Advanced Materials Research Vols. 163-167

Abstract: Based on the appropriate numerical constitutive model of concrete filled steel tubes, layered method was applied and fiber model method based on partial sinusoidal shape for concrete filled circular steel tubular (CFST) columns under both concentric and eccentric loading was proposed. Utilizing the relationship between the curvature of the worst section and sinusoidal amplitude, a FORTRAN program was developed and the behavior of CFST columns under concentric loading, eccentric loading of equal end-moment and unequal end-moment were analyzed, showing that the analysis results are in good agreement with the experiment results from references and the fiber model method can reflect the load capacity and deformation of the columns reasonably. Thus the reliability of the present method was validated and this work is the basic for the further researches on the practical expressions of load bearing capacity for the CFST columns under both compression and bending.

Abstract: Based on the pseudo-static test of 6 high-strength RC columns with central reinforcement skeletons, this paper studied their hysterisis performance, degradation of strength and rigidity, and energy dissipation capacity, with the affecting factors analyzed. The result shows that the central reinforcement skeletons can compensate for the low plasticity and brittle failure susceptibility of high-strength concrete so that all the specimens have stable strength, slow rigidity degradation and high energy dissipation capacity at later stage of loading; the larger the core areas the higher the strengths and ductility of the specimens, but slightly faster the degradation of strength and energy dissipation capacity as compared with the specimens with smaller core areas; the spacing of ties, longitudinal reinforcement ratio of core area both influence the strength degradation and energy dissipation capacity of the specimens, but they have little effect on their strengths.

Abstract: The uniform design standard of temporary support structure in building construction has not been published, In case of coupler steel pipe support system, characteristics for the temporary support structure, the standard structure of the system is proposed. It is suggested that the design of temporary support structure should be combined with the present theory of the design of steel structure. The design method of temporary support structure based on equivalent notional lateral loads is proposed. The formula is given, which is verified by tests and is compared with the formula recommended by the present code. The result shows that the formula can meet the requirements of the safety factor, which provides a reference for those concerned with research, design or construction.

Abstract: A typical rib-to-deck joint in orthotropic steel bridge deck in a suspension bridge is analyzed in this paper. A local finite element model of bridge deck is established by ANSYS, the vehicle load defined in current code is selected as live load, the stress distribution of the deck bottom in the rib-to-deck joint is analyzed. Let the wheel load move along the longitudinal direction of the deck, the maximum stress range at rib-to-deck joint is obtained under three loading conditions in transverse direction, which are riding-rib wall loading, over-rib loading, and in-between-ribs loading respectively. Using the principles of linear elastic fracture mechanics, the fatigue life of rib-to-deck joint in orthotropic steel decks is evaluated. The analysis results indicate that, the higher stress range under overweight wheel load is the basic reason which will induce fatigue crack at rib-to-deck joint. The Paris formula which is based on the linear elastic fracture mechanics can be used to estimate the residual life of weld joints in orthotropic steel bridge deck.

Abstract: The tests on thirteen specimens of casing joints of square steel tube were conducted to investigate the flexural behavior of the joints. And numerical simulation studies on that were carried out by ANSYS/LS-DYNA. On this basis, effects of tube wall thickness, tube edge length, and inserting depth on failure mode, ultimate flexural capacity and deformation of the joints were discussed. The results show that there are two types of failure modes, i.e., inside tube yield failure and outside tube shear failure. Ultimate flexural capacity and rigidity of the joints increased with the inserting depth increasing. The ultimate flexural capacity is proportional to tube shear strength, tube wall thickness, inserting depth, and tube edge length.

Abstract: This article focuses on the construction of portal frame without crane. The dynamic variational laws of the additional internal force and displacement of the portal frame construction under the elongation, compression, tilt (uneven settlement), positive curvature and negative curvature deformation of ground are calculated by numerical simulation method, using the structural finite element analysis software – ANSYS. We find that the swing column will alter the distribution of the frame construction additional internal force with the surface deformation; and it can effectively restrict additional deformation of the beam, which is caused by the surface deformation. The swing column increased the ability of resist surface deformation of frame construction with compression and uneven settlement deformation; but it reduced the ability of resist surface deformation of frame construction with elongation deformation. Moreover it indicates that the reciprocity between base and foundation will alter the distribution of the frame construction additional internal force with the surface deformation.

Abstract: Position deviation of joints is a primary initial geometrical imperfection that affects the stability of long-span spatial structures. It makes field measurement of joint coordinate for the shell and roof initial shape of Nantong Sports Exhibition Center upon its completion. This paper researches the stochastic distribution feature and statistical parameter of geometrical imperfections for the data sources of above position deviation of joints by “abnormal data test method”. The results indicate that the distribution of abnormal data is concentrated, which is related to the difficulty of construction and condition of measurement; the distribution of joint position deviation can be assumed by normal distribution, and its mean μ=0 and mean square deviation σ=R/2 of statistical parameter are tenable. Meanwhile, It also puts forward a stochastic imperfection method based on measured imperfections and ANSYS－PDS platform, establishes a measured model to make nonlinear stability analysis, and respectively compares this critical load with that obtained by the perfect structure of ideal shape and the consistent imperfection method, so as to evaluate the stability and reliability of practical project in an objective manner, and provide reference for project design.

Abstract: To obtain a better understanding of the behavior and load-carrying capacity of Q460 high-strength single-angle compression members bolted by one leg, using static loading way to 48 angles carried out experimental study. The experiments show test specimens produce biaxial bending, most small slenderness ratio members are controlled by local buckling, and slender specimens are controlled by overall buckling. In addition to these factors in model experiment, influences of residual stresses on ultimate load-carrying capacity were analyzed by finite element numerical simulation analysis, the results show the residual stresses affect the ultimate load-carrying capacity of angles by about 5％ or less. Comparison of the load-carrying capacity of experimental and theoretical results indicate the difference of experimental and finite element values ranges from -9.99％ to +9.76％, American Design of Latticed Steel Transmission Structure (ASCE10-1997) and Chinese Code for Design of Steel Structures (GB50017-2003) underestimate separately the experimental load-carrying capacity by about 2.34％～33.93％ and 1.18％～63.3％, and the agreement is somewhat good between experimental program and the finite element analysis. Based on model experiment and simulated experiment, the formula of stability coefficient of single-angle compression members was established. It provides basic data for spreading Q460 high-strength single-angles members attached by one leg.

Abstract: Joint’s stiffness has important influence on the stability behavior of large-span spatial reticulated shell. In this paper, the nonlinear beam-column element with end springs is taken as the analysis model of members of single-layer reticulated shell, the whole process of nonlinear stability for single-layer reticulated shell is analyzed with the software ANSYS, the influence of joint’s stiffness on the stability of single-layer reticulated shell is studied. Some important conclusions were obtained, which can provide theoretical foundation for the stability ultimate bearing capacity analysis of large-span spatial reticulated shell considering joint’s stiffness and can be applied on practical design.

Abstract: The seismic performance spectrum is a new kind of the response spectra which is formed according to the designated performance objectives. The performance objectives are changed according to the performance objective level and period of structure, and are different in the acceleration sensitive, velocity sensitive and displacement sensitive range in the seismic performance spectrum. The seismic performance spectrum formulas are derived, which demonstrate the mathematic relationship between the seismic demands of the different performance objective levels and the period of structure. The fitted formulas of the seismic performance spectra for seismic design are obtained due to statistical result of 1085 ground motion records. The new seismic performance spectra are shown in visual three-dimension figures which can represent the seismic demand, performance objective and period of structure in this paper. The philosophy of the seismic performance spectrum is analyzed which reveals the rules for estimating seismic demand of structure at the different performance objective levels. So the multi-objective performance-based seismic design is also proposed using the seismic performance spectrum.