Use of UHPFRC(ultra high performance fiber reinforced concrete)cast-in-situ over-lays for repairs and strengthening of bridge decks is already quite a widely used technology,while use of this method for strengthening ...Use of UHPFRC(ultra high performance fiber reinforced concrete)cast-in-situ over-lays for repairs and strengthening of bridge decks is already quite a widely used technology,while use of this method for strengthening of bridge supports is still much less often.This paper describes the first use of this technology for bridge abutments in the Czech Republic,and if we know well,also the first use of such a ribbed over-lay internationally.展开更多
Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was...Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.展开更多
Local scour around bridge piers and abutments is one of the most significant causes of bridge failure.Despite a plethora of studies on scour around individual bridge piers or abutments,few studies have focused on the ...Local scour around bridge piers and abutments is one of the most significant causes of bridge failure.Despite a plethora of studies on scour around individual bridge piers or abutments,few studies have focused on the joint impact of a pier and an abutment in proximity to one another on scour.This study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water scour.The experiments were conducted in a rectangular laboratory flume.They included 18 main tests(with a combination of different types of piers and abutments)and five control tests(with individual piers or abutments).Three pier types(a rectangular pier with a rounded edge,a group of three cylindrical piers,and a single cylindrical pier)and two abutment types(a wingewall abutment and a semicircular abutment)were used.An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline,velocity magnitude,vertical velocity,and bed shear stress.The results showed that the velocity near the pier and abutment increased by up to 80%.The maximum scour depth around the abutment increased by up to 19%.In contrast,the maximum scour depth around the pier increased significantly by up to l71%.The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87%relative to the case with a solitary abutment.Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment.展开更多
The rotation of skew bridges in the plane is a common phenomenon in engineering. Traditional measure is to setup pins or limiting displacement with lateral bearings, but the result is not satisfactory. In order to sol...The rotation of skew bridges in the plane is a common phenomenon in engineering. Traditional measure is to setup pins or limiting displacement with lateral bearings, but the result is not satisfactory. In order to solve this problem, the reason for the rotation in the plane is found by philosophy analysis and an idea regarding the application of slantleg frame skew bridges without abutment is brought forward in this paper. Theory and engineering practices indicate that slant-leg rigid frame bridges without abutment can restrain the rotation of skew bridges in the plane to the utmost extent because of its structural characteristics and can fundamentally solve the tough defect of skew bridges.展开更多
基金For reconstruction of the bridge,results of research projects FV20472(TRIO)SGS20/108/OHK1/2T/11(CTU in Prague)were partly used.
文摘Use of UHPFRC(ultra high performance fiber reinforced concrete)cast-in-situ over-lays for repairs and strengthening of bridge decks is already quite a widely used technology,while use of this method for strengthening of bridge supports is still much less often.This paper describes the first use of this technology for bridge abutments in the Czech Republic,and if we know well,also the first use of such a ribbed over-lay internationally.
基金Project(51378503)supported by the National Natural Science Foundation of ChinaProject(2010G018-A-3)supported by Technology Research and Development Program of the Ministry of Railways,China
文摘Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.
文摘Local scour around bridge piers and abutments is one of the most significant causes of bridge failure.Despite a plethora of studies on scour around individual bridge piers or abutments,few studies have focused on the joint impact of a pier and an abutment in proximity to one another on scour.This study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water scour.The experiments were conducted in a rectangular laboratory flume.They included 18 main tests(with a combination of different types of piers and abutments)and five control tests(with individual piers or abutments).Three pier types(a rectangular pier with a rounded edge,a group of three cylindrical piers,and a single cylindrical pier)and two abutment types(a wingewall abutment and a semicircular abutment)were used.An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline,velocity magnitude,vertical velocity,and bed shear stress.The results showed that the velocity near the pier and abutment increased by up to 80%.The maximum scour depth around the abutment increased by up to 19%.In contrast,the maximum scour depth around the pier increased significantly by up to l71%.The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87%relative to the case with a solitary abutment.Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment.
文摘The rotation of skew bridges in the plane is a common phenomenon in engineering. Traditional measure is to setup pins or limiting displacement with lateral bearings, but the result is not satisfactory. In order to solve this problem, the reason for the rotation in the plane is found by philosophy analysis and an idea regarding the application of slantleg frame skew bridges without abutment is brought forward in this paper. Theory and engineering practices indicate that slant-leg rigid frame bridges without abutment can restrain the rotation of skew bridges in the plane to the utmost extent because of its structural characteristics and can fundamentally solve the tough defect of skew bridges.
