Advanced Materials Research Vols. 163-167

Abstract: Based on the characteristics of expansive soil and polyethylene fibers used and researched, relevant data of fiber improving expansive soil are obtained by laboratory soil tests, and the numerical simulation parameters are derived by some formulas, through the useing of Mohr-Coulomb and elasticity constitutive model of the geotechnical professional software FLAC3D, we simulate the effect of polyethylene fibers improving expansive soil. Results of laboratory tests show that polyethylene fibers have visual effects on the compressibility and compression modulus of expansive soil ; Numerical simulation shows that the polyethylene fiber soil of expansive soil can reduce the settlement and horizontal displacement of roadbed of expansive soil significantly. Both of them show that fiber materials have high value of the promotion and application in engineering.

Abstract: Sunflower-patterned cable dome which gets stiffness by prestress tensioning and force self-balance is a kind of cable-strut spatial tensile structure. If distribution of prestress in each layer of the structure is appropriate in construction, its deformation under vertical loads will be uniform. In finite element analysis software ANSYS, principle and method of selecting the optimal prestress distribution of sunflower-patterned cable dome were obtained through applying several different kinds of prestress on each layer of loop cable in calculation model and analyzing its deformation uniformity under full-span load respectively.

Abstract: Study on the reliability of H-beam transfer truss was based on the rebuilding of 1# office building of Chinese Ministry of Commerce. Under construction loads, the force analysis of the H-beam transfer truss was carried out with the software STS2005.12. In the paper, the right of trusses node connection was first chosen, and a plane calculation model of H-beam transfer truss was established based on some reasonable assumptions. Then, the force of H-beam transfer truss under construction loads was analyzed with the calculation model, in determining a reasonable control indexes and calculation parameters. From the results of analysis, we could see that the design and application of H-beam transfer truss in the stage of construction was safe and reliable, in the dismantling concrete post of old structure.

Abstract: In order to look into the causes of fire response and post-fire bearing capacity of the steel tubular columns protected with different materials, the fire test was conducted for a set of circular steel tubes protected with different materials such as gypsum fireproof panel, bamboo plywood and the ordinary lumber core plywood, and the steel tube without any protective material. The fire response temperature of surface of steel tubes is measured and the axial compressive bearing capacity of the specimens after fire are tested and analyzed. The test results show that gypsum fireproof panel has the best fire protection characteristics, the ordinary lumber core plywood and bamboo plywood can also retard rising of the surface temperature of the steel tubes during the initial 35min although they are combustible materials. It is found that the post-fire bearing capacity of the steel tubes protected with different materials varies evidently, and the maximum value of response temperature has the greatest effect.

Abstract: Suspen-dome is a kind of large-span prestressed hybrid structure, To understand the influence of radial restraining stiffness to structural mechanical response, and to ensure radial restraining stiffness reliable during designing, a rib 3 type suspen-dome and corresponding single layer lattice shell were selected, their static response under different radial restraining stiffness were studied and compared .At the same time, basic dynamic properties of a rib 3 type suspen-dome were analyzed under different radial restraining stiffness. The results show that the sensitivity of single layer dome mechanical response to radial restraining stiffness will be reduced because of the bottom cable-struts, enhance of radial restraining stiffness will not influence structural mechanical response after radial restraining stiffness reaches certain value.

Abstract: A second-order inelastic analysis of semirigid connection steel frame structures is developed. Therein, shearing deformation and axial force simultaneously are considered. A new stability function considered shearing deformation and axial force simultaneously is proposed and the analysis methods for steel structure of semirigid connection based on the structural ultimate bearing capacity are established. The calculatical programe of second-order inelastic analysis semirigid connection steel frame structures is compiled. The numerical examples of steel frames for semirigid connection are analysed using the second-order inelastic analysis in the paper. Load–displacements predicted by the proposed analysis compare well with those given by other approaches. The analysis results show that the proposed method is suitable for adoption in practice.

Abstract: The influence of superabsorbent polymers (SAP) as internal curing stuff on the restrained shrinkage and cracking of concrete was investigated. Results show that SAP in the mortar with slag and silica fume increases the compressive train of the steel ring, but postpones the initial cracking time of the mortar from 5 days to 6.5 days and reduces the crack width by 25% at age of 28 days.

Abstract: Trimethylchlorosilane as a modifier and tetraethoxysilane, an acid catalyst, as raw material were modified hydrophobically through the copolymerization, surface derivative, and hierarchical hydrophobic modification methods. The modified material was prepared as hydrophobic SiO₂ aerogels by constant pressure drying. Finally, thermal stability, pore structure, and chemical composition of SiO₂ aerogels were analyzed using TG-DSC, FTIR, and BET. The results show that the hydrophobic property of SiO₂ aerogels prepared using hierarchical hydrophobic modification and surface derivative methods have excelled characteristics, such as super-hydrophobicity. The aerogels prepared through the two different methods have a mesopore structure with mesopores of 2–70 nm; however, they have no micropore structure.

Abstract: 8 plate-reinforced connections are manufactured at 1/2 scale and then tested under low-cyclic loadings to study their hysteretic behavior, and numerical simultation with ANSYS are applied based on the experimental results. Failure patterns, energy dissipation, hysteretic behavior and skeleton curves are comparatively studied by changing the dimensions of the reinforced plates. Results show:(1)the plastic hinge be formed 1/3-1/4 beam depth from the end of reinforced plate and is obvious, there are serious local buckling in the flange and web, and there is no fracture in the beam-to-column welding;(2)The geometric parameters of reinforced plate have important effect to the bearing capacity and ductility of connections. With the increase of length and thickness of reinforced plate, the bearing capacity increases and hysteretic behavior and ductility factor decreases;(3)When the length of reinforced plate is bigger than the design requirements, there is brittle failure in the panel zone, which lead to decrease of capacity of energy dissipation and equivalent viscous damp coefficient;(4)Recommended parameter scope: the recommended length of reinforced plate(flange-plate and cover-plate) is defined as 0.5-0.8 times beam depth, the recommended thickness of flange-plate is 1.2-1.4 times flange and the recommended thickness of cover-plate is 0.7-1.2 times flange.

Abstract: Pre-stressed steel structures with large space are widely used in stadium, exhibition hall, theater and other buildings today. In order to study the fire-resistance behavior of suspended steel lattice shell of a stadium, the method of performance-based fire resistance design is used. First of all, the stadium physical model is established and the software FDS is used to determine the heating curves of the measuring points of the large space structure for two fire scenes. Compared with international standards heating curve, the heating curves of the large space structure obtained here has characteristic of local high-temperature. The finite element software MSC.MARC is further used to simulate the fire behavior of the pre-stressed steel structure with large space, in which the fire scene with 10MW design power of fire source and 30 minutes duration of fire are considered and two loading ways that overall non-uniform temperature field loading and the local high temperature components loading are accepted. The results show that the pre-stressed steel structure with large space has good fire resistance behavior, and the overall failure will not take place for the fire scene suggested here during 30 minutes duration of fire.