Applied Mechanics and Materials Vols. 438-439

Abstract: This paper uses the large-scale finite element analysis software ABAQUS to simulate 12 cross steel reinforced concrete special-shaped columns with the control variables of axial compression ratio and rate of steel bone, and subjected to the monotonic load with 20mm horizontal displacement. 6 columns work under the different axial compression ratio of 0.0, 0.4, 0.5, 0.6, 0.7 and 0.8. Other 6 columns are made of different rates of steel bone with different steel bone thickness of 0mm, 2mm, 4mm and 6mm, 8mm and 10mm, and subject to vertical axial force in axial compression ratio of 0.3. By simulating, we obtain the load - displacement curve of different axial compression ratios and different rates of steel bone, and analyze the effect of the bearing capacity of the cross steel reinforced concrete special-shaped columns in different parameters. The results show that the bearing capacities of the columns decrease with the increasing ratio of axial compression, and increase with the increasing rate of steel bone.

Abstract: After fire, the strength of steel materials and stiffness of artifacts decrease significantly, which cause the redistribution of internal forces and increase the difficulty in testing of materials, identification and evaluation of steel structures after fire. This paper mainly discusses the identification and evaluation of steel structure of one project undertaken a fire by empirical test. It is speculated that the temperature of the fire was more than 850°C, area covered includes 1~4/Q~W axis and 5~6/H~W axis of the factory, after the fire in the safety appraisal building assessment, it is categorized as class C which influences the safety of the whole structure. From the results of this appraisal, suggestions are made which could be regarded as a guide in similar engineering projects in the future.

Abstract: Over decades phased array antenna technique attracts much more attention in Lamb wave based structural damage detection. Lamb wave generated by the piezoelectric wafers omnidirectionally could be steered at a specific direction during its propagation. Thus, the wave beam steering and focusing has been established, the location of structural damage is done with pulse-echo method by wave propagation. However, the detection accuracy will decrease as side bands energy leakage during wave propagation, so, signals to be generated have to be modified by window tone burst in order to concentrate energy in main bands and minimize the effect of dispersion side bands. In this paper, signals modified by Hanning-windowed tone burst was used to decrease the effect of side bands energy leakage, the results improved the detection accuracy better than signals without window tone burst and show good agreement with theoretical results. Meanwhile, a numerical simulation of aluminium plate demonstrates that phased array antenna technique is feasible in structural damage detection.

Abstract: The relative discussion and research of Micro-Electro-Mechanical System (MEMS) and pressure sensor is carried out in this paper. The working principle of pressure sensor is analyzed, and the cantilever piezoresistive pressure sensor is studied in details. The electricity design of pressure sensor is researched. The open loop Wheatstone-bridge design is adopted in this paper, which adds the freedom of disposing circuit.

Abstract: Combined with erection of an archaized steel tower in Luoyang, China, stresses in key members, displacements of control nodes and temperature variation of steel skeleton were monitored and analyzed. The temperature range for erecting structure is optimized based on finite element simulation analysis with 5°C, 10°C, 15°C and 20°C as closure temperature. It is confirmed by actual test values of steel tower. And the recommended temperature range is given between 15°C and 20°C. In case of dead weight + live load + temperature, test values are consistent with theory values. Maximum tensile stress and compressive stress are 64.0MPa and-61.0MPa respectively. The structure is safe during whole process of erection. The result obtained in the paper would have some references for the design and construction of similar steel structures.

Abstract: Combined with a 2×350MW gas power station project, the main construction process and specific technology of each subentry project for a large hyperbolic cooling tower were described in details. The customized steel templates were used and positioned by accurate calculation. The mass concrete was poured by alternative bay construction which replaced deformation joint and after-pouring belt. The measures such as controlling temperature, avoiding leakage and monitoring geometric size were taken actively. These methods greatly improve the quality of the structure and are strong guarantee for achieving high-quality project.

Abstract: Concrete lining structure was adopted as channel lining structure of South-North Water Transfer Project, China. The structure is made up of concrete, composite geomembrane, sand bed and insulation board. However, the faces displacement of concrete lining emerged at test section on some canal of the project. The experiment researches the friction coefficient between the weak level performance of the system, which provides the base for designing and construction.

Abstract: DJIPLOHO conducts the first drainage vent test of diversion tunnel after completing in the construction of hydropower station with a water commissioning. Through the data analysis and research for the testing process, it is necessary and has flexibility to adjust accurately the drainage. Test results verify the rational design and safety of the tunnel and prove the correctness of first drainage tests procedures. It also accumulates valuable experience for the same type of drainage project for the first time.

Abstract: In order to optimize the stiffener penstock structure in hydropower stations, the simple genetic algorithm and the direct search method in traditional optimization methods were integrated, and a new hybrid genetic algorithm was obtained. A mathematical model of the stiffener penstock structure was established, and the constraint expressions were presented for global stability of the penstock under external pressure as well as the local stability of the stiffening ring. The corresponding program was developed and applied to a hydropower station. Results show that compared with the original design, the optimized design of rectangular stiffener rings reduces the penstock wall thickness by 8%, saving steel products 12.9%. The economic benefit of optimization is very considerable.

Abstract: In recent years, hydropower as one kind of the most economical and environmental energy got the swift and violent development, it is important to ensure the safety of hydropower station. Combined with practical engineering of Dandong hydropower station, the simulation model of hydropower station is built by three-dimensional finite element software, the bifurcated pipe is analyzed under the static and dynamic loads which are caused by reconstruction of Yueshan railway station. The results show that the stresses and displacements increment are smaller under the loads, the natural frequency of vibration and the frequency of railway bridge are different largely, which does not produce resonance. Therefore, the hydropower meets the safety requirements under different railway bridge loads.