Papers by Keyword: Structural Design

Abstract: It is possible to see various applications of mathematical optimization in civil engineering (structural design, reconstruction of transportation networks etc.) Initially, deterministic approaches have been introduced to solve these problems. But despite their complexity, these approaches are insufficient to comprehend the probabilistic nature of said problems and thus provide only suboptimal solutions. Hence the effort comes to reconsider these deterministic approaches and deal with uncertainties involved in said problems in less straightforward way. The goal of the paper is to present the algorithm for stochastic optimization of design of steel-reinforced concrete cross-section. This algorithm is based on internal cycle of deterministic optimization using reduced gradient method and external cycle of stochastic optimization using regression analysis. Firstly, the deterministic problem is introduced and described. It is followed by the description of uncertainties, which are involved in the process, and stochastic reformulation of the problem. Then the algorithm itself is introduced and the paper ends with presentation of the results of performed calculations.

Abstract: In the analysis of life cycle cost (LCC) according to the usage of all-composite structure, this study verified that economic operating cost impact occurring during operation is more important component than simple purchase cost in the review based on various economic components. Namely, all-composite structure requires the highest production costs based on LCC analysis, but entire LCC and ecological impact in the socio-economic aspect are important variables and all-composite structure is clearly the optimum alternative.

Abstract: Combined with shared service points in prime locations the use of Light Electric Vehicles (LEV) can help optimize the cost expensive „last mile“ of parcel service. [1] At the same time, a shared service point enables the switch from diesel driven engines to muscle-powered electric driving in cities. It is known, that in city operating courier services up to 80 % of actual used diesel fuel can be substituted by muscle supported electric driving. [2] To cover the needs of global operating parcel services a muscle-power supported LEV must meet the requirements of ergonomics (regarding usability in the modes drive and delivery) and parcel security. To gain economic benefits the construction of LEV for parcel delivery should be flexible enough to meet specific needs in cities - like the topography of the roadways, daily amount of goods to deliver and the legal provision at the local situation. Production of LEV in small and medium enterprises will unlock a niche for first industrial uses of Natural Fiber Composites (NFC) in load-bearing structures. By pre-impregnation a replicable quality will bring the structural light-weight construction with NFC to new fields of use, as the construction of a LEV will demonstrate. At the end of its life cycle, the vehicle proves further economic and ecological benefits due to the use of NFC: A cost effective thermal conversion under a reduced release of fossil CO₂ is guaranteed. [3; 4]

Abstract: Electronics devices consist of silicon chips, copper leads, resin or ceramics substrates and which are jointed to each other with solder, conductive adhesive or other materials. Each coefficient of thermal expansion is different and it causes strain concentration and cracks. The solder easily deformed by the difference of the thermal expansion and it relieved the stress on the devices however the epoxy resin of the conductive adhesives are harder. So we suggested the composed joint including the relaxation layers of low elastic material. The shear strength and elongation of the epoxy resin joint, silicone rubber joint and the composite joint of the two materials were investigated. The analytical study was carried out to clarify the stress reduction effect of the design of the relaxation layer in the composite joints. The parameters such as the width, height, pitch and the distance of the relaxation layer from the joint edge are investigated. The high relaxation layer close to the joint edge effectively reduced the stress of the joint. The stress reduction effect appeared in the different pitch of the layers.

Abstract: In order to reduce the weight of the car, which made molded plastic door through rotational molding process. According to characteristics of rotational molding process, design plastic doors structure using UG software. By contrast the design of traditional sheet metal door, introduces the rotational molding process several key technologies of structure design of door from the simple molding, doors internal strengthening of structures and accessories.

Abstract: The current paper deals with an overview on façade industry with the purpose to be useful for the engineers involved in the structural and architectural design of curtain walls.The research activity has been based on both the structural calculation and the experimental test on the Le Boulevard skylight in Doha (Qatar), measuring 36m by 18m in plan, located at a height of about 42 m and subjected to a wind load of 1.7 KPa. The skylight, composed of steel rectangular curved tubes, glass and aluminium sandwich panels, is designed for a basic wind speed of 25 m/s as per Qatar Construction Standards. Two types of steel frames have been designed, one to support both the glazing and aluminium sandwich panel, and another to transfer all the loads to the main structure. Subsequently, a performance testing on a specimen extracted from the skylight has been performed. The test was carried out by Aluminium Technology Auxilliary Ind. (ALUTEC) on a specimen having length and width of 6.625 m and 3.315 m, respectively. The assessment procedures have been carried out following the “ASTM E283”, “ASTM E331” and “ASTM E330” standards. The results of the test have been found within the acceptable limits for the skylight components specified by the standards and required by the project specification.

Abstract: A large number of tests has been carried out in the last 15 years all around the world to study the possibility to use recycled concrete aggregates (RCA) to produce structural concrete.Earlier tests indicated that RCA concrete had lower properties in comparison to ordinary concrete, such as lower elastic modulus, a more brittle post-elastic behavior, lower workability, higher shrinkage and creep.Most of these issues have been addressed to the content of cement mortar remaining in adhesion to the aggregate after the recycling processes and that cannot be totally eliminated without high economic and ecological costs. This cement mortar which has undergone the crushing process creates zones of weakness in the RCA, causes higher water absorption, higher concrete porosity and causes the decay of the aforementioned properties.More recent tests prove that Recycled Concrete shows this peculiar problems only with a percentage of substitution of standard aggregates with RCA higher than 30%. Under this percentage recycled aggregate concrete (RAC) can be considered as a standard concrete, on condition that an appropriate mix design is performed.

Abstract: The reason of lacking of a suitable front-end actuator when excavators moving massive objects, a new type of hydraulic engineering gripper was designed. Its design theory was showed. The use of SimulationXpress in the Solidworks to optimize the design, made the structure of cured rod more reasonable.

Abstract: Fibre reinforced concrete (FRC) has wide spectrum of advantages in tunnelling. Post-cracking behaviour of FRC wasn’t taken into account by Russian engineers while structural design led to underestimation of material abilities. New approach is based on fib Model Code 2010, which provides residual tensile strength Class of FRC. Research Center “FRC” (http://rcfrc.com/) carried out tests with specimens of different types of FRC, which supported by Russian Foundation for Basic Research. Research involved different specimens – plain concrete and FRC with macro-synthetic fibre of different dosage and types. The results showed the efficiency of each type of fibre. The Class of FRC was defined for each specimen series according to results.

Abstract: This paper deals with static analysis of load-bearing steel grid of a transparent roof. Ten structures with various spans (from 12.58 m to 30.08 m) and different heights (from 2.494 m to 7.471 m) have been modelled and analysed. The calculations were repeated for two common used types of the cross-sections - (60 x 40) mm and (60 x 60) mm. Permanent loads (the self-weight, the weight of glass panels) and variable loads (snow, wind) were taken into account. Obtained results were verified by four additional structures. The architects can use resultant graphs (the dimensions, maximum axial forces and maximum vertical displacements) in first stage of the design.