Applied Mechanics and Materials Vols. 638-640

Abstract: To consider the contribution of the floor to the flexural capacity of frame beams, slabs are usually equivalent to floor "effective flange width" . However, there are no academia acknowledged conclusions about the value of effective flange width was drawn. This article introduced the theories about the calculation of "effective flange width" and studied the influence of node type to the value by comparing various MIDAS simulation models. Finally, we concluded suggested formulas after combining the analysis and experimental results.

Abstract: When the long-distance oil pipeline under rivers (referred to as river-crossing pipelines) are damaged by the third-party, they are prone to nudity or left vacant, and the oil pipelines under the action of water flow will cause pipeline failure; and the distance of suspended pipeline is longer than the allowed length will cause the pipeline resonance. In order to avoid pipelines fatigue or broken, suspended pipelines are considered as part of the arc shape, and non-suspended pipelines are considered as the linear shape of the mechanical model with the two ends of the fixed pier synchronous. The study will consider the impact of water flow, buoyancy, the gravity of pipelines and its annexes, bending deformation and bending moment, do the tense calculation for suspended pipelines with external load and the vibration analysis for suspended pipelines under different water flow speeds. The results showed that: the design of river-crossing suspended pipelines not only needs to consider the impact of water flow, buoyancy, the gravity of pipelines and its annexes, bending deformation and bending moment, but also to consider the floating vortex-induced vibration of the suspended pipeline, which should cause pipeline designers, constructors and maintainers’ attention.

Abstract: As the study of the dynamic response of single-layer reticulated domes under impact, Numerical models for single-layer Kiewitt-6 reticulated domes with sub steel cube column were established by the ANSYS/ LS-DYNA program and a dynamic analysis were carried out. Four failure modes for the reticulated domes were put forward according as the dynamic response and plastic deformation. The parametric analyses on the dynamic response of single-layer reticulated domes with sub steel cube column under the impact loading are carried out, by changing the impact velocity, mass of impact object, size of impact object and impact location.The effects of these parameters on the response mode of the structures are investigated, and the distribution regularity of the response modes of the structures with different parameters is explained.

Abstract: Research of influence of fire impacts on the dynamic strength of eccentrically compressed concrete elements requires a deeper consideration. The purpose of this article is the study of dynamic strength of eccentrically compressed concrete elements in fire conditions under rapidly increasing dynamic loading. It is done the analytical calculation of eccentrically compressed reinforced concrete columns under different thermo powers conditions, there are shown the results of calculations and experimental data. It is shown a graph of dynamic coefficient for concrete depending on the time of dynamic loading and temperature.

Abstract: In elastic fracture mechanics the evaluation of the stress intensity factor (SIF) for multiple cracks problems is an important issue. In the paper the scaled boundary finite element method (SBFEM) is used to solve the SIF of mode I of multiple crack problems. The solving domain is partitioned into several sub-domains according to the number of cracks. Every sub-domain has its own scaling center. The characteristics of the SBFEM are preserved in every sub-domain. Numerical examples show that the SBFEM is effective with high accuracy in evaluating the multiple cracks fracture problems. It can be applied to treat the anisotropic materials conveniently. The stress intensity factors of unequal double-edged cracks in orthotropic material are provided.

Abstract: Two thermal experiments of light gauge steel-framed composite walls with slotted studs and with external thermal insulation layer were carried out in the lab of combined energy consumption test board for components of building envelope in school of municipal and environmental engineering at Harbin Institute of Technology (HIT). The lab is one of the key laboratories of Ministry of Housing and Urban-Rural Development of the P.R.China. The method of thermocouple temperature measurement has been used. The heat transmission coefficient and the measuring point temperature of composite wall have been deeply investigated, which is finely compared with the FEA model results at the same time. Two conclusions can be drawn from the test: web slotted studs can reduce heat loss of the light gauge steel-framed composite walls obviously, thus it can weaken the thermal bridge effect of the location in stud part, so it can improve the thermal insulation properties of the composite walls significantly; the composite walls’ heat transmission coefficients of the two test schemes go to: 0.315W/(m²·K) and 0.250 W/(m²·K), which can meet the residential building envelope heat transmission coefficient limit value in the cold areas of China well.

Abstract: Both experimental research and theoretical analysis of ultimate strength for steel tubular tower joint are developed. The experimental data comprise four different specifications of steel tube, that is, without ribbed plate, with 1/4 annular ribbed plate, with 1/2 annular ribbed plate and with annular ribbed plate. This paper considers that the ultimate strength of steel tubular joint depend on the following four parameters, that is, the ratio of length of joint plate to outer diameter of steel tube B/D, outer diameter D, axial force and ratio of length of annular plate to outer diameter of steel tube R / D as well as the ratio of thickness of annular plate to thickness of steel tube. Furthermore, a recommended formula of the ultimate strength of steel tubular joint is derived by the potential energy principle and the principle of virtual work in elasticity and plasticity based on the failure modes of experimental specimens. It is demonstrated that the applicability of the recommended formula is better.

Abstract: With the rapid development of power transmission and transformation projects in China, steel supporting structure has already became the most popular structural form for these structures. However, the limit of steel grade used for current substation supporting structures is normally Q420, compared with that of Q690 used in other countries. When the high-strength steel is used, the geometric parameters of section for members become smaller, and the stability of members is the most important factors to influence the bearing capacity of structures. The stability factor for axial loaded steel members in current 《Code for design of steel structures》(GB50017-2003) was derived based on the experimental results for steel members with lower steel grade, the results are inevitably different from those for high-strength steel members. To make the calculations of Q690 high-strength steel tubes more accurate and reasonable, this paper conducts experimental study on the bearing capacity of Q690 high-strength steel tubes under axial load to provide scientific basis for practical design of these structures.

Abstract: Transmission lines pass through various types of regions in China and some of that are corrosive. The foundation concrete of transmission lines in corrosive environments had shown serious deterioration, which usually caused by concrete deterioration, rebar corrosion, degradation of bond strength between rebar and concrete due to various corrosive effects. There are salt lake areas in west China where some power transmission channels pass through. Field tests are carried out in Golmud area to research the durability of foundation concrete of transmission lines. And test results show that the concrete strength in the air is higher than underground and the carbonation depth of the foundation concrete decreases with the increase of concrete compressive strength.

Abstract: Mechanical properties of joint between superimposed slabs have a remarkable effect on the bending performance of the whole slab. To study the bending performance of superimposed slabs with different forms of joint, six superimposed slabs were designed and produced. Based on the static loading experiment, load was concentrated on two three-equal-division points, bearing capacity, deformation, cracks of specimens were obtained. Whether there were lattice steel bars in the precast slab or not and different reinforcement in the joint were considered to study the bending performance. The test results show that the failure mode of slab without lattice steel bars is brittle while others are ductile. Lattice steel bars can control the development of cracks along the superposed surface, increasing the shear capacity and improving the ductility of specimens. The bearing capacity of the whole superimposed slab depends on the joint cross section. The joint would not generate a difference to the deflection curves in service condition. When reinforcement in the joint is strengthened, failure modes of slabs will be effectively improved.