Applied Mechanics and Materials Vols. 105-107

Abstract: The experimental results of crack torque and ultimate torque of six reinforced concrete special-shaped columns under the combined actions of pressure and torque were presented firstly. Then, the calculation formula suggested by the Chinese Code for Design of Concrete Structures for the crack torque and ultimate torque of rectangular columns under the actions of pressure and torque were used for reference to determine the expression forms of crack torque and ultimate torque of special-shaped columns. Moreover, the special-shaped cross section was dealt as a combination of two rectangle cross section. A practical calculation method for crack torque and ultimate torque was proposed by data regression of experimental results.

Abstract: From the angle of saving material, the author make the related computing, as well as compare and analysis to the biggest torsion shearing stress of the hollow or solid circle cross section shaft. Simultaneously it is elaborated, when the most torsion shearing stress of the hollow circular cross-section axis is smaller than the solid circular cross-section axis, the rule of economizing material and the change of the appearance size. Elaborate further, the related reasonable sizes are given, in order to have the prior adoptions during the design or transform. For example, the ratio of the hollow circle cross section shaft external diameter and inner diameter is two in the engineering, and the economical material is in 15%-inside 25% ranges.

Abstract: Since China's enforcement of building energy saving standards, external insulation technology has been applied in a mount of buildings. However, four common defects of it, namely crack, shedding and hollow, leakage, frost and condensation, had gradually appeared. This study tries to find out the critical construction techniques of preventing these defects which are closely related to quality in order that engineers pay more attention to them during construction. Literature research and field investigation to engineers and technicians are adopted. Designed questionnaires, including 61 kinds of detailed defects causes and relevant preventive measures, are used in the survey. Through statistical analysis of survey data, the mesh, plastering mortar configuration, etc. 10 detailed causes are suggested as main defect reasons according to harm grade. Meanwhile, corresponding 15 highly effective construction technical countermeasures are put forward finally.

Abstract: Abstract. The construction enterprise is one of the important management ways, and it also is main mean of controlling the project schedule, quality and cost. Although outsourcing can be good for integration of resources to realize the optimization of resources, due to the contracting enterprise and the unbalance of interest conflict between them and other factors, the risk is certain to bring. The correct evaluation to the risk is an important basis for decision-making. This paper is used by using information diffusion method to the construction risk analysis on the exploration, and analyzing the error, to proof that the information diffusion method in building construction risk analysis is of the application of the feasibility, which can make full use of the existing information. By adjusting the domain of discrete points the density of the degree so that the request reaches the required accuracy.

Abstract: According to one three-story RC frame structure, the results of time-history analysis of using re-centring SMA damper to seismic retrofitting are introduced in detail. Damping effect of dampers is studied by index such as floor displacement, story drift, story shear force, energy dissipation, etc., and optimal layout of dampers is also discussed. The analysis results indicate that floor displacement and story drift are decreased greatly after strengthening, and story shear force is controlled to some extent with good effect. The damper dissipates most of the total energy inputting into structure and also has good ability to re-centring. The damper can obtain good energy dissipation when arranged at the maximum story drift, and less energy dissipation when arranged at the smaller story drift.

Abstract: It is a key point of durability deterioration to reinforced concrete structures that protective layer concrete cracking, so it is essential to assess the durability limit state to determine the critical corrosive ratio. In this paper the Franc2D tool has been used to simulate the corrosive expanding process of protective layer concrete in reinforced concrete structure, and the slope change of the ρ-CMOD curve has been used as the basis to determine the critical corrosive ratio, then the effects of stirrups to critical corrosive ratio and the corrosive expanding crack width has been studied. It has been showed a linear relationship between the corrosive ratio and crack width, and appearance of corrosive expanding cracks has been delay with the stirrups, on the other hand crack propagation speed can be reduced with the stirrups across cracks effectively.

Abstract: Based on earlier theoretical works on RC beams ,the mechanical properties of steel reinforced concrete beams strengthened with NSM (near-surface mounted) CFRP (Carbon fiber reinforce polymer) rods are further investigated theoretically including theirs failure mechanism and load ability. According to the stress patterns of steel reinforced concrete beams strengthened with NSM CFRP rods and different position between neutral axis and steel, the discriminant formula of the boundary destroys and the formula of cross-section flexural capacity calculation are put forward by using limit equilibrium theory.The formula is expressed clearly, simple and easy to use.The depth of compressive region is given in view of different failure types.

Abstract: This paper presents the tensile membrane action on one-way reinforced concrete slabs, and two full-scale specimens with one edge clamped and one edge simply supported were tested at large displacements. The details of the two tests including support conditions, arrangement of reinforcements and layout of displacement transducers are described. The test results show that the load-carrying capacity of the two slabs is significantly improved due to the tensile membrane action, about 26.6% more than the predicted value using the well-established yield-line theory. Until maximum vertical displacement reached 1/15 of the span-length, the slab did not fail and carried the load steadily.

Abstract: The conventional methods used in the design of sheet-pile walls are based on the limit equilibrium approach. Due to a flexible retaining system, the choice of soil pressure needs to be further studied. Test about sheet-pile wall was carried out on typical site. Soil pressure distribution rules on horizontal and vertical direction were revealed by comparing the on-site measured and numerical data with classical soil pressure data. The results show that: the soil pressure resultant force of anchored sheet-pile is close to static soil pressure, and its action point is 0.43~0.44, higher than the static soil pressure (0.33). The resultant force and its action point of soil pressure of cantilever sheet-pile wall are close to the ones of coulomb soil pressure. In horizontal direction, there present “arching effect” on this two kinds of sheet-pile walls. Therefore, the current soil pressure calculation methods of sheet-pile walls should be revised according to different types, and an amended calculation method of soil pressure was proposed in this paper.

Abstract: This paper put forward a new concept named equivalent guarantee rate, which can be used to evaluate the crack control safety level in concrete design specification more conveniently. As a numerical example, the crack control safety level for civil buildings in GB 50010-2010 “Code for Design of Concrete Structures” is analysized by calculation of equivalent guarantee rate and fuzzy reliability index respectively. The rationality of equivalent guarantee rate is confirmed by comparing the calculation results of the equivalent guarantee rate and the fuzzy reliability index.