blast containment is needed, such as a potential package bomb being discovered during the package vetting process. Results from tests and analytic data are used to illustrate aspects of design peculiar to such types of applications. Designs for specific capacities of PHF are described.     

Numerical method to determine mechanical parameters of engineering design in rock masses

This paper proposes a new continuity model for engineering in rock masses and a new schematic method for reporting the engineering of rock continuity.This method can be used to evaluate the mechanics of every kind of medium;and is a new way to determine the mechanical parameters used in engineering design in rock masses.In the numerical simulation,the experimental parameters of intact rock were combined with the structural properties of field rock.The experimental results for orthogonally-jointed rock are given.The results included the curves of the stress-strain relationship of some rock masses,the curve of the relationship between the dimension △ and the uniaxial pressure-resistant strength σc of these rock masses,and pictures of the destructive procedure of some rock masses in uniaxial or triaxial tests,etc.Application of the method to engineering design in rock masses showed the potential of its application to engineering practice.     

Towards the university of tomorrow: University policy as a consistent system

In this paper the relationship between new technologies and structural changes in society and the economy are discussed. The roles of engineers are described within this revolution of information technology. Through comparing the international patterns of engineering studies, the German model of engineering education is being questioned. It becomes evident that only a consecutive model of higher education studies can be the goal of further university development in Germany. Subsequently, system analysis will be used to draft a new campus structure of the university: the virtual campus consisting of a system of largely independent entities that are linked by different technological and organizational means. Further education needs to be integrated into this virtual campus university. In this way, Germany may serve as an example of how countries around the world are challenged to change fundamentally their educational systems in order to respond to the ongoing revolution in information technology.     

“就业窗口”引导地方工科院校应用物理学专业人才培养模式探讨

随着现代科学的不断进步,地方工科院校也在不断的产生新的学科分支和专业方向,丰富着教育教学体系。地方工科院校应用物理学专业培养的学生主要是把所学的高新技术知识转化为生产力的应用型人才。本文结合当前地方工科院校应用物理学专业面临的实际问题,尝试性地提出以"就业窗口"为引导、以综合性培养为目标的分类式人才培养模式。     

一种伽利略信号跟踪的多路径消除方法

针对伽利略信号调制的特点,提出了一种基于滤波相关器法的多路径消除方法ELSC（early-late strobe correlator）．通过对滤波相关器法应用于伽利略E1信号的跟踪情况进行分析,发现滤波相关器法不能消除延迟为0．5个码片附近的多路径信号影响．ELSC方法通过对几个滤波相关器的叠加,能有效消除0．5个码片附近的多路径信号影响．通过仿真比较了ELSC方法和滤波相关器法对于伽利略信号的多路径误差包络．结果表明ELSC方法优于传统的滤波相关器法,不仅适用于伽利略信号的跟踪,同时也适用于GPS信号的跟踪．     

Use of Advanced Technology Videotapes in the Delivery of Structural Engineering Courses

A teaching and learning development project is currently under way at Queens-land University of Technology to develop advanced technology videotapes for use with the delivery of structural engineering courses. These tapes consist of integrated computer and laboratory simulations of important concepts, and behaviour of structures and their components for a number of structural engineering subjects. They will be used as part of the regular lectures and thus will not only improve the quality of lectures and learning environment, but also will be able to replace the ever-dwindling laboratory teaching in these subjects. The use of these videotapes, developed using advanced computer graphics, data visualization and video technologies, will enrich the learning process of the current diverse engineering student body. This paper presents the details of this new method, the methodology used, the results and evaluation in relation to one of the structural engineering subjects, steel structures.     

Reliability based multiobjective optimization for design of structures subject to random vibrations

Based on a multiobjective approach whose objective function （OF） vector collects stochastic reliability performance and structural cost indices, a structural optimization criterion for mechanical systems subject to random vibrations is presented for supporting engineer＇s design. This criterion differs from the most commonly used conventional optimum design criterion for random vibrating structure, which is based on minimizing displacement or acceleration variance of main structure responses, without considering explicitly required performances against failure. The proposed criterion can properly take into account the design-reliability required performances, and it becomes a more efficient support for structural engineering decision making. The multiobjective optimum （MOO） design of a tuned mass damper （TMD） has been developed in a typical seismic design problem, to control structural vibration induced on a multi-storey building structure excited by nonstationary base acceleration random process A numerical example for a three-storey building is developed and a sensitivity analysis is carried out. The results are shown in a useful manner for TMD design decision support.     

Intelligent Job Aids For Professionals: Lessons Learned From Medicine

With the rapid advancements in artificial intelligence, computer science, and information management seen today, it is becoming increasingly feasible to improve the performance of professional white collar workers with intelligent job aids (i.e., expert systems). Already, performance technologists are advocating and predicting their wide spread adoption. Nevertheless, while such high tech performance interventions are relatively new to business, they have existed in medical research labs and clinics for nearly 20 years. Because of the almost ideal match between medical decision making and the emergent capabilities of knowledge engineering, artificial intelligence researchers made medicine one of their major testing grounds. In this article, I summarize the use of intelligent job aids in medicine as a source of insights for anticipating how they can and should be used by professionals in other areas. These insights include three generalizations which form the conclusion of the paper: (a) intelligent job aids must address a real need, (b) they must be compatible with professionals' larger “performance systems,” and (c) the adoption of intelligent job aids will depend as much on future trends as on the professionals' needs or performance systems.     

Modified particle swarm optimization for optimum design of spread footing and retaining wall

This paper deals with the economically optimized design and sensitivity of two of the most widely used systems in geotechnical engineering: spread footing and retaining wall. Several recent advanced optimization methods have been developed, but very few of these methods have been applied to geotechnical problems. The current research develops a modified particle swarm optimization (MPSO) approach to obtain the optimum design of spread footing and retaining wall. The algorithm handles the problem-specific constraints using a penalty function approach. The optimization procedure controls all geotechnical and structural design constraints while reducing the overall cost of the structures. To verify the effectiveness and robustness of the proposed algorithm, three case studies of spread footing and retaining wall are illustrated. Comparison of the results of the present method, standard PSO, and other selected methods employed in previous studies shows the reliability and accuracy of the algorithm. Moreover, the parametric performance is investigated in order to examine the effect of relevant variables on the optimum design of the footing and the retaining structure utilizing the proposed method.     

A Blast Shock Isolation System with MRFD and Its Semi-Active Control Analysis

To effectively reduce the damage to people and devices in civil defense engineering subjected to blast shock, a blast shock isolation system with magnetorheological fluid dampers (MRFD) is proposed. MRFD can provide continuously adjustable Coulomb friction and has many advantages for semi-active control. Numerical simulation of this isolation system is finished using Matlab simulink toolbox. General semi-active control algorithms are consided based on instantaneous optimal active control algorithm. And the results indicate that the shock isolation system can work efficiently, decreasing about 93% of the peak acceleration of the isolation floor.