Showing papers in "alexandria engineering journal in 2010"
TL;DR: In this paper, the effect of geosynthetic reinforcement on the cumulative settlement of repeatedly loaded rectangular model footings placed on reinforced sand was studied and the ultimate bearing load and cumulative settlement were obtained and analyzed.
Abstract: The paper presents a laboratory study of the effect of geosynthetic reinforcement on the cumulative settlement of repeatedly loaded rectangular model footings placed on reinforced sand. Repeated load tests were carried out with different initial monotonic load levels to simulate structures in which live loads change slowly and repeatedly such as petroleum tanks and ship repair tracks. Three series of tests were carried out. Tests of series 1 were performed to determine the ultimate monotonic bearing capacity. Tests of series 2 were performed on unreinforced sand under vertical repeated loads. Tests of series 3 were performed to study the effect of sand reinforcement on the footing response under the same loads. The studied parameters include the initial monotonic load levels, the number of load cycles, and the relative density of sand along with geosynthetic parameters including size and number of layers. Both the ultimate bearing load and the cumulative settlement were obtained and analyzed.
51 citations
TL;DR: In this paper, the authors present the results of laboratory model tests for studying the improvement of soft clay layer by using both partially replaced sand piles with and without confinement by skirts, which can substantially modify the stress displacement curve of the footing, significantly decreases the settlement and the replaced soil block inside the skirts behave as deep foundation.
Abstract: This paper presents the results of laboratory model tests for studying the improvement of soft clay layer by using both partially replaced sand piles with/without confinement. This research is performed to study the effect of sand pile to improve the bearing capacity and to control the settlement. Also the research aimed at investigating the variation of subgrade modulus, and the induced failure mechanism of shallow circular footing on replaced soil with/without skirts. The results show that the improvement of load bearing capacity is remarkable; using both partially replaced sand pile with and without confinement by skirts. The adopted technique can substantially modify the stress displacement curve of the footing rested on soft clay layer, significantly decreases the settlement and the replaced soil block inside the skirts behave as deep foundation. Therefore, the bearing capacity failure mechanism of a footing rested on soft clay can be modified from exclusive settlement to general bearing capacity failure at the tip of confined replaced sand column.
33 citations
TL;DR: In this article, the performance of skirted footings subjected to lateral forces was studied. And the effects of skirt length and the relative density of sand on the performance were investigated through laboratory testing program, and a comparative experimental study between ultimate horizontal loads attained by skirted and unskirted feetings with the same properties was conducted.
Abstract: Shallow footings are subjected to lateral forces induced by earthquake movements, wind loads, water wave pressure, lateral earth pressure, and transmitting power cables. In some structures such as water front structure, earth retaining structure and transmitting power structures, the lateral forces acting on the footings may be dominant. There has been little work studying the performance of skirted footings subjected to lateral loads. Twelve loading tests were performed on small scale circular skirted footing to shed some light on the performance of skirted footings when subjected to lateral loads. The effects of skirt length and the relative density of sand on the performance of the footing were investigated through laboratory testing program. Also a comparative experimental study between ultimate horizontal loads attained by skirted and unskirted footings with the same properties was conducted. From the accomplished laboratory tests it was found that the skirts changed the failure mode of circular shallow footings from sliding mechanism into rotational mechanism. Also the skirts attached to footings increased appreciably the ultimate horizontal capacity of shallow footings.
28 citations
TL;DR: In this article, the effect of different shapes of stilling basins of regulator on the length of the submerged hydraulic jump, velocity profiles along the apron, and local scour downstream regulator floor was investigated.
Abstract: Barrage regulators are considered as one of the most important projects in the Egyptian irrigation practice, which is obvious by its controlling of the released discharge and both of upstream and downstream water levels. In the present time, the ministry of water resources and irrigation starts to construct new barrages on the River Nile instead of the oldest ones, which are not able to withstand the requirements of increasing head difference between the upstream and downstream water levels upon the gates. The present study was focused on investigating the effect of different shapes of stilling basins of regulator on the length of the submerged hydraulic jump, velocity profiles along the apron, and local scour downstream regulator floor. Extensive experimental program was conducted on a re-circulating flume with 1.0 m wide, 26.0 m long and 1.2 m deep, with discharges range from 40 to 190 l/s. The relative velocity near bed, and shear Reynolds number were studied to fix the best shape of stilling basin that could reduce both of length of submerged hydraulic jump and local scour downstream stilling basin. Statistical equation was developed to correlate the length of submerged jump with the other independent parameters. Finally, clear matching of results from the length of jump and velocity analysis was investigated.
15 citations
TL;DR: In this article, a higher order finite element model based upon Mindlin plate theory was employed to analyze different shapes of glass plates, and a comparison between experimental and finite element results for a tested trapezoidal glass plate was presented.
Abstract: Architectural designers frequently use glass plates that have shapes other than rectangular in both residential and commercial buildings. Commonly, one sees glass plates with trapezoidal, triangular, hexagonal, and circular shapes. For example; window glass in aircraft control tower cabs leans outward to enable ground controllers to have a good view of operations. Consequently, aircraft control tower cabs have glass plates that have trapezoidal shapes. This paper deals with the structural behavior of glass plates other than rectangular shapes. A higher order finite element model based upon Mindlin plate theory was employed to analyze different shapes of glass plates. First, a comparison between experimental and finite element results for a tested trapezoidal glass plate is presented, which shows a very good agreement. Then, the finite element model was used to compare load-induced stresses with those for bounding rectangular shapes. Results of analysis are presented and discussed.
4 citations
TL;DR: In this article, the effects of bulging width, length, and shape on the pile ultimate load were investigated and it was found that bulging can increase the ultimate load up to 200%.
Abstract: Piled foundation is a method of overcoming difficulties of founding on soft soils to ensure structural safety by transferring structural load through weak soil to a stiff stratum Due to piles importance, it is becoming necessary to avoid pile defects These defects arouse from inadequate ground investigations, construction phases, pile loading test, and natural unforeseen geological causes In this paper bulging is studied as a pile imperfection The effects of bulging width, length, and shape on the pile ultimate load are investigated Bulging may increase pile ultimate load though it is still considered as a pile defect It was found that bulging can increase the ultimate pile load up to 200%
3 citations
TL;DR: In this article, the authors focus on the modeling of stub-girders with full and partial shear connection in two and three dimensions, where the shear connectors are modeled as springs to consider the geometry of studs in addition to the nonlinearity due to the interaction between the Shear connector and the concrete slab.
Abstract: A stub-girder floor system is a composite system constructed from a continuous steel beam and a reinforced concrete slab separated by a series of short, typically wide, flange sections called stubs. The finite element method has been used in the analysis of this composite system where it is capable to represent the constituent parts, adopt adequate elements and use appropriate solution techniques. As the behavior of stub-girders presents significant nonlinear effects, it is fundamental that the interaction of all different components should be properly modeled as well as the interface behavior. The present work focuses on the modeling of stub-girders with full and partial shear connection in two and three dimensions. The proposed model contains all the main structural parameters and their associated nonlinearities (concrete slab, steel beam, stubs, and shear connectors). In this model, the shear connectors are modeled as springs to consider the geometry of studs in addition to the nonlinearity due to the interaction between the shear connector and the concrete slab. Tests and numerical results available in the literature are used to validate the models. Based on the proposed finite element model, an extensive parametric study of stub-girders is performed, considering the material properties, relative dimensions and shear connector characteristics, where valuable recommendations and conclusions are achieved.
3 citations