Current Issue : July - September Volume : 2019 Issue Number : 3 Articles : 5 Articles
Inflow and infiltration (I&I) is an unavoidable problem which affects underground infrastructures such as water mains, sewer\nlines, and storm water systems. The additional water and intruded debris, due to I&I, can hinder the flow capacity of the pipe\nnetwork. However, with proper management, such problems can be minimized or controlled. By using a qualitative approach to\ndetermine the areas susceptible to I&I, application of geographic information system (GIS) can minimize cost and time. The\nresults found can highlight the most I&I vulnerable areas, which can be used for underground infrastructure management. In this\nstudy, maps of Youngstownâ??s sewer lines and surrounding areas were generated and used. Pipe age, an empirical operating\ncoefficient, sewer classifications, and soil hydraulics were the parameters used to identify each pipe segments. The results of this\nstudy show that majority of pipelines from downtown and south side of the city were determined to be in very poor conditions.\nThe method used in this study reduces the scale of work, by generating a map, indicating areas with highest susceptibility....
The analysis of the ductility and cumulative plastic deformation (CPD) demand of a high-performance buckling-restrained brace\n(HPBRB) under a strong earthquake and its aftershocks is conducted in this paper. A combination of three continuous excitations\nwith the same ground motion is used to simulate the affection of a strong earthquake and its aftershocks. A six-story HPBRB frame\n(HPBRBF) is taken as an example to conduct the incremental dynamic analysis (IDA). The seismic responses of the HPBRBF\nunder one, two, and three constant continuous ground motions are compared. TheIDA result indicates that the ductility and CPD\ndemand of the BRBs under the three constant continuous ground motions are significantly larger than that excited by only one.\nProbabilistic seismic demand analysis (PSDA) is performed using seven near-fault ground motions and seven far-fault ground\nmotions to consider the indeterminacy of ground motion. The probabilistic seismic demand curves (PSDCs) for the ductility and\nCPD demand for the HPBRB under the strong earthquake and its aftershocks are obtained in combining the probabilistic seismic\nhazard analysis. The results indicate that the AISC threshold value of the CPD with 200 is excessively low for a HPBRBF which\nsuffers the continuous strong aftershocks with near-fault excitations, and a stricter threshold value should be suggested to ensure\nthe ductility and plastic deformation capacity demand of the HPBRB....
In this study, a series of shaking table tests were conducted using a specimen that consisted of a superstructure, incorporating a\nfriction device and a sway-rocking mechanism under the superstructure to determine the optimal damper slip force of a passive\nvibration control system considering the effects of sway-rocking motion. The adopted simple friction device, composed of rubber\nbands and stainless steel plates, allowed the magnitude of the slip force to be easily set. The optimal slip force of the friction device,\nwhich minimizes the peak and root-mean-square response of the superstructure subjected to earthquakes, was determined from\nthe shaking table tests. Based on the results, the optimal slip force of the friction device was found to vary according to the input\nlevel of the ground motions and the sway-rocking conditions. The obtained results suggest that the effect of sway-rocking motion\nshould be considered in the design of passive control structures and the determination of their optimal damper slip force....
Loess is a kind of special soil with structure and hydrocollapse behavior; due to the particularity of loess, the deformation\nregularity of the tunnel in loess shows different characteristics from those in rock. To ensure the safety of construction, crown\nsettlement (CS) and horizontal convergence (HC) are widely used to assess the stability of the tunnel structural system. Based on\nstatistical analysis, this study focused on analyzing the influence of cover depth on the deformation of surrounding rock of loess\ntunnels by ANOVA, and relationships between them were presented by regression analysis. The achieved results indicated that the\ninfluence of cover depth on deformation was not obvious in shallow tunnels, while the cover depth had a significant effect on\ndeformation in deep tunnels. Based on the difference of influence of cover depth on deformation between shallow tunnels and\ndeep tunnels, a method for determining the cover depth threshold (CDT) in the tunnel by statistical analysis was proposed. The\nhorizontal and vertical deformations in shallow tunnels were discrete and obeyed the positive distribution, mainly concentrated\nwithin 200 mm. The deformation allowance in shallow tunnels was recommended to be 200 mm. In deep tunnels, as the cover\ndepth increased, the deformation increased linearly, while the CS/HC decreased....
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