Current Issue : October - December Volume : 2012 Issue Number : 4 Articles : 7 Articles
This paper presents the results of an experimental and computational investigation tailored to examine the response of glass\r\nfiber-reinforced-plastic-(GFRP-) reinforced glue-laminated curved beams and arches. The main objective was to ascertain the\r\nviability of GFRP as an effective reinforcement for enhancing the load carrying capacity and stiffness of such curved structures.\r\nThe study included optimization of the length and thickness of the GFRP reinforcement. In doing so, first a parametric finite\r\nelement study was conducted to evaluate the influence of unidirectional GFRP reinforcement applied onto the arch using eleven\r\npossible configurations and different thicknesses. Subsequently, an experimental investigation was conducted to verify the results\r\nestablished by the finite element method as well as the integrity of actual GFRP-reinforced glue-laminated curved structures. The\r\nresults indicate that GFRP can be considered as an effective and economically viable solution for strengthening and stiffening\r\nglulam arches, without adding any appreciable weight to the structure....
This paper describes the application of a probabilistic structural health monitoring (SHM) method to detect global damage in a\r\nhighway bridge in Connecticut. The proposed method accounts for the variability associated with environmental and operational\r\nconditions. The bridge is a curved three-span steel dual-box girder bridge located in Hartford, Connecticut. The bridge, monitored\r\nsince Fall 2001, experienced a period of settling in the Winter of 2002-2003. While this change was not associated with structural\r\ndamage, it was observed in a permanent rotation of the bridge superstructure. Three damage measures are identified in this\r\nstudy: the value of fundamental natural frequency determined from peak picking of autospectral density functions of the bridge\r\nacceleration measurements; the magnitude of the peak acceleration measured during a truck crossing; the magnitude of the tilt\r\nmeasured at 10-minute intervals. These damage measures, including thermal effects, are shown to be random variables and\r\nassociated P values are calculated to determine if the current probability distributions are the same as the distributions of the\r\nbaseline bridge data from 2001. Historical data measured during the settling of the bridge is used to verify the performance of the\r\nbridge, and the field implementation of the proposed method is described....
The work described in this paper provides an evaluation of an aged pervious concrete pavement in the Northeastern United States\r\nto provide a better understanding of the long-lasting effects of placement techniques as well as the long-term field performance of\r\nporous pavement, specifically in areas susceptible to freezing and thawing.Multiple samples were taken from the existing pavement\r\nand were examined in terms of porosity and unit weight, compressive and splitting tensile strength, and the depth and degree\r\nof clogging. It was concluded that improper placement and curing led to uneven pavement thickness, irregular pore distribution\r\nwithin the pervious concrete, and highly variable strength values across the site, as well as sealed surfaces that prevented infiltration....
Subsurface infiltration and surface bioretention systems composed of engineered and/or native soils are preferred tools for\r\nstormwater management. However, the disturbance of native soils, especially during the process of adding amendments to improve\r\ninfiltration rates and pollutant removal, may result in releases of nutrients in the early life of these systems. This project investigated\r\nthe nutrient release from two soils, one disturbed and one undisturbed. The disturbed soil was collected intact, but had to be airdried,\r\nand the columns repacked when soil shrinkage caused bypassing of water along the walls of the column. The undisturbed\r\nsoil was collected and used intact, with no repacking. The disturbed soil showed elevated releases of nitrogen and phosphorus\r\ncompared to the undisturbed soil for approximately 0.4 and 0.8m of runoff loading, respectively. For the undisturbed soil, the\r\nnitrogen release was delayed, indicating that the soil disturbance accelerated the release of nitrogen into a very short time period.\r\nLeaving the soil undisturbed resulted in lower but still elevated effluent nitrogen concentrations over a longer period of time. For\r\nphosphorus, these results confirm prior research which demonstrated that the soil, if shown to be phosphorus-deficient during\r\nfertility testing, can remove phosphorus from runoff even when disturbed....
Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants of high environmental concern with known carcinogenic\r\nactivity. Although literature documents PAH fate in urban runoff, little is known about their distribution on sediment sizes,\r\nwhich is essential for determining their treatability and fate in receiving waters. This paper has quantified the concentrations\r\nof selected PAHs in urban creek sediments and examined possible relationships between sediment PAH content and sediment\r\ncharacteristics, such as particle size, volatile organic content (VOC), and sediment chemical oxygen demand (SCOD). SCOD,\r\nVOC, and PAH concentrations of sediments showed a bimodal distribution by particle size. The large diameter sediments had\r\nthe highest VOC and also had the highest PAH concentrations. The spatial variation of PAH content by sediment sizes also was\r\nstatistically significant; however, the mass of the PAH material was significantly affected by the relative abundance of the different\r\nparticle size classes in the sediment mixtures....
This study carries out a parametrical analysis of the seismic response to asynchronous earthquake ground motion of a long\r\nmultispan rc bridge, the Fener bridge, located on a high seismicity area in the north-east of Italy. A parametrical analysis has\r\nbeen performed investigating the influence of the seismic input correlation level on the structural response: a series of nonlinear\r\ntime history analyses have been executed, in which the variation of the frequency content in the accelerograms at the pier bases has\r\nbeen described by considering the power spectral density function (PSD) and the coherency function (CF). In order to include the\r\neffects due to the main nonlinear behaviours of the bridge components, a 3D finite element model has been developed, in which\r\nthe pounding of decks at cap-beams, the friction of beams at bearings, and the hysteretic behaviour of piers have been accounted\r\nfor. The sensitivity analysis has shown that the asynchronism of ground motion greatly influences pounding forces and deck-pier\r\ndifferential displacements, and these effects have to be accurately taken into account for the design and the vulnerability assessment\r\nof long multispan simply supported bridges....
This study was conducted to determine some physical and mechanical properties of high-strength flowable mortar reinforced with\r\ndifferent percentages of palm fiber (0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6% as volumetric fractions). The density, compressive\r\nstrength, flexural strength, and toughness index were tested to determine the mechanical properties of this mortar. Test results\r\nillustrate that the inclusion of this fiber reduces the density of mortar. The use of 0.6% of palm fiber increases the compressive\r\nstrength and flexural strength by about 15.1%, and 16%, respectively; besides, the toughness index (I5) of the high-strength\r\nflowable mortar has been significantly enhanced by the use of 1% and more of palm fiber....
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