Advanced Materials Research Vols. 243-249

Abstract: According to the field survey of the damaged engineering structure suffered the flood on July 23rd in Danfeng County, it is analyzed that the failure modes and characteristics of elementary and secondary schools, village and small town residence, roads, bridges and others under the effect of extreme loads, such as debris flow , mountain torrent, landslide and so on. Natural environment must be practically protected in the mountainous area easy to suffer natural calamities. What’s more, good flood carrying capacity of the channels must be assured. Site selection of all different kinds of projects must be serious and careful, and they cannot be located in the ditch mouth of mountain torrents, occupy the flood carrying channels, or be too close to channel bank. Protection works must be set up for the key projects, and the revetment, retaining wall, longitudinal dike, spur dike and others should be fully utilized to resist, eliminate, or weaken extreme loads. It is necessary to strengthen the quality supervision of all diverse kinds of projects in the villages and small towns, perfect the design and construction process, and enhance the anti-scouring capability of the foundation of the projects.

Abstract: The test conditions and main results of wind tunnel test for an exhibition hall and a stadium ribbon-like long span roof of a Sports Convention Center are introduced. We got the average and fluctuating wind pressures of the roof. Then we use typical points measuring method to analyze them. According to the energy contribution method, dominant modes are identified, and the modes response energy is calculated. The coupling coefficient between background displacement response and resonant displacement response is presented in this paper. The stadium calculation mode are Analyzed. The results show that the coupling coefficient numerical range for the ribbon-like long span roof is larger than single-layer spherical shell. When we use energy contribution method to select vibration modes in calculating ribbon-like structure response, Error range is large if the coupling effect is ignored, and some compensatory modes need to be found.

Abstract: In this paper, the structural passive control which has the broad application prospect in seismic shock resistant and the wind-resistant design of civil engineering is introduced. the principle and wide application of structure passive control technology including basal isolation, energy dissipation damping and shock absorption damping in civil engineering are expounded, and the development for passive control technology development is prospected.

Abstract: This paper presents the results of the splitting tensile strength of high fly ash content concrete (HFCC) after high temperature and analysis the degraded rules of the residual splitting strength subjected to high temperature and the replacements of cement by fly ash. The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and were tested after exposure to high temperature 250, 450, 550 and 650°C and room temperature respectively, compared with ordinary Portland cement concrete. The results showed that the splitting tensile strength sensitively decreased with the high temperature increased. Furthermore, the presence of fly ash was effective for improvement of the relative strength. The relative residual splitting strength of fly ash concrete was higher than those of ordinary Portland cement concrete except 30% fly ash replacement. Based on the experiments results, the alternating simulation formula to determine the relationship among relative residual strength, high temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after high temperature.

Abstract: According to the deficiency of present complicate pipe network’s calculating methods in smoke control system, a calculation model of complicate pipe network in buildings smoke control system is established here based on the theory of ventilation network. Graph Theory is used to obtain the model of pipe network in a smoke control system, air leak branch is applied to deal with air leak channels between pressurization area and non-pressurization area in a positive pressure smoke control system, and the equivalent air resistance of air leak branch is also calculated. Based on the equations of nodes flow balance and loop pressure balance, the calculation model of complicate pipe network is built to obtain the distribution method of air flows in a pipe network. The concept of fixed flow branch is introduced here to compute the total pressure drop and airflow regulation parameters of a pipe network. The research work in this paper perfects the calculation methods of complicate pipe network in a building smoke control system.

Abstract: Sewage treatment plant from the pre-treatment unit, biological treatment unit, sludge processing units and related facilities for the earthquake discussed the impact of disasters on the wastewater treatment plant, gives the corresponding contingency measures. Made the transition phase of the wastewater treatment measures in order to provide domestic wastewater treatment plant to develop preventive measures earthquake reference.

Abstract: The sculpture is a special structure. The wind-resistance issue of such a special structure is easily ignored by structural engineers. In this paper, the wind-resistance problem of a real sculpture ‘water-drop’ is investigated by wind tunnel test and theoretical analysis. The results show the original sculpture structure has severe wind-resistance defects. According to these defects, some reinforcing measures for the structure are put forward and put into execution. After the structural modification, the sculpture ‘water-drop’ has been hit by typhoon two times and now stands without any damage. Finally, a workflow is summarized for the wind-resistance appraisal and reinforcement of the existing structures.

Abstract: Shed-tunnel is one of common prevention measures along the highway. Through the wavelet theory we denoised the rockfall impact signal when the rock impact the ordinary shed-tunnel and the energy dissipation shed-tunnel. And then we evaluated the wavelet theory’s denoise effect by the signal-to-noise ratio. The calculation result indicated that the denoise effect is very good. At last, through the autocorrelation analysis and time-frequency analysis for the rockfall impact signal, it was found that the ordinary shed-tunnel’s impact signals didn’t have obvious frequency and the frequency contained many component,but the energy dissipation shed-tunnel’s impact signals had obvious frequency. So the energy dissipation shed-tunnel’s impact signals had a relatively fixed cycle and frequency. The received frequency of rockfall impact by the time-frequency analysis could provide the basis for the design of energy dissipation shed-tunnel’s natural frequency.

Abstract: Theoretical models to calculate the temperature field steel tubes reinforced columns are proposed by finite element program in this paper. The theoretical results are validated by test results, and they have a good agreement. Using the theoretical models, the influencing laws of temperature rising time; section perimeter; steel reinforcement ratio and sectional core area ratio on temperature field are further discussed. It has been found that the surface temperatures of steel tube reinforced columns increase obviously with temperature rising time, and the temperatures of steel tubes and core concrete increase slowly. The effects of sectional dimension and sectional core area ratio on temperature field are significant, but steel ratio has very little effect on temperature both of steel tube and of sectional center. These achievements make it possible to study further theoretical study on the mechanic performance of steel tube reinforced concrete columns in fire.

Abstract: This paper presents field measurement results of boundary layer wind characteristics over typical open country during the passages of typhoon Fung-wong passed by Wenzhou in July 2008. The field data such as wind speed and wind direction were measured from two propeller anemometers placed at the height of about 30m. The measured wind data are analyzed to obtain the information on mean wind speed and direction, turbulence intensity, gust factor, turbulence integral length scale and spectra of wind speed fluctuations. The results clearly demonstrate that the turbulence intensity and gust factor of typhoon Fung-wong are larger than normal, and there is a tendency for the turbulence intensities to decrease with the increase of the mean wind speed, however, there is another tendency for the turbulence integral length scale to increase with the increase of the mean wind speed. The power spectral densities of fluctuating wind speed in longitudinal and lateral directions obtained from the measured wind speed data roughly fit with Von Karman spectra. The results presented in this paper are expected to be of use to researchers and engineers involved in design of low-rise buildings.