Applied Mechanics and Materials Vols. 501-504

Abstract: Numerical simulations the different rock sample in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA^2D) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.

Abstract: With the development of offshore oil and gas field, subsea production system has become an important mode in the deepwater development. Underwater manifold and structural framework have played a crucial role in the underwater system. The article describes the stress analysis of submarine framework based on Inventor. And the paper studies the change of framework about stress and displacement on the normal operating condition. The method ensures that the frame structure has met the design objectives and requirements. Meanwhile, it has played a key role on the submarine structure researching and provided effectively reference for the future designing.

Abstract: The internal forces in a prestressed concrete structure are of special nature due to the existence of tendons. And flaws can be found in the traditional concept of secondary moment such that common computation method of secondary moment may produce unreasonable results. This article aims at getting a better understanding of internal forces in prestressed structures and solving the relevant problems. Starting from the basic principles of internal force analysis, a new system of internal forces is put forward by which the relationship between the compression resultant on concrete cross-section and the sectional internal forces is made clear. On this basis, a definition on the concept of current secondary moment (M_cs) is proposed and its superiority pointed out. Finally, theoretical analyses are carried out on the method for calculating M_cs in the posttentioned continuous beams with unbonded and bonded prestressing tendons.

Abstract: The thin-webbed I-shaped members are used as the basic members for beams and columns of steel buildings in order to increase utilization ratio of steel. The local buckling can occur for these members because of the large width-thickness ratio and these members have a substantial post-buckling strength which can be used. Different codes in China have different estimation method for substantial post-buckling strength of thin-webbed I-shaped members. So it is very necessary to establish the same calculation method to consider post-buckling strength for different china codes. In this paper the effective width estimation methods of technical specification for steel structure of light weight buildings with gabled frames (CECS 102-2002), code for design of steel structures (GB50017-2003), technical code of cold-formed thin-wall steel structures (GB50018-2002), America specification (AISC: 2005), European specification (E3-1.5:2006), and Winter equation are introduced simply. The effective area of thin-webbed I-shaped members with different width-thickness ratio in web and slenderness ratio are estimated using these codes. Comparison of these estimated results show that CECS 102-2002, GB50017-2003, AISC: 2005, Winter equation, and E3-1.5:2006 may be conservative or unsafe for members with different slenderness ratio or width-thickness ratio of web. GB50018-2002 is applicable for members with different slenderness ratio or width-thickness ratio of web without considering interaction between flange and web of members and can be used to estimate the effective area of thin-webbed I-shaped members. At the same time, the calculated method of post-buckling strength of thin-webbed I-shaped members in CECS 102-2002 and GB50017-2003 could use the same method as GB50018-2002.

Abstract: The paper adopts large deformation elastic buckling finite element method, researches the out-of-plane stability of lateral braced web openings circular steel arches under the distributed radial load and considers the effects of rise-span ratio, arch foot condition, brace rigidity and brace quantity. Research results demonstrate that the out-of-plane buckling load of web openings circular arches increases with the rise of rise-span ratio and increases with the improvement of arch foot constraint. Buckling half waves increase gradually with the increase of lateral brace stiffness. When brace stiffness reaches the brace critical stiffness, the out-of-plane buckling load of steel arches increases will no longer increase with the rise of the brace stiffness, and the buckling mode of steel arches will transit from out-of-plane instability to in-plane instability. The improvement degree of lateral brace to the bucking load of web openings circular steel arches depends on the lateral brace quantity and the size of the brace intervals.

Abstract: This article deals with the condition that the roof beams of portal frame are outward offset beyond the standard limit, determines the most unfavorable position of the portal frame structure under the load and establishes the criterion standard of structural failure based on the space overall finite element analysis. It adopts Monte-Carlo method in reliability analysis methods to realize the overall reliability analysis of the portal frame structure with the roof beam outward offset. Analysis shows that the actual structure is at safe state under the design load and the reliability conforms to the standard requirement.

Abstract: This article analyses the reliability of portal frame based on space overall ultimate bearing capacity. A double nonlinear numerical model is established according to the finite element software ANSYS to track the space overall ultimate bearing capacity of the structure and to make clear the failure modes of the structure. The article studies and discusses the reliability of the portal frame based on space overall ultimate bearing capacity, gets the range of the structural reliability index and the sensitive degree of each parameter on the reliability, and presents the measures to improve reliability.

Abstract: The superstructure and foundation of highrise are in a complete system of interaction. Taking the case of project, by comparatively analyzing the computed value which is calculated by applying the theory of interaction between superstructure and foundation and the measured value ,we find that the computed value neatly dovetails with the measured value.

Abstract: In paper describes a method of optimization the stress state of an elastic beam, subjected to the simultaneous action of the central application of concentrated force and bending moment. Optimization method based on solving the inverse problem of the theory of elasticity of inhomogeneous bodies, the essence of which is to determine the law of changing the modulus of elasticity on the beams height for which stress state will be given.

Abstract: Horizontal fibers of the outer layers of composite foam sandwich tube affected the compressive capacity of the tube under axial load. In order to clarify the strain distributions when the horizontal fibers of the outer layers were pulled off, dynamics finite element software LS-DYNA was used to simulate the model. Variation of hoop strain and axial strain of elements were observed. The simulation showed that the hoop strain of the composite tube increased gradually from the bottom and became the maximum in the middle of the member, which caused the pull-off damage and agreed with the test results. Strain along the circumferential direction of same height on the tube was average, and the same to the axial strain.