In order to evaluate the seismic reliability of water distribution system and make rehabilitation decisions correspondingly, it is necessary to assess pipelines damage states and conduct functional analysis based on p...
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In order to evaluate the seismic reliability of water distribution system and make rehabilitation decisions correspondingly, it is necessary to assess pipelines damage states and conduct functional analysis based on pipe leakage model. When an earthquake occurred, the water distribution system kept serving with leakage. By adding a virtual node at the centre of the pipeline with leakage, an efficient approach to pressure-driven analysis was developed for simulating a variety of low relative scenarios, and a hydraulic leakage model was also built to perform hydraulic analysis of the water supply network with seismic damage. Then the mean-first-order-second-moment method was used to analyse the seismic serviceability of the water distribution system. According to the assessment analysis, pipes that were destroyed or in heavy leakage were isolated and repaired emergently, which improved the water supply capability of the network and would constitute the basis for enhancing seismic reliability of the system. The proposed approach to seismic reliability and rehabilitation decision analysis on water distribution system is demonstrated effective through a case study.
In order to study the influence of temperature on compressive strength of polymer grouting material,the compression specimen injection mold is self-made,and the uniaxial compressive test was carried out in the tempera...
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In order to study the influence of temperature on compressive strength of polymer grouting material,the compression specimen injection mold is self-made,and the uniaxial compressive test was carried out in the temperature control box under different *** change regularity of compressive strength of polymer grouting material under different temperatures and the law of volume changes of polymer samples were *** experimental results show that：the compressive strength of polymer material increases with the increase of density;the temperature change has a certain influence on the compressive strength of polymer grouting material;the compressive strength decreases with temperature increases under the same density,but the compressive strength is not significantly affected by temperature when the density is less than 0.4 g/cm3;the volume change of the samples accords with the law of thermal expansion and contraction when temperature changes,and the increase of the volume is obvious when it is under high *** achievements will provide an important basis to the application of the polymer grouting material.
Medium-scale dynamic triaxial tests were carried out to investigate the residual deformation behavior of Municipal Solid Waste (MSW) in different degree of biodegradation. Based on modified Shen Zhujiang models which ...
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Medium-scale dynamic triaxial tests were carried out to investigate the residual deformation behavior of Municipal Solid Waste (MSW) in different degree of biodegradation. Based on modified Shen Zhujiang models which are respectively related with stress level and consolidation stress ratio, parameters for modeling MSW residual deformation were derived for different degree of biodegradation. The research indicated: the residual deformation behavior can be simulated with modified Shen Zhujiang model in 0% and 50% degree of biodegradation. The parameters fitting is acceptable when the stress level index is 0.5 or the consolidation ratio index is 0.8. The MSW residual deformation parameters gradually reduce as degree of biodegradation increases under the different failure criterion. The results in this paper can be used as reference for seismic design and estimation of permanent displacement of landfill.
The mechanical behaviors of polypropylene fiber reinforced red clay are studied by means of different test methods. The compaction test and the permeability test show that the maximum dry unit weight of the fiber rein...
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The mechanical behaviors of polypropylene fiber reinforced red clay are studied by means of different test methods. The compaction test and the permeability test show that the maximum dry unit weight of the fiber reinforced red clay is basically a constant value and the variation range of the optimum moisture content is great with certain fiber content. It has the same magnitude of permeability coefficients as the fiber reinforced red clay and the permeability coefficient is small. The results of direct shear test, unconfined compressive test and triaxial consolidation undrained test show the strength of the fiber reinforced red clay is obvious higher than that of the red clay, which increases with the fiber content and length. After being mixed with fiber, the cohesion of red clay rises a lot and the change of friction angle is small. The stress-strain curve of the fiber reinforced red clay shows typical work hardening character. The sample has the character of bulging breakage.
The decision-making on capital structure is a core issue of modern corporate financing management, whether the decision result is correct or not directly affects the effect of capital operation and the economic benefi...
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There are a variety of uncertainties in construction projects because of the uniqueness, complexity and the one time off characteristics of each project. Especially in the investment decision-making stage, decision-ma...
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Extensively researches have been carried out on seismic analysis of space structures subjected to multi-dimensional multi-support excitations. However, the research on dynamic reliability of stochastic response is jus...
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Extensively researches have been carried out on seismic analysis of space structures subjected to multi-dimensional multi-support excitations. However, the research on dynamic reliability of stochastic response is just little. Extreme value distribution (EVD) of dynamic response of stochastic space structures is so necessary to dynamic reliability. Nevertheless, there is no effective approach to obtain EVD as yet. Hence the recently formulated probability density evolution method (PDEM) is adopted to obtain the EVD and subsequently evaluate dynamic reliability of space structure subjected to multi-dimensional multi-support excitations. PDEM can effectively gain the EVD and calculate the dynamic reliability of stochastic structures. To demonstrate the accuracy and efficiency of the PDEM in space structures, a single-layer spherical reticulated dome is extensively researched and the EVD and dynamic reliability is observed and analyzed, respectively. In the present paper five apparent wave velocities and four displacement thresholds in vertical direction are taken into consideration. Compared with the results evaluated by conventional simulation method, the PDEM is of accuracy, efficiency and versatility in space structures.
Parametric sensitivity is important for reliability design, optimization and evaluation. The parametric sensitivity and reliability of two typical spatial structures, a star-shaped dome and a lattice truss, are invest...
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Parametric sensitivity is important for reliability design, optimization and evaluation. The parametric sensitivity and reliability of two typical spatial structures, a star-shaped dome and a lattice truss, are investigated. Four parametric importance measures are employed to identify the relative importance of each random variable under deformation capacity limit state, and the sensitivities of their means and standard deviations on the reliability index are researched. The FOSM (first-order second moment) and the FORM (first-order reliability method) are employed to carry out the sensitivity analysis. The main conclusions are as follows: the influence of the randomness of nodal coordinates on the reliability and sensitivity of these two spatial structures cannot be neglected as it can play an important role;the variables reduction technique (VRT) is an effective way to reduce the considerable computational efforts of reliability analysis for large-scale space structures;the reliabilities of these two structures will decrease with the increase in correlation between the variables.
According to the damage mechanism of concrete material during the uniaxial compressive failure process,this paper further establishes the statistical damage constitutive model of concrete subjected to uniaxial compres...
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According to the damage mechanism of concrete material during the uniaxial compressive failure process,this paper further establishes the statistical damage constitutive model of concrete subjected to uniaxial compressive stress based on the statistical damage model under uniaxial tension. The damage evolution law in the direction subjected to pressure is confirmed by the tensile damage evolution process of lateral deformation due to the Poisson effect,and then the compressive stress-strain relationship is defined. The peak nominal stress state and the critical state occurring in the macro longitudinal distributed splitting cracks are distinguished. The whole loading process can be divided into the even damage phase and the local breakage phase. The concrete specimen is divided into the failure process zone and the resting unloading zone. The size effects during the local breakage phase under the uniaxial monotonic compressive process and the hysteretic phenomenon under the cyclic compressive loading process are analyzed. Finally,the comparison between theoretical results and experimental results preliminarily verifies the rationality and feasibility of understanding the failure mechanism of concrete through the statistical damage constitutional law.
Floors are almost always designed against the action of static loads, despite everyday evidence that dynamic loads are also of great importance and therefore there is a growing need for measurement of dynamic paramete...
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ISBN:
(纸本)9781622761753
Floors are almost always designed against the action of static loads, despite everyday evidence that dynamic loads are also of great importance and therefore there is a growing need for measurement of dynamic parameters like natural frequencies, and damping ratio of the floors. Timber-concrete composite (TCC) floors have been found to resolve vibration susceptibility and low impact insulation issues concerned with full timber floors;however, the composite behaviour of TCC floors depends primarily upon the efficiency of the connection system used. The dynamic parameters of the flooring system can be used to assess the efficiency of the connection system. This paper presents a comprehensive review on dynamic parameters of TCC flooring systems and tests to determine these parameters. Serviceability requirements for TCC floors to control vibration are also discussed. Brief description of ongoing dynamic tests using instrumented hammer test on TCC beams are finally presented.
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