Advanced Materials Research Vols. 163-167

Abstract: According to anti-seismic design principle of strong column and weak beam, and of strong joint and weak member, reduced beam section(RBS) is often used to shift away plastic hinge from end of beam to weaken region of the beam. Reduced beam section with cut web are analyzed by non-linear finite element method(FEM) in this paper. Two kinds of effective suggested joints of reduced beam section(circled hole and long-circled hole) are put forward by comparing the results of mechanical behavior of reduced beam section with which of traditional RBS, including of ultimate load-carrying capacity, Von-mises stress distribution and the place of largest stress of beam end of the beam-column joints. A proposed seismic design method is put forward according to related chinese codes.

Abstract: Recently, a modified Particle Swarm Optimizer (MLPSO) has been succeeded in solving truss topological optimization problems and competitive results are obtained. Since this optimizer belongs to evolutionary algorithm and plagued by high computational cost as measured by execution time, in order to reduce its execution time for solving large complex optimization problem, a parallel version for this optimizer is studied in this paper. This paper first gives an overview of PSO algorithm as well as the modified PSO, and then a design and an implementation of parallel PSO is proposed. The performance of the proposed algorithm is tested by two examples and promising speed-up rate is obtained. Final part is conclusion and outlook.

Abstract: In order to acquire a high quality of living environment, it is necessary to investigate the subjects of floor impact sound insulation. According to the characteristics of optimization design method and restricted optimization math model, the sound transmission between floor and adjacent room down through floating floor has been modeled in a finite-element method. Floating floor structure are studied to realize the design optimization when the room average sound pressures are selected as objective function. Predicted results show that when keep the whole thickness of floating floor fixed, result of dynamics optimization design can reduce room average sound pressure effectively. And when keep the whole thickness of floating floor unfixed, optimization results have been gotten on the total thickness of floor layer and resilient interlayer of the floating floor, and the average sound-pressure in room is lower than original one availably.

Abstract: Using the conventional structural design methods, the design result is usually not the most economical and the most reasonable. While, using the single target structural optimization design method, duo to the only one target function to be optimized, the design result often can not meet with the multiple requirements of structural designing, furthermore its optimizing efficiency is low. So its application is limited. This paper proposes multi-target earthquake-resistant optimization design method for reinforced concrete frame structure under earthquake loading. In the optimization design approach, the ductility and cost which are two factors contradictory each other in structure designing are simultaneously taken as the target functions, and the function relation formula between them has been established, giving simultaneous consideration to the structural economy, safety and practicability. Using this design approach, the optimum cross-sectional dimensions, with the largest ductility and the lowest cost, of the reinforced concrete frame structure which is optimized under earthquake loading, can be obtained by computer. The practical examples of structure design, which have been optimized by using this approach, show that the cost of construction has been cut down by about 10% comparing with the conventional designing. The optimization process presented in this paper conforms entirely to the China national standards: “Code for Design of Reinforced Concrete Structures” (GB50010-2002) and “Code for Earthquake-resistant Design of Buildings” (GB50011). The theory and methods presented in this paper, having not only their theory meanings but their practical values, will be helpful for the structural design engineers and the researchers.

Abstract: Conventionally, when optimizing a structure, the single target structural optimization design method is usually used. However, this design result often can not meet with the multiple requirements of construction; furthermore its optimizing efficiency is low; so its application is limited. And more, as the objective function being generally continuous variable, the optimized result is not the structural module and this is inconvenient for construction. This paper, taking the structural strain energy and the cost of construction as the targets to be optimized, and the design variable being discrete, provides multiple-target earthquake-resistant optimization design method aiming at obtaining the largest stain energy and the lowest construction cost, and established the function relation formula between the strain energy and the cost of construction and obtained the satisfied result. The highlight of this process is adopting discrete variables as the design variables, therefore the optimized results (cross-sectional dimensions) will conform to the requirements of structural module and the engineering practice. The optimization process presented in this paper conforms entirely to the national standards: “Code for Design of Reinforced Concrete Structures” (GB50010-2002) and “Code for Earthquake-resistant Design of Buildings” (GB50011). The theory and methods presented in this paper will be helpful for the structural design engineers and the researchers.

Abstract: The minimum weight design method of large-span statically determinate trusses satisfying the displacement constraint is studied. The displacement calculation formula is provided, and the critical condition of minimum weight design satisfying the condition of allowed displacement is educed using Cauchy inequality. The distribution coefficient, which is used to obtain the minimum weight design, is defined and the coefficient distribution method is proposed. An engineering example is analyzed using the coefficient distribution method above, and the compared results are discussed. Study results show that the proposed method, coefficient distribution method, is correct，reliable and effective.

Abstract: By triangle finite elements, grillages with stress constraints are optimized. From it an optimal beams systems or plate with reinforced ribs is obtained. A truss-like continuum material is adapted. The material distribution field in design domain is optimized by fully-stressed criterion. The densities and orientations of the beams or reinforced ribs at nodes in grillages are taken as design variables. These densities and orientations vary in design domain continuously. The optimal distribution fields of moments, deformation and material are obtained simultaneously. Subsequently the discrete structures are determined based on the optimal distribution fields. A very simple geometry matrix of triangle plate element is given. The stiffness matrix of truss-like continuum in triangle element is derived. The optimization iteration procedure is suggested. The optimization procedure is accomplished by computer program automatically.

Abstract: Genetic algorithms (GA) have been shown to be very effective optimization tools for a number of engineering problems. Genetic algorithms which are based upon the principles of Darwinian evolution explores the region of the whole solution space and can obtain the golbal optimum. This paper introduces the standard GA and the forward-and-back search algorithms (FBSA) and demonstrates the use of improved genetic algorithms (IGA) for structure optimization of discrete variables. The mathematical model of structural optimization is derived. A 10-bar benchmark example is studied, the result shows that IGA, as an efficient method,can be applied to structure optimization of discrete variables.

Abstract: Ocean Data Buoy with fixed-point, real-time, long-term, continuous and accurate data collection capabilities is a modern ocean observing tools and instruments. Therefore, the reliability of information is essential, which depends on the stability of the working buoy. While the waves are acting, the buoys are difficult to maintain their stability. Based on Computational Fluid Dynamics, the force situations of buoy at wave conditions are simulated by using Variable Operating Frequency method and Fluent software. The variation of lift and drag forces and the changing trend of movement of buoy are obtained. And then the numerical value of force is adjusted by changing the height of waterline. At last, the digital design of shell structure is carried out with SolidWorks to improve the stability of buoys in surface wave.

Abstract: This article selects a typical compound block as the research object, which use construction waste and other solid waste as main raw material, and the finite element method is used to simulate. The temperature, thermal bridges and heat flux distribution of the block surface and interior, and drawn mainly thermal performance parameters are simulated and analyzed. Then the discussion on the block’s optimization and improvement was presented with the combined of simulation and experimental results, to improve its thermal performance and achieve better energy saving effect.