Calculation of environmental cost in the structural optimization of super tall buildings

Chinese mainland has seen a rapid construction speed of super tall buildings in recent years. Due to its huge quantity material and energy assumption, the super tall buildings exert great impact on the environment. An innovative new life cycle model is proposed for assess and optimize the life cycle environmental cost of super tall buildings. The new life cycle model has two features. Firstly the space distribution of the building materials is considered besides the time dimension, and secondly the single life cycle concept is extended to multiple life cycles to investigate the carbon footprint from the perspective of more than one life cycle. A benchmark super tall building is established to illustrate the application of the proposed new life cycle model. According to the case study results, a remarkable difference would be made in carbon emissions if the life cycle environmental cost based structural optimization method could be applied.     

Eco-sustainability Assessment of Building Projects Based on Eco-footprint

The life-cycle eco-footprint computing model of building projects was established in the study. It contained the eco-footprint in 4 aspects during the lifecycle: consumed energy, consumed resource, emitted carbon dioxide and produced solid waste. Space efficiency of life-cycle eco-footprint index was proposed and used to assess the eco-sustainability of building projects. Then, the eco-footprint and ecosustainability of 4 different structure types(brick-concrete bungalow, multi-storey brick-concrete, multistorey steel-concrete, high-rise steel-concrete) for residential building in severely cold areas were investigated. The results indicated that: 1) Compared with bungalow, high-rise building with relatively smaller shape coefficient and window-wall ratio had higher eco-sustainability; 2) For the buildings with the same storey, shape coefficient and window-wall ratio, steel-concrete building had higher eco-sustainability than brickconcrete building; 3) High-rise steel-concrete structure had the greatest eco-sustainability during the 4 different bui lding structures, so it was more suitable to promote.     

Service Life Prediction of Concrete Structures under Chloride Environment

The problems rendered from the conventional time marching, referring to stepwise time marching scheme (STMS) adopted in boundary element method (BEM) for chloride diffusion in concrete structures, were investigated, and a new time marching, referring to initial time marching scheme (ITMS) in BEM, was developed for evaluation of service life of the concrete structures under chloride environment. Results of the numerical examples show that the ITMS-BEM proposed can eliminate domain integral and simplify the computational model, so that the stability in iteration process can be improved, resulting in better efficiency and accuracy, compared with the STMS-BEM. It can also be concluded that the dimensions of the diffusion of chloride can affect the service life of the concrete structure significantly, which should be taken into account in structural design.     

Practical Method of Form-finding of Semi-rigid Structures

Based on the discussion of the simulation for the cable prestress, the rigidity theory was used to identify the geometrical dimensions of semi-rigid structures in zero state. When the structural geometry in initial state is given, the geometrical dimension in zero state is determined by the initial prestress distribution. The contribution-matrix method is firstly applied to get the initial lack of fit. However, the influencing factor of initial lack of fit on the displacement of control point is linear superposition, that is, the structural response is linear, and it is irreconcilable with the geometry nonlinear of semi-rigid structure. In order to reduce the error of nonlinear structural response, the influencing factor in the contribution-matrix method is revised, and modified contribution-matrix method is put forward. Programs by ANSYS parameter design language APDL are worked out for the form-finding analysis of beam-string structure of a practical project. The numerical results show that the modified contribution-matrix method reduces the errors of the assumption of structural linear response. And it can be applied to the form-finding of semi-rigid structures with small stiffness.     

A Preliminary Survey on Analysis Method of Building Structures Under Post-Earthquake Fire

Considering the impact of post-earthquake fire on building structures in structure design, an analysis method is proposed to analyze and simulate the response of building structures under post-earthquake fire. Based on the seismic response and thermal stress analysis, this method considers the structure seismic damage through a simplified seismic damage model, and the simulation of the response of building structures under post-earthquake fire was reached by linking the heat transfer analysis and thermal stress analysis to the results of seismic damage. A single-storey concrete frame and a multi-story concrete frame were analyzed with this method and compared with experimental results of the same concrete frame under fire without seismic damage. It is shown that the collapse mode may change for seismic damaged structures and the fire resistance decreases with the increasing of seismic damage degree.     

Development Trend of Computer Aided Architectural Design(CAAD)

Through the review of history of CAD and CAAD technology development,combined with the application condition of CAAD technology in architectural design,this paper analyzes the theory and advantage of Virtual Building design,dissertates the development trend of computer aided architectural design(CAAD).The Virtual Building model is a complete database including all of the building information,which can be applied in the whole building industry such as building design,structural design,facility management,costing etc.,so as to manage all of the information during the building's life circle.     

Innovation of Construction Projects Management Based on the Five-dimension Modeling

Nowadays,the computer technology is applied more and more widely in the architecture,engineering and construction industries(AEC).This paper introduces a methodology of construction project management based on the five-dimension modeling which integrates three-dimension building models,resources and schedules by the development of virtual construction technology.The application of this method also influences several aspects of project management such as range,time,cost,resource,communication and information management.Finally,the process of 5D modeling and the management practice are presented through a real life case in Beijing which proves to be a more efficient,productive and economy project.     

The Non-Linear Finite Element Analysis of Cable Structures Based on Four-Node Isoparametric Curved Element

In this paper,based on the geometric nonlinear behavior of cable structures,a finite element method with four-node isoparametric element was presented,the third order polynomial was used as displacement functions and initial curve of the element.By means of the principle of virtual work and the updated Lagrangian method,the authors derived the finite element equations,and solved them by Newton-Raphson method.The proposed model leads to high precision and can meet the engineering requirements.The model presented in this paper can be applied in the analysis of long-span tension structures,such as cable structures,cable domes and so forth.     

乳制品冷链物流的库存-生产策略优化研究

在日益激烈的企业生存竞争中,针对乳制品生产企业如何选取合适的生产批量和库存水平的问题,提出了成本-时间-客户满意度的三目标优化模型。首先,考虑乳制品的库存费用、周转时间和客户满意度,分别建立库存生产成本、库存周转时间和客户满意度优化模型;其次,以生产批量和库存水平为决策变量,应用多目标遗传算法,集成库存生产成本模型、库存周转时间模型和客户满意度模型,求出所有非劣解;最后,应用伪权向量法,通过保质期不同的产品验证提出的模型。结果表明,对于不同保质期的产品,均可得出最优库存生产批量大小和最优库存水平。     

Numerical Simulation Analysis on Ductility Performance of High Strength RC Frame Structure

High-strength concrete has been widely used in civil structures for advantages of higher-strength, earlier curing strength and smaller deformation in applications. However, relatively weak ductility in structures in seismic zones prevented it from further application. The ductility of the structure can be improved by reinforcing reasonably rebars in correct details. A high strength RC frame model with twelve floors and two bays is numerically analyzed by using DRAIN-2DX program. It was shown that this worked fairly well in simulation of the process of structural damage and energy dissipation capacity. It also showed that this kind of frame structure has good ductility and dissipation capacity as well as great seismic performance. The proposed method can be applied in high-strength concrete structures in seismic zone.     

AN EFFECTIVE DESIGN METHOD FOR PREVENTING COL LAPSE OF MULTI-STORY BUILDINGS TAKING ACCOUNT OF STRUCTURAL LOW-CYCLE FATIGUE CHARACTER

In this paper, through the theoretical analysis and a number of calclating, the statistic regression about the parameters in the failure criteria for aseismic structures presented by the authors are made. Based on this work, a simplified method for preventing collapse of multistory buildings taking account of structural low-cycle fatigue character is proposed.     

MODIFYING STRUCTURAL DYNAMIC MODEL USING AN INCOMPLETE SET OF MEASURED COMPLEX MODES

A method is presented in this paper which uses an incomplete set of complex modal parameters identified from the experimental date to modify the structural dynamic model. The method, not requiring iteration and being programed easily,is suitable for the complex structures with general viscous damping in improving the analytical mass, damping and stiffness matrix madel of a structure with a set of minimum changes in the analytical matrics, so as to force the eigensolutions to agree with the test measurement. An example is given to demonstrate the validity of this proposed method.     

Fatigue Maintenance Probabilistic Optimization of Cable-girder Welded Anchorage Zones in Suspension Bridges

it is necessary to balance the failure risk and the maintenance expensive. A methodology for reliability based maintenance optimization of steel bridge welded joints subjected to fatigue is proposed considering linear elastic fracture mechanics (LEFM), the structure reliability, life cycle cost method and maintenance strategies. The maintenance cost is divided into inspection, repair and failure sections according to the whole life cycle cost methodology. And the maintenance strategy is transformed to the minimum expected lifetime costs with a constraint of the minimum acceptable reliability index. An case concerning to a transverse stiffener of bottom flange welded joint of Qingcaobei bridge is studied with a certain number of simplifications. Some sensitivity analysis is provided. Among all the parameters, discount rate is the most remarkable.     

Cost forecast model for power engineering based on based on back propagation neural networks

A novel power engineering cost forecast model was proposed by combining feature extraction and small sample learning. The initial data was preprocessed with principal component analysis to remove the correlation among the original indexes and get the potential independent indexes. The new indexes acted as the input set to build a new forecast model based on least squares support vector machines. The results of this model were compared with the forecast results getting from artificial neural network. By comparing the forecast results with different principal components number, the optimal number was determined to achieve the desired forecast effect. The prediction results indicate that the method can extract the feature of initial data effectively and is good at small sample learning . The expected forecasting results can be reached.     

Quantitative Parametric Analysis of Soft Clay Structure

It is a fundamental task for soil structure study to find a quantitative parameter that reflects structural damage under pressure. Based on the unidirectional compression and isotonic compression tests of soft clays from Huangshi, Zhangzhou and Qingdao, the compression properties of structure soil and the effect of different conditions on the properties were investigated. It is found that when the pressure is lower than structure yield stress, it is mainly the initial structure self alignment procedure and the structure is in few damage and the compressibility is small. When the pressure is bigger than the structure yield pressure, the structure destroys massively and the compressibility increases greatly not only from inter granular slipping but also from the collapse. With the damage properties in compression, a new coefficient was proposed to evaluate the structural behavior. And this parameter can be obtained simply through the software AutoCAD. With the proposed method, it is found that the soft clay in Qingdao is strongest in structural behavior, followed with that in Huangshi and Zhangzhou.     

Ascertainment of the Cost of Construction Product in Construction Tendering and Bidding

The Tendering and Bidding Law" states that the bidder should not compete bidding through quoted price lower the cost, but it does not ascertain the meaning of the cost of building product. It is the purpose of this paper to ascertain the meaning of the building product cost. The calculation bases of both the social average product cost and of the enterprise individual product cost are analyzed and they are compared with each other. The authors point out that for some enterprise there is individual product cost lower the social average product cost. The function of design mechanism of bidding is revealing "private information" on "the lowest price". The purpose of carrying out bidding is introducing competition, reducing the cost for the owner and realizing the maximum yield. Both indicate the cost of building product, mentioned in "The Tendering and Bidding Law" should be the enterprise individual product cost.     

Product ontology screening and its application in variant design

A product ontology screening method which can be used in variant design is proposed. With the support of complete ontology view of product resources, the product functional requirement and structural characteristics are converted to demand constraints, which are used to screen product ontology. For different screening hierarchies and objects, different screening rules such as pattern matching, case matching combined with manual decision and auto matching on the basis of case-based reasoning are adopted. The semi-automatic screening method with human-computer cooperation has impressive effectiveness on the improvements of the accuracy of design schemes and the flexibility and efficiency of design process. Finally, a variant design supporting system for building door and window is developed, which proves the feasibility and effectiveness of the method.     

Application of Fractals in Architectural Shape Design

A computer aided method for architectural shape design was developed based on the L systems algorithm, the shape grammar and the space surface equation theory. Various 3D entities such as building grounds, building walls and building domes with fractal characteristics could be generated in a short time by using the computer program. These generative 3D entities were saved in a component database which could help to accumulate design knowledge through continuous expansion. A building could successfully be formed by the designers through selecting proper building grounds, walls and domes from this database. The effectiveness of the proposed method was approved with a case study.     

Effect of Reinforced-Concrete Deterioration on Structures

s:It is proposed that the research of the structural durability is necessary considering the structural damages under the effect of deterioration of reinforced concrete. The most common reasons, which cause the deterioration of structures in China, are reinforcement corrosion and freeze thaw cycles of concrete. Based on the summarizing of research works of the effect of reinforced concrete deterioration on structures, it is indicated that the structural durability research should be carried out either in view of material science or that of structural science, and should be also considered the interaction of several factors with uncertain nature instead of the determined individual factor analysis. The structural durability of serviceable should be paid much more attention while researching the durability of structural capacity. The effect of reinforced concrete deterioration on structural capacity, rigidity and durability should be researched henceforth.     

A Discussion on How to Control Project Cost during Construction Stage

In this paper, how to effectively control building cost under the current situation is discussed, due to that the engineers take part into project management only in the stage of construction. It points out that the engineers should notice the following issues when applying cost control: they should be experienced with necessary knowledge on building cost and contracts control, analyze each cost in bills of project volume carefully, sign a set of reasonable contracts, pay attention to the site sign, understand their skills of claim for compensation and pay much attention to cost control during settlement stage.