Abstract: The problem of static analysis of a circular cylindrical shell, which is located on elastic Winkler foundation and reinforced by the longitudinal edges are considered. There is rib stiffness of rectangular cross section. Exposure is represented evenly distributed along the longitudinal axis forces. The forces acting on the edges of the rigidity of the upper structure. Agreed that the ends of the envelope is flat, vertical walls, giving the contour of the absolute rigidity in the transverse direction and does not prevent the longitudinal displacement of points of the envelope. To solve the problem, the total moment theory of circular cylindrical shell was used. To implement the proposed algorithm is the calculation of computer program. With the help of the program is executed a number of examples of calculation. In these examples, analyze the impact of stress on the shell of such factors as the relative length and thickness, angle mortar shell, the value of the relative rigidity of airborne elements and other.
Abstract: The separation reliability and shock response of a state-of-the-art non-fracture Super-Zip separation device have been analyzed. The simulated results showed that the minimum peak value of the internal pressure for separating of the non-fracture Super-Zip separation device was quarter of the conventional Super-Zip separation device. At the same time, on account of the non-fracture separation mode, the structure near the state-of-the-art non-fracture Super-Zip separation device had lower impact acceleration responses comparing with the conventional Super-Zip separation device.
Abstract: Paper presents current technologies and building structure used in wood-framed multistory buildings and also refers to calculation methods of strains and stresses. Structure of these buildings is recently based on modular technology. Elements in the form of module are constructed in the industrial plant and then delivered to the site for assembling. The wood-framed building structure undergoes significant deformations relevant to changes of moisture content in material and resulted from load acting perpendicular to the grain direction in wood. In four story building the vertical displacement of the top floor has been estimated to over 80 mm. FEM model with application of the shell elements in description of posts, beams and sheathing and applying the beam finite elements in description of linking fasteners is used in stress evaluation in structure. The model permits for precise analysis of stresses in overloaded parts of structure distinguishing to the other simplified analytical models of analyses. Analytical model leads to determination of stresses under typical exploitation standard loadings and in result of non-typical loadings arising at the time of module handling within assembling.
Abstract: UHTCC (Ultra High Toughness Cementitious Composite) is a new type of material which is widely used in this study. It is a kind of cement-based material with very good toughness. It is effective to improve the performance of damaged reinforced concrete and improve its durability. UHTCC is widely used in the reinforcement of concrete structures. There is no clear and effective method for calculating it. There is an approximate formula for the crack width of ordinary concrete. The concept of an average crack spacing is used in the derivation of the formula. The limit of UHTCC for cracks can be measured by the concept of average crack spacing. According to the obtained crack width limit, the reinforcement effect of UHTCC can be shown.
Abstract: The corrosion of concrete structures is serious in sulfuric acid environments. Corrosion damage of reinforcements caused sulfuric acid corrosion is very serious. The rapid experiments of sulfuric acid corrosion steel bars were carried out, and the apparent morphology and mechanical properties of sulfuric acid corrosion steel bars were studied. The results show that the corrosion of steel bars is uniform corrosion. With the increase of corrosion rate, the yield platforms and the yield strengths and ultimate strengths are reduced. Based on the experimental datas, the relationship models between yield strengths and ultimate strengths and corrosion rates were obtained. The constitutive models of corrosion steel bars were established. The stress - strain relationship model is in good agreement with the experimental data.
Abstract: This study used a sodium hydroxide (NaOH) solution to activate a mixture of water treatment sludge, fly ash, and slag, in order to produce a new alkali-activated controlled low-strength material (CLSM). Fresh properties of this new CLSM were investigated through the tests of workability, setting time, and ball drop time. Test results show that the addition of water treatment sludge (WTS) decreased workability. In addition, the addition of such WTS increased initial setting time and ball drop time, whereas the alkali equivalent (AE) shortened the initial setting time and ball drop time. At a liquid-to-solid ratio (L/S) of 0.9, a WTS content of 10%, and an alkali equivalent of 9%, the fresh properties for the CLSM conforms to the design principles and provisions of the Public Works Department, Taipei City Government, and is ideal for road construction in order to reduce traffic impact.
Abstract: The attenuation of stress wave induced by impact load in multi-layered thin cylindrical rods has been investigated and analyzed. Firstly, based on stress wave propagation theory, the one dimension solution of the response of stress wave in three-layered media has been given. Secondly, a three-layered thin cylindrical rod has been established through FEM, and the propagation and attenuation of stress wave in it has been analyzed. The analytical and numerical results showed that the stress wave attenuation could be achieved by using multi-layered media.
Abstract: A study has been conducted to investigate the potential use of mengkuang leaves or Pandanus atrocarpus bonded with epoxy resin as external strengthening material for the strengthening of reinforced concrete (RC) beams. Physical and mechanical properties as well as structural properties of the mengkuang leaves-epoxy composite plates (MLECP) were evaluated in this study. Chemical treatment was performed on the dried mengkuang leaves using sodium hydroxide (NaOH) with concentrations of 2%, 5% and 8%. Scanning electron microscope (SEM) and flexural strength tests were conducted on the mengkuang leaves and flexural specimens, respectively. All the beams were tested to failure under four-point loading. Results showed that the flexural strength of the composite with 0.3 fiber volume ratio exhibited the highest flexural strength. Strengthening of RC beam using MLECP managed to increase the beam capacity.
Abstract: Northeast Extreme Tee (NEXT) beams have been recently developed for the accelerated bridge construction. The skew effect on live load distribution in a NEXT beam bridge, especially with integral abutments, is not clear and shall be assessed. In this paper, various skew NEXT beam bridges are evaluated through validated finite element (FE) analyses with solid brick elements. Parameters as studied include beam section, span length, and skew angle. Per AASHTO LRFD specifications, one- and two-lane loaded cases are examined to obtain the maximum tensile strains in beam stems under the design live loading (HL-93). Unskewed bridges are used as control specimens to compute skew reduction factors (SRF) for moment from the obtained FE strains. The FE- and LRFD-SRFs for moment are compared in terms of figures, which indicate the LRFD-SRFs have good agreements with the FE-SRFs at large. For the majority of the bridges, LRFD-SFRs govern the FE-SRFs. The research findings from this paper are useful for practicing engineers to safely design a skew NEXT beam bridge with integral abutments.