Advanced Materials Research Vols. 446-449

Abstract: In this paper, the co-rotational total Lagrangian forms of finite element formulations are derived to make elasto-plastic analysis for plane steel frames either under increasing external loading at ambient temperature or under constant external loading at elevated temperatures. Geometric nonlinearity and thermal-expansion effect are taken into account. A series of programs are developed based on the formulations. To verify the accuracy and efficiency of the nonlinear finite element programs, a couple of numerical benchmark tests are carried out. And the results are in a good agreement with solutions from literature. The effects of nonlinear terms of the stiffness matrices on the computational results are investigated in detail. It is demonstrated that the influence of geometric nonlinearity on the incremental step by step finite element analysis for plane steel frames in fire is limited.

Abstract: There are many roads crossed the bridge of the Maglev train. Due to overheight or irregular vehicles may bump or scratch the bridge, damage the electronic lines, or even damage the bridge, it is necessary to monitor these vehicles for the particularity of the Maglev transport. According to the possibility of different injury, this paper developed corresponding recognition modes and methods, discussed several early-warning systems and signal transmission mode. After compared some plans, feasible method was tested. After finished the system design and equipment processing and test, the final testing program was verified using the integrated early-warning system according to the field situation, proved the system reliability, sensitivity. The next step research was suggested.

Abstract: This paper presents the pattern recognition method of structural damage based on least square wavelet kernel function-SVM, which uses limited data about change rate of natural frequency. The method remedies the shortages of traditional methods, which are insensitive to the natural frequency. The result of numerical simulation indicates that the method has favorable recognition precision, better anti-noise capability, and well robustness.

Abstract: Ancient architectures have always been of great interest to a variety of studies. In this analysis, the distribution of ancient architectures in Taizhou, Zhejiang Province is investigated. In each area of the distribution, the characteristic of the ancient architectures are recorded, such as story number, building materials, construction time, etc. The various types of information are then input into a GIS (Geographic Information System) database, which also contains some typical images of the ancient architectures. Some of the data are from GoogleEarth or archived CAD (Computer Aided Design) files. Consequently, the distribution and characteristic of ancient architectures are analyzed consulting the GIS map and attribute table. Although the ancient architectures are similar in Taizhou, Zhejiang Province, there exist some notable differences. The commonness and differences would be significative for the preservation and planning for ancient architectures.

Abstract: Taking the bridge pier monitoring when a municipal engineering was passing through Beijing-Shanghai High Speed Railway (BSHR) as a example, monitoring plan, its implementation of automatic monitoring combined with manual control and comprehensive analysis of monitoring data are introduced ,to provide theoretical reference for similar engineering monitoring plan design .

Abstract: Three types of physical tests were designed to study post failure behaviour and strength attenuation of fine sandstone. Tests include rock compression test, rock unloading test and rock block shear test. The stress-strain curves at different confining pressures had been obtained as well as axial strain-lateral strain curves. The differences of axial strain-lateral strain curves exhibit that stress peak point and the point of fault formation are apparently different for the rock. After the fault is generated, fractured rock slides on the fault surfaces, while confining pressure, material strength and structure effect decide the post failure behaviour. Damaged rock specimens were poured in concrete specimens as well as irregular blocks. Material strength of rock blocks was attained. Shear strength gradually attenuates with unloading points close to the peak. Past the stress peak, rock blocks from fractured rock still have considerable material strength. It is shown that there are differences of strength parameters obtained from direct shear test and triaxial test.

Abstract: The main purpose of this research was to enhance the strength and durability of concrete in both design and construction of high performance concrete. Particularly, the strength in high performance concrete is achieved by optimising the gangue, fly ash and silica fume replacement for cement. The gangue has been used as a cementitious material. Using data from tests on laboratory studies, comparisons are made of the properties and performance of the gangue, fly ash and silica fume concrete with conventional Portland cement concrete of similar and same mixture proportions. The many technical benefits available to high performance concrete user, such as reduced heat evolution, lower permeability and higher strength at later ages, at the same time, in order to increase resistance to sulphate attack and alkali silica reaction. A number of recommendations are given for the effective use of gangue and fly ash in high performance concrete. The results show that 10% gangue, 15% slag, 15% fly ash, 10% silica fume of replacement was found to be an optimum level and demonstrated excellent performance in strength. Literature review on the use of different supplementary cementitious materials in concrete to enhance strength was also reported. The paper is intended to provide guidance for those concerned with the design, application and performance of high properties concrete in practice where gangue and fly ash can also help to reduce costs and energy demands in the production of concrete compared with conventional Portland cement concrete.

Abstract: The extended finite element method (XFEM) is the most effective numerical method to solve discontinuous dynamic problems so far. It makes research within a standard finite element framework and reserves all merits of CFEM. In other side, it needs not mesh repartition to geometric and physical interface. Numerical integration techniques of the XFEM computation are studied, including displacement mode of the XFEM, control equation and infirm solution form of discontinuous medium mechanics problem, region scatteration, element integral strategy.

Abstract: In this paper, a numerical analytical method for singularity problem in V-type notch is presented based on Hamiltonian system. The method has an advantage that all boundary conditions can be considered with one model, and belongs to a general numerical method. Results show that the singularity of the problem relates to the opening angle of the V-type notch where the crack is just a special case. Further, numerical results give rules of stress distribution under various conditions.

Abstract: Theoretic analysis to the stress-strain on the compound board around the hole is made to put forward a feasible method of stress distributing law about the stress concentration. The stress data is obtained from elasticity. Approximate stress concentration factor on the board around the hole is expressed according to the effective data after calculating. A comparison with the theoretical values by ANSYS 10.0 shows that the stress concentration factor is of high precision, so that this method is feasible and accurate.