Advanced Materials Research Vols. 919-921

Abstract: A new method is proposed to identify structural damages based on the power spectral density sensitivity analysis. The responses of the structure under stationary and random excitations are obtained using pseudo excitation method, and then the sensitivities of power spectral density with respect to the structural damage parameters are obtained similarly. Finite element model updating method is adopted to identify the structural damages. A numerical example of a shearing structure demonstrates the satisfactory results obtained from the present method.

Abstract: Due to the fatigue load and bad corrosion environment, truss structure in service will form the damage accumulation, damage detection of potentially damaged elements of truss structures is a challenging topic. According to the element stress characteristics of truss structure, structural element strain mode mainly based on the vibration displacement is derived, the change of elemental strain modal is proposed as the dynamic indicator for damage location identification of truss structure. Based on the numerical simulation study of the actual truss structure indicates that, the loworder elemental strain modal method is not only sensitive to damage identification of chord element and web element of truss structure, but also is effective to locate the damage of different position, and is suitable for damage alarming of truss structure in service.

Abstract: Construction of denitrification system is an important environmental engineering in power industry now. Denitrification system is always set over the blower bracket, frame for denitrification needs to pass through existing structure if blower bracket works together with boiler frame. Based on the denitrification project of a power plant in north China, this paper puts forward reasonable structural arrangement of steel frame through existing structure, which is that frame for denitrification works alone and the column affected by existing structure selects solid-web column with openings. The beam supporting SCR reactor could be simplified as a beam under dead load only. Optimal design of its section in simplified model can improve design efficiency and economize the cost. The critical load of special column with bracings can be obtained by the linear elastic buckling analysis and effective-length factor can be calculated according to Euler Formula.

Abstract: Taking structure strengthen of a large hotel as the engineering background, based on superposition principle, put forward the design method of concrete two-way slab strengthened with partially bonded steel plate. According to the finite element analysis, the solid finite element model is established, and then the stress, strain and deflection of two-way slab strengthened with bonded steel plate is obtained, at the meantime compared with the load test datum in situ. The analysis results show that the finite element software is a reliable tool applied to analyze the design of two-way slab strengthened with bonded steel plate. When the increasing load is larger, partially bonding steel plate strengthening has more advantage and economize than bonding carbon fiber strengthening on two-way slab, meanwhile that slab strengthened with partially bonded steel plate has better mechanical properties, strength and stiffness.

Abstract: We analyzed the rectangular slab with four sides supported, respectively elastic and plastic methods of calculation the slab. Generally considered l₂/l₁≤2 calculated as the two-way slab, 2< l₂/l₁<3 should be calculated as the two -way slab, however l₂/l₁≥3 calculated as one-way slab, consider these provisions is not reasonable, analysis shows, if using elastic or plasticity theory analysis, l₂/l₁ <3, or l₂/l₁ <4 as the two-way slab. Otherwise, it is one-way slab. Reasonable distinction between one-way slab and two-way slab are meaningful, not only simplifies the calculation, but also makes the design economical, safe and reliable.

Abstract: With the background of optimal design study on main powerhouse of Power Plant, the finite element software ANSYS is adopted to control the overall structure's displacement. After the choice of structural form and loads bearing system, the static and dynamic characteristics of this boiler steel frame are analyzed in detail. And the structure's displacement response of this boiler steel frame will also be discussed under permanent load, wind load and seismic action. The structural displacement response causing by four wind load cases (front wind, back wind, left wind and right wind) is emphatically discussed and the dynamic characteristics and response spectrum analysis are also be studied. Results show that this main powerhouse owns good seismic performance and excellent lateral displacement resistance capacity because of the high structure stiffness. It shows that the horizontal displacement of the whole structure under all load cases can meet the requirements of the limit value, which demonstrates the feasibility of this structural program.

Abstract: Modal solutions of plates with uniformly varying cross section using unified beam theory are presented. The results are given in the form of Euler-Bernoulli, Timoshenko and quasi 3D solutions. Numerical results for cantilever and CFCF supported rectangular planform plates are presented. Different types of modes, i.e. axial, bending and torsional modes are observed. The frequency values are in good agreement with 3D finite element results as well as published literature. Due to uniform taper in plate cross section, bending vibration modes become asymmetric along the longitudinal axis of the structure. Further, it can also be noticed that the vibration behavior of thick tapered plates is characterized by the appearance of significant number of axial and torsional modes at lower frequency values.

Abstract: This paper reports on part of an ongoing experimental program at the University of Adelaide on FRP-concrete-steel double-skin tubular columns (DSTCs). The main emphasis of the study reported in this paper was to investigate the influence of loading pattern on the axial compressive behavior of DSTCs. To this end, 12 hollow and concrete-filled DSTCs were manufactured and tested under monotonic or cyclic axial compression. All of the specimens were manufactured using high-strength concrete (HSC). The results of the experimental study indicate that that concrete in cyclically loaded hollow DSTCs exhibits slightly larger strength and strain enhancement ratios than concrete in companion monotonically loaded DSTCs. The results also indicate that concrete in filled DSTCs exhibit slightly larger strength enhancement ratios than and similar strain enhancement ratios to concrete in monotonically loaded DSTCs.

Abstract: A damage occurrence of single-span type greenhouse by heavy snowfall in Korea, M shape collapse where excessive snow load of the roof occurs frequently regardless of the area damaging all the roof rafters. Therefore, in this paper, the snowdrift pattern of the arched house by shape using snow wind tunnel simulation is necessary. Experimental results indicated that the snowfalls on the roof of the arched house occur variously depending on the shape and location. As a result of estimating the load standard by roof slope angle and the values of snow loads using wind tunnel experiment, roof slopes showed 30% in 0°-15°and 80% in 45°-70° respectively, which were significant percentages in the snowdrift experiment.

Abstract: High-rise building is one of solution for lack of houses and offices in downtown. And high-rise buildings can be built by application of high strength materials such as structural steels and concrete. Particularly, high strength structural steels have much efficient properties in not only design phase but construction one. Therefore, the use of the high strength structural steels has been increased every year. However, the H-section made of the high strength structural steels can be designed and constructed with longer height than that was evaluated for fire resistance by fire test to satisfy the fire regulation. In this study, to suggest an exact fire performance at high temperature of H-section made of high strength structural steels, a fire engineering technique was used. The derived facts showed that SM 570 revealed better structural stability at high temperature and as longer length of H-section was used, the more fire protection materials requited.