نتایج جستجو برای: bridge piers and abutments
تعداد نتایج: 16836952 فیلتر نتایج به سال:
Scour is the erosion of bed and bank material by flowing water; scour poses a threat to bridge security by undermining piers and abutments over time. In fact, “the most common cause of bridge failures is floods with the scouring of bridge foundations being the most common cause of flood damage” (Richardson et al., 1993). While regular inspections and maintenance reduce the risk of a scourrelate...
The use of slot through a pier is a new method proposed to control local scour at bridge piers. In this study, control of local scour at bridge pier is studied using 20 pier models under clear water conditions. The models consist of one circular pier without slot, three round-nosed piers without slot, and 16 piers with slot. Two slot lengths were chosen (yl=b and yl=2b, where y1 is the length o...
Flood currents are considered threatening factors by creating local scour along bridge piers. One method for decreasing local scour is to strengthen the bed against imposed tensions. Among methods which can directly be appropriate in decreasing and controlling local scour of bridge piers is to employ geotextile around bridge piers. In the present study, the effect of geotextile layer in decreas...
introduction: bridges are certainly one of the most important structures but costly service elements in a transport system. the bridges are very required to access the damaged areas in emergency situations such as floods and earthquakes. scour around the foundations of bridge piers exposed to the flowing water than can destroy the bridge itself is a subject of major concern. flow pattern is kno...
The Eads Bridge (St. Louis) and the Brooklyn Bridge (New York City) were testing grounds for caisson construction. These caissons were enormous compressed air boxes used to build riverine piers and abutments anchoring the bridges. Caisson meant faster and cheaper construction, but there was a hidden cost---caisson disease (decompression sickness). Within caissons, workers labored at pressures a...
The seismic assessment of existing bridges is the utmost importance to characterise main structural deficiencies, estimate risk, prioritise retrofit interventions, or losses and repair costs in case earthquakes. above tasks require information on damage mechanisms likely occur as well extent over structure. Such types are generally not provided by classical fragility analysis, which mainly focu...
in this paper the effectiveness combination of bed sill and collar in reduction of local scour depth at cylindrical piers under clear water flow condition was investigated (v/vc=0.9). in the first of experiments, the bed sill was located in downstream and different distances from the piers. results indicated that minimum distance of the bed sill from the piers in downstream has maximum reductio...
One of the most important factors in determining the depth of foundations in structures adjacent to the water flow is the scouring phenomenon; the scouring is a phenomenon caused by the interactions between water flow and erodible bed materials, which causes the removal of sediments where hydraulic structures are located, including bridge piers. Every year, a great number of bridges are damaged...
This paper summarizes results of a major study on jointless bridges sponsored by the U.S. Federal Highway Administration. This study included extensive laboratory and field experiments as well as detailed analytical studies. A set of design recommendations were provided. Jointless bridges have reduced maintenance, improved riding quality, lower impact loads, reduced snowplow damage, and structu...
This paper reports the findings of research examining the blast resistance of bridge piers that are designed in accordance with current knowledge and specifications to ensure ductile seismic performance. Blast testing was conducted on 1/4 scale ductile RC columns, and nonductile RC columns retrofitted with steel jacketing. The seismically designed RC and steel jacketed RC columns did not exhibi...
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