Advanced Materials Research Vols. 446-449

Abstract: The balanced reinforcement ratio of FRP-reinforced concrete members and the flexural capacity under two different failure modes (concrete crushing and FRP rupture) are established, based on the analysis on flexural capacity of steel-reinforced concrete members in current concrete code. The effect of material properties on the balanced ratio, the variation of flexural capacity with different reinforcement ratio and a simplified nominal flexural capacity under FRP-rupture failure are derived.

Abstract: Progressive collapse is defined as total or remarkable partial collapse of structure following the damage occurred at a small portion of the structure. In most cases, the study is focused on progressive collapse of structures due to explosion, vehicle impact, fire and other man-made hazards; with less attention on progressive collapse mechanism of structure due to earthquake. Although the post earthquake inspections show that structural elements, mostly columns in the corner of the plan, can be severely damaged during earthquake. If neighboring columns are not properly designed to resist and redistribute the additional gravity load that is imposed by the column loss, partial collapse of the structure will occur; which would lead to progressive collapse of the structure. In this regard, progressive collapse potential of a moment resisting steel building is investigated via analytical procedure under earthquake action. In this research, a corner-column of the building was weakened intentionally to navigate the damage toward a certain part of the structure. Then, nonlinear static analysis is carried out on the three dimensional model of the building and the total behavior of the structure is studied. The results indicate that after the failure of the corner-column, the lateral resistance of the frame in which the removed (failed) column was located decreases, and the failure of the other columns occurs. Large plastic deformations and the failure of the other members could cause progressive collapse in the whole structure and the expected ductile behavior of the structure would not be observed.

Abstract: Pre-stressed reaction wall is an important test facility in structure laboratory．Reaction wall will bear large static and dynamic loads when working, so pre-stressed concrete structure is often used. A model of micro-concrete pre-stressed reaction wall is made in the test in order to insure tension quality of steel strand of reaction wall. Proposed 4 different tension schemes of reaction wall pre-stress rebar, and a comparative study on the variety trend and distribution of strain on reaction wall in the 4 different schemes．The experimental results show that the best schemes of tension pre-stress rebar is：use the wall cross-section center of gravity as the symmetric point, tension symmetrical up and down from central to outside．And we suggest that two times or supplement tension methods be use to stretching steel strand of reaction wall.

Abstract: Abstract. The limit state equation of the shear capacity with earthquake action effect combination is presented, and the statistical parameters and probability distribution of the representative value of gravity load and earthquake action effects in the limit state equation are discussed, in which, the representative value of gravity load complies with normal distribution, while the earthquake action effect complies with extreme value type-I distribution. By statistics on the test results of broad-limb special-shaped columns under repetitive-loading, indefinite coefficient statistical value on calculation model of shear capacity formula of broad-limb special-shaped columns is obtained, and then JC method is adopted to make a reliability analysis on the calculation formula. It is shown from the results that the formula is safe enough in calculating shear capacity of broad-limb special-shaped columns.

Abstract: In petrochemical industry, single layer dome steel structure is usually used to support dome roof in cylindrical tank. This paper takes a dome steel structure with a diameter of 52m（type Kiewitt）designed by a petrochemical corporation of Lianyungang as an example. According to the People's Republic of China industry standard JGJ61-2003, utilizing Arc-Length method of the finite element analysis software Abaqus to analyze this example’s overall non-linear geometry, and utilizing finite element increment iteration to analyze this example’s response during the whole loading, we obtain the instability critical loads eventually. The results reveal that under given loading the load factor of dome steel structure is 5.426 and overall instability will not occur.

Abstract: An efficient elastic modulus adjustment procedure to evaluate lower-bound ultimate bearing capacity of spatial frame structures was proposed based on the strain energy equilibrium principle. Four strategies to determine the elastic modulus adjustment factor were developed based on the fixed strain method (FSM), circular arc method (CAM), strain energy conservation law (SECL) and strain energy equilibrium principle (SEEP). The precisions and convergent properties of above four strategies were quantitatively investigated through two numerical examples. The results show that the efficiency and accuracy of the SEEP are of most acceptable.

Abstract: This paper mainly studied the basic principles and methods of the application of fuzzy mathematics to the transaction structure scheme design evaluation of BT(build transfer) mode for university campus construction, also set up multi-level rating index for university campus construction, and decided the weight coefficient and the information collection system. It illustrated the feasibility of this method by empirical study and offered strong theoretical foundation for project decision.

Abstract: Determination of a SDOFS elastic input energy is the primary problem to solve for energy-based design approach. The effect of ground motion and damping ratio were analyzed on the input energy spectra. is selected as the compound ground motion intensity indicator to represent the damage potential of strong ground motion. Through inputting of 188 seismic records according to the site classification of Chinese seismic code, three-segment elastic energy spectra are proposed based on normalization methods. The calculation formula of the peak and the value of long-period section of the input energy spectra are presented for four categories of site conditions by statistical analysis. Moreover, calculation procedure of the total energy input is given in the paper.

Abstract: Featuring for non-linear stress-strain relation, the behavior of thin-wall plates differ widely from stainless steel to carbon steel, which plays a basic role in relevant researches. This paper describes the development of FE models for analyzing stainless steel plates in compression which is based on the existing results of Rasmussen’s test, as well as the strength curve achieved by such advanced FE models. The explicit strength equations and design method are proposed for determining the local buckling strength of stainless plate and cold-formed square and rectangular hollow section in compression. It is shown excellent agreement with test results achieved by using Quach’s model as stress-strain relations in FE models. The proposed design method also exhibits reliable results, which could be used in structural design of stainless steel plates in compression.

Abstract: Abstract. The diamond bird-beak TX-joint is a novel configuration for tubular structures and there are few correlated papers for it. Non-linear FE analysis is carried out on axially loaded TX-joints in order to study the local static behavior of this type of joint. The individual influence of the following geometric parameters on the joint capacity, section width ratio β of brace to chord members, section width to wall thickness ratio 2γ of chord member, and wall thickness ratio τ of brace to chord members is made clear. Increasing either β or τ will enhance the joint capacity and increasing 2γ will lower joint capacity. A reduction equation is proposed to consider the load effect of chord and the axial forces of out-of-plane braces. The tension of out-of-plane braces always lowers the ultimate capacity of joint. The same tension and compression have the equal influence on the joint capacity.