基于结构性能的建筑设计简史

从建筑师的角度来看,基于结构性能的建筑设计的发展过程,按时间顺序可以被划分为三个时代:在静力学图解时代中,由于图解静力学理论的建立和应用,建筑师能够清楚地表达结构概念并试图寻求结构性能的最优方案;在力学建构时代,由于社会经济需求和结构性能设计的发展,高结构性能的特殊结构原型被广泛应用,但由于方法的不可确定性和不可重复性,建筑师亟需新的设计计算工具辅助:在结构性能生形时代,建筑师充分应用电脑计算及模拟技术,为之前的实践方法和理论注入新的血液,更重要的是,建筑师创造了许多更为科学、准确以及创新的设计方法。文章以建筑视角对基于结构性能的建筑设计的发展历史进行梳理,比较和分析目前的结构基于性能的设计方法,并评估其对当下建筑实践的价值。

Numerical Analysis of Structural Progressive Collapse to Blast Loads

After the progressive collapse of Ronan Point apartment in UK in 1968, intensive research effort had been spent on developing guidelines for design of new or strengthening the existing structures to prevent progressive collapse. However, only very few building design codes provide some rather general guidance, no detailed design requirement is given. Progressive collapse of the Alfred P. Murrah Federal building in Oklahoma City and the World Trade Centre (WTC) sparked again tremendous research interest on progressive collapse of structures. Recently, US Department of Defence (DoD) and US General Service Administration (GSA) issued guidelines for structure progressive collapse analysis. These two guidelines are most commonly used, but their accuracy is not known. This paper presents numerical analysis of progressive collapse of an example frame structure to blast loads. The DoD and GSA procedures are also used to analyse the same example structure. Numerical results are compared and discussed. The accuracy and the applicability of the two design guidelines are evaluated.

Static load test and load transfer mechanism study of squeezed branch and plate pile in collapsible loess foundation

As a special geological phenomenon, the character of collapsible loess foundation is collapsible when penetrated by water. This character leads to the soil losing load bearing capacity largely and may lead to foundation failure. Pile is a popular foundation used in collapsible loess. The squeezed branch and plate pile is a new type of pile developed in recent years and has not be used in a project before. In this paper three squeezed branch and plate piles are tested in collapsible loess after immersion processing. The results may be used for reference in similar construction project, and to provide theoretical references for de- signing of the squeezed branch and plate piles in engineering practice.

Vertical bearing capacity of pile based on load transfer model

The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.

Nature and Kinetic Architecture： The Development of a New Type of Transformable Structure for Temporary Applications

The contemplation of contemporary architectural designs shows an increasing demand for the development of more adaptable, flexible and transformable structures. This type of structures can adapt with different environmental conditions and meet different functions. This can help in reducing environmental waste and pollution associated with many buildings and above all can save on cost and time. Natural systems have inspired human being, since they began to build and design. Architects and designers have utilized nature as one of the main resources of information for the creation of innovative architectural spaces. One of the unique features of natural structures is the way that their components open and close in order to respond to a particular requirement or the environmental changes. This aspect has inspired many designers for the development of transformable architectural structures that can change their shape and geometry to be able to adapt with specific conditions. To make a way toward the design of transformable structure for temporary applications, the authors have developed a new type of adaptable structures according to natural forms. The proposed design applies the transformation principles that exist in potato＇s flower and the movement mechanisms used in a spider＇s leg. The design is able to fit to different topographies and have a potential to be folded to a very compact state in a very short period of time. The detailed design and the different configurations of the system applications will be presented in this paper. The result of the study shows that using modular triangular plates can create a changeable module that is not only able to respond to different functions and environmental changes but it is also able to shape different configuration to be able to respond to different user＇s ambitions. The compactability of this structure into 1/3 of its base dimensions; makes its transportation fast and with minimum costs. These capabilities make this structure suitable for temporary buildings such as exhibitions, temporary settlements or hospital in damaged areas.

Dynamics Simulation Model of the Economic System in Mining Area

The system dynamics is a new subject that was put forward by Professor J W. Fortester in dmerican MIT in 1950s. It is extensively applied to systematic problems af high phase, nonlinear, multtdimensionality, multiple feedback and complicated time-variation. In this paper, the complex system in mining area is divided into five parts - resources, environment. economy, population, and science and technology. The.five parts are regarded as five sub-models. By taking the economic subsystem as an example, the SD model of complex system in mining area is established. This model has certain universality and practicability.

A Method to Improve First Order Approximation of Smoothed Particle Hydrodynamics

Smoothed particle hydrodynamics (SPH) is a useful meshless method.The first and second orders are the most popular derivatives of the field function in the mechanical governing equations.New methods were proposed to improve accuracy of SPH approximation by the lemma proved.The lemma describes the relationship of functions and their SPH approximation.Finally,the error comparison of SPH method with or without our improvement was carried out.

Static and Dynamic Analyses of Long-Span Spatial Steel-Cable-Membrane Hybrid Structures

With the increment of the complexity of structural systems and the span of spatial structures, the interactions between parts of the structures, especially between some flexible substructures, become too complex to be analyzed clearly. In this paper, taking an actual gymnasium of a long-span spatial steel-cable-membrane hybrid structure as the calculation model, the static and dynamic analyses of the hybrid structures are performed by employing the global analysis of the whole hybrid structure and the substructural analysis of the truss arch substructure, the cable-membrane substructure, etc. In addition, the comparison of stresses and displacements of structural members in the global and substructural analyses is made. The numerical results show that serious errors exist in the substructural analysis of the hybrid structure, and the global analysis is necessary for the hybrid structure under the excitation of static loads and seismic loads.

The Effectiveness of Using Constructive Learning Strategies in Teaching English Language on Developing the Achievement of Grammar, Translation, and Critical Thinking Skills for the Third Grade Intermediate Students

The study aimed to reveal the effectiveness of the integration between some constructive learning strategies in teaching a unit of the English language course to collect translation skills, using grammar, and the acquisition of critical thinking skills for intermediate third grade students in Mecca. Also, it aimed to acknowledge the statistical differences between the modified averages for the study sample groups degrees in the dimensional collecting of grammar and translation skills at the knowledge of the grammar level and using it, and at the macro level for collecting translation and grammar skills after adjusting the old collecting, as well as the knowledge of the statistical differences between the modified averages for the study sample groups in the total telemetric for the critical thinking skills after adjusting the old collecting. To achieve the study objectives, the researcher used the semi-experimental method that had several experimental groups （four groups）, and applied it to a sample of intermediate third-grade students in the city of Makkah （99 students） in teaching the unit of the English language course, which is （Healthy Eating） in the second semester in 2011/2012. After using the appropriate statistical methods, the study came to a result that there are no statistically significant differences in the old implementation for the test of skills of academic achievement of grammar, translation, and critical thinking skills, and that there are statistically significant differences in the new implementation due to the four strategies. According to the results of the study, the researcher recommended a number of recommendations including： the necessity to focus on the constructive theory in teaching English language skills, the importance of expanding the use of the suggested integrative oriented and its development in the field of English language teaching, to hold an intensive training courses for teachers of the English language to train them on using the suggested integrative strategy, the emphasis on the importance of the curriculum activities which focus on the integration between the constructive learning strategies, the importance of expanding of scientific research in the field of integrative strategies, and the development of synthesis methods that combine two strategies or more.

Interactive English Reading Community Based on Social Network Sites

One of the major trends in the reform of English language teaching is the application of network technologies. This paper discusses the application of social network sites in building an interactive English reading community under the guidance of the constructivist learning theory and its influence on the learners＇ English reading. This SNS-aided reading community puts the students as the center and the teacher the guide, embodying students＇ subjectivity, equality, and interactivity. The study shows that the interactive English reading community can motivate students to read, improve their reading skills, and thus develop a new SNS-aided English reading model for English learners.

Model Order Reduction of Complex Airframes Using Component Mode Synthesis for Dynamic Aeroelasticity Load Analysis

Airframe structural optimization at different design stages results in new mass and stiffness distributions which modify the critical design loads envelop. Determination of aircraft critical loads is an extensive analysis procedure which involves simulating the aircraft at thousands of load cases as defmed in the certification requirements. It is computationally prohibitive to use a GFEM （Global Finite Element Model） for the load analysis, hence reduced order structural models are required which closely represent the dynamic characteristics of the GFEM. This paper presents the implementation of CMS （Component Mode Synthesis） method for the generation of high fidelity ROM （Reduced Order Model） of complex airframes. Here, sub-structuring technique is used to divide the complex higher order airframe dynamical system into a set of subsystems. Each subsystem is reduced to fewer degrees of freedom using matrix projection onto a carefully chosen reduced order basis subspace. The reduced structural matrices are assembled for all the subsystems through interface coupling and the dynamic response of the total system is solved. The CMS method is employed to develop the ROM of a Bombardier Aerospace business jet which is coupled with aerodynamic model for dynamic aeroelasticity loads analysis under gust turbulence. Another set of dynamic aeroelastic loads is also generated employing a stick model of same aircraft. Stick model is the reduced order modelling methodology commonly used in the aerospace industry based on stiffness generation by unitary loading application. The extracted aeroelastic loads from both models are compared against those generated employing the GFEM. Critical loads modal participation factors and modal characteristics of the different ROMs are investigated and compared against those of the GFEM. Results obtained show that the ROM generated using Craig Bampton CMS reduction process has a superior dynamic characteristics compared to the stick model.

Guidance of Constructivist Theory for English Teaching

The traditional English teaching methods are mainly based on teachers＇ words and students＇ listening type. Neither the quality of teaching can be guaranteed, nor are students＇ thinking ability and innovation developed. To change this situation, many educators have done a lot of research and exploration from both theoretical and practical aspects, of which constructivist theory is one of main results. Constructivist theory emphasizes that leaming is a process of knowledge acquisition. Knowledge can not only get from teachers, but also requires learners to learn from others＇ help in some particular context, with the necessary leaming materials, and through a way of meaning construction. Besides, it has important reference and inspiration effects on discipline study and conducting educational research.

Geodynamic modeling of thermal structure of subduction zones

During subduction processes, slabs continuously have heat exchange with the ambient mantle, including both conduction and advection effects. The evolution of slab thermal structure is one of the dominant factors in controlling physical and chemical property changes in subduction zones. It also affects our understanding of many key geological processes, such as mineral dehydration, rock partial melting, arc volcanism, and seismic activities in subduction zones. There are mainly two ways for studying thermal structure of subduction zones with geodynamic models: analytical model and numerical model. Analytical model provides insights into the most dominant controlling physical parameters on the thermal structure, such as slab age, velocity and dip angle, shear stress and thermal conductivity, etc. Numerical model can further deal with more complicated environments, such as viscosity change in the mantle wedge, coupling process between slabs and the ambient mantle, and incorporation of petrology and mineralogy. When applying geodynamic modeling results to specific subduction zones on the Earth, there are many factors which may complicate the process, therefore it is difficult to precisely constrain the thermal structure of subduction zones. With the development of new quantitative methods in geophysics and geochemistry, we may obtain more observational constraints for thermal structure of subduction zones, thus providing more reasonable explanations for geological processes related to subduction zones.

Modeling and analysis of a predator-prey model with state-dependent delay

We propose and study a predator prey model with state-dependent delay where the prey population is assumed to have an age structure. The state-dependent delay appears due to the mature condition that the prey must spend an amount of time in the immature stage sufficient to accumulate a threshold amount of food. We perform a qualitative analysis of the solutions, which includes studying positivity and boundedness, existence and local stability of equilibria. For the global dynamics of the system, we discuss an attracting region which is determined by solutions, and the region collapses to the interior equilibrium in the constant delay case.

Patient-specific modeling of left ventricle mechanics

We present a computational framework for the study of cardiac motion.The bio-mechanical model captures the passive and active properties of the cardiac tissue as well as the fiber architecture.We focus on the analysis of deformations of a beating left ventricle(LV),comparing numerical simulations with real data acquired by echocardiography.The goal is to determine the clinical relevance of the LV strains pattern and to investigate the relationships between that pattern and the arrangement of myocardial fibers.The proposed framework could in principle be used for a wide range of clinical applications.

Non-linear Aerothermoelastic Modeling and Behavior of a Double-wedge Lifting Surface

The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic instabilities.The thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes.The dynamic behavior of a double-wedge lifting surface with combined freeplay and cubic stiffening structural nonlinearities in both plunging and pitching degrees-of-freedom(DOF) operating in supersonic/hypersonic flight speed regimes has been analyzed.In addition a third order piston theory aerodynamics(PTA) is used to evaluate the non-linear unsteady aerodynamic loads applied to the wing section.Loss of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also considered.The aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed airstreams.It is demonstrated that serious losses of torsional stiffness may occur in such lifting surfaces;the influence of various parameters such as flight condition,thickness ratio,freeplays and pitching stiffness nonlinearity are discussed.

Modeling of microbial growth bioprocesses： Equilibria and stability analysis

The paper addresses the analysis of nonlinear dynamical models of some microbial growth processes. Equilibrium points, stability analysis, and structural properties are studied for different bioprocesses with various kinetics structures. First, a simple micro- organism growth process on a single limiting substrate is widely analyzed. Second, a microbial growth process combined with an enzyme-catalyzed reaction is investigated. The analysis shows that these kinds of bioprocesses have multiple equilibria, stable or unstable, operational or non-operational. The partition of nonlinear model in linear and nonlinear parts via some structural properties leads to kinetic decoupling and facilitates the equilibria and stability analysis. The performed research is useful for model reduction and for the design of observers and control algorithms. To illustrate the study results, several numerical simulations are provided.