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In this study, cyclic tension tests were conducted on ordinary Galfan cables and locked coil Galfan cables with diameters of 40 mm to evaluate their mechanical properties under cyclic tension. The mechanical behavior of the two kinds of Galfan cables under monotonic loading and cyclic tension was analyzed, while the differences in strength and the mechanical properties of the two kinds of Galfan cables and the effects of different loading systems on the mechanical properties of the two kinds of cables were obtained. The Ramberg–Osgood model was used to fit the skeleton curve. The elastic and inelastic behaviors during loading and unloading were studied. The change in elastic modulus of the Galfan cable with respect to cyclic load is proposed, and the exponential model of strain and elastic modulus under cyclic load is established, which lays a foundation for the accurate finite element analysis of cable structure response under strong earthquake and other accidental loads. [ABSTRACT FROM AUTHOR]

PVC-coated polyester fabric is a widely used building material whose tearing strength is much lower than its tensile strength. Extreme loads such as fire, unexpected winds, or hail may cause cracks in the membrane. The tearing properties of PVC-coated fabrics were researched in this paper. Tensile tests with precracked specimens and tongue tear tests are the two most commonly used methods to research the tear strength of coated fabric membranes. The tearing properties of coated fabric membranes at high temperature were researched by tensile test with precracked specimen. Refined finite-element (FE) models with yarns were built and verified according to the experiment. The effects of initial crack length, off-axis angle single-yarn cross-sectional area, and coating thickness on the tearing properties of coated fabric membranes were studied. With the increase of temperature, the tear strength of a coated fabric membrane decreases significantly. The theory of linear-elastic fracture mechanics is still applicable to coated fabric membranes, and the sensitivity of a coated fabric membrane to crack length is lower than that of homogenous materials. The tensile mode stress intensity factor (SIF) of the coated fabric decreased only by 15.2% with the crack length increasing from 0.2 to 0.6 times the specimen width, whereas the tensile mode SIF of a homogenous material decreases by 66.5%. Coated fabrics with thicker yarns have higher tear strength and smaller fracture displacement. The strength of a coated fabric increased 53% and the section area of single yarn increased by 2.5 times, but the total section area was not changed. The allowable tearing stress of membranes with internal and edge cracks based on fracture mechanics and design code were proposed. [ABSTRACT FROM AUTHOR]

Net radiation is an important and site-specific component to determine reference evapotranspiration ([ET.sub.0]). The empirical Angstrom coefficients for radiation estimation in the FAO56 Penman-Monteith (PM) equation were calibrated using observed daily solar radiation and actual sunshine duration on the Tibetan Plateau. The calibrated Angstom coefficients included annual coefficients for nine meteorological stations separately and aggregation of nine stations. The calibrated annual coefficients for each station separately were applied to estimate net radiation and further employed to estimate [ET.sub.0] using the PM and the Priestley-Taylor (PT) equations on the Tibetan Plateau. Moreover, the Hargreaves (Harg) equation that requires only air temperature was also applied to estimate [ET.sub.0]. Comparisons of three methods were conducted and the results showed that the PT method overestimated daily [ET.sub.0] with respect to PM-[ET.sub.0] and the Harg method underestimated it at all meteorological stations. The PT method was more suitable for the study area in the absence of the parameters necessary for the calculation of PM-[ET.sub.0]. The Harg equation provides [ET.sub.0] estimates when only air temperature is available and local calibration in the study can be applied on the Tibetan Plateau. CE Database subject headings: Statistics; Evapotranspiration; China; Solar radiation; Coefficients.

This paper puts forward a new kind of joint called plate-insert welded tubular joint that is used in long-span prestressed spatial structures. It is composed of one inserted plate, one major member, and several minor members. The plate is inserted through a major member, and the minor members intersect the major member. The static performance of cooperative work between the inserted plate, major member, and minor members are studied by numerical analysis using ABAQUS and Ansys, from which the elastic ultimate bearing capacity of the joint are obtained. The multigroup of geometric parameters are set to establish a number of finite-element models for parametric analysis to obtain the effect rule of different inserted-plate length parameters on bearing capacity. Then a new design method of the joint is put forward on the basis of the analysis. From the joint design example of the second stage of the Tianjin Binhai International Exhibition, the reliability of the method is verified using a combination of numerical and experimental studies. [ABSTRACT FROM AUTHOR]

Most previous stress relaxation tests were based on steel wires and steel strands. This test performed 1,000 h of stress relaxation test on stainless steel cables and Galfan-coated steel cables with diameters of Ø14 , Ø20 , and Ø26 mm. Three different initial tension levels were tested, and three control values of 30%, 50%, and 70% of the ultimate tensile strength of the cable were used as the load control points. The stress relaxation tests were carried out in a factory building, and the temperature was not strictly controlled. The stress relaxation of the cable is the stress relaxation under the combined action of temperature relaxation, stress relaxation, and time relaxation. To make the research more valuable, the thermal expansion coefficient of the cable was used to eliminate the influence of temperature on the stress relaxation test, and the data were adjusted to correspond to 30°C. The test results were analyzed, and formulas for calculating the tension loss of steel cables were established. The results showed that the exponential equation of time logarithm can better express the relation between tension loss and time. The relation between the coefficients and the initial tensile force was established. This test also compared the relaxation properties of stainless steel cables and Galfan-coated steel cables. For steel cables with the same initial tension level and the same diameter, the Galfan-coated steel cables had much larger relaxation rates than the stainless steel cables. [ABSTRACT FROM AUTHOR]

Steel cable is the key component of prestressed steel structures. However, the thermal expansion coefficients of steel cables have not been adequately evaluated yet. This paper presents an experimental study on this topic. A total of 15 groups of specimens were tested, including steel-wire rope cable, steel strand cable, semiparallel steel tendon cable, and steel rod. The thermal expansion coefficients were measured by a manufactured testing instrument. The examined coefficients of the cables were 1.92×10-5, 1.38×10-5, 1.87×10-5, and 1.195×10-5/°C, respectively. Subsequently, a cable-supported beam was further numerically analyzed considering temperature effects. The numerical results showed that temperature has a significant effect on the mechanical behavior of the beam when either steel-wire rope cable or semiparallel steel tendon cable is employed. When steel strand cable is adopted, the temperature effect is moderate. For steel rod, the effect is less. Therefore, the influence of prestress losses because of temperature changes should be considered for different types of steel cables in practical design. [ABSTRACT FROM AUTHOR]

Different countries adopt different values of thermal expansion coefficients for steel cables in their design specifications, which results in the inconsistency for the design of prestressed structures. Therefore, a systematic study was conducted analytically and experimentally on thermal expansion mechanism of steel cables in this paper. First, the thermal expansion mechanism of steel cables was proposed, and the evaluation approach on the linear thermal expansion coefficient of steel cables was developed. The study identified the parameters that significantly affected the thermal expansion coefficient. After that, six types of steel-wire rope cables were tested by a thermal expansion coefficient measuring instrument. The identified parameters of the thermal expansion coefficient for these steel-wire rope cables were examined to show the effectiveness of the proposed approach. The analytical analysis further showed that the linear thermal expansion coefficients of these steel cables decreased with the lay pitch of the steel wires increasing, but the coefficients increased with the diameter of the steel wires increasing. Because the explicit expression of the analytical formula for the thermal expansion coefficients was very complicated, an advanced nonlinear finite-element model (FEM) was established to evaluate the thermal expansion coefficients of steel cables under idealized conditions by using the ANSYS software package. The analysis showed that the test result, the analytical result, and the numerical result were consistent, which exhibited that the FEM was effective to simulate the expansion of steel cables. In addition, 14 types of steel cables were tested. The tested steel cables included steel-wire rope cable, steel strand cable, and steel tendon cable. The thermal expansion coefficients were as follows: the steel-wire rope cable was 1.92×10-5/°C; the steel strand cable was 1.38×10-5/°C; the steel tendon cable was 1.87×10-5/°C; and the steel rod was 1.19×10-5/°C. The analytical and experimental results can provide a guideline for the relevant study on prestressed structures. [ABSTRACT FROM AUTHOR]