| With the continuous development of the transportation industry,The probability of ship collisions in reinforced concrete bridge piers across sea and river bridges is greatly increased,however,few studies have reported on the impact of concrete reinforcements with different longitudinal reinforcement ratios.Therefore,it is necessary to further study.This paper uses a double-column circular pier construction bridge as a prototype,different longitudinal reinforcement ratios of the pier model are set by changing the number and diameter of the longitudinal reinforcements of the pier model.Two sets of concrete piers with longitudinal steel bars is ordinary steel bars and longitudinal bars made of stainless steel perform experimental studies and numerical simulations separately.Study on effect of reinforcement ratio on impact effect,dynamic response and concrete damage of two sets of concrete pier specimens.Designed to provide technical support for impact-resistant design and evaluation of reinforced concrete bridge piers,the main content of this article is as follows:1.The theoretical,experimental and numerical simulation studies on the impact of reinforced concrete structures under impact loading are analyzed.Impact test using multi-functional ultra-high drop hammer impact test system perform horizontal impact on the reinforced concrete pier models with different longitudinal reinforcement ratios.The test was carried to comparing the impact force,displacement and strain time history curves of the pier specimens obtained from impact test with ordinary steel reinforcement specimens and stainless steel reinforcement specimens in different impact energy conditions.The impact test results show:the correlation between peak impact force,peak displacement,peak strain and impact velocity is approximately a linear relationship.Under the same impact energy,longitudinal bars are normal steel bars.The reinforcement ratio of longitudinal bars increases from 2.77% to 4.33%.The impact force of the test pieces increases slightly,the average increase amount is 4.7%,and the impact holding time tends to decrease.The average reduction of the tip displacement is about 28.1%,the average reduction of the strain of the No.3 steel bar is about 25.8%,and the average reduction of the No.10 concrete strain is about 37.4%.Under the same impact energy,longitudinal bars are stainless steel bars.The reinforcement ratio of longitudinal reinforcement is increased from 1.25% to 2.21%.The peak of impact force is increased by an average of 34.70%.The average reduction of displacement at the tip of the specimen is approximately 20.13%,the average reduction of the strain of the No.3 steel bar is about 39.63%,the average reduction of the No.10 concrete strain is about 12.7%.The reinforcement ratio increased from 2.21% to 3.46%,the peak impact force increased by an average of 19.44%,the average reduction of the displacement of the top of the specimen was approximately 14.32%,the average reduction of the strain of the No.3 steel bar was approximately 27.40%,the average reduction of strain peak of No.10 concrete is 33.9%.The peak impact force of the stainless steel rebar specimens,the peak displacement,the strain peak with the increase of the reinforcement ratio of the turning point are all near 2.21%.2.Recording and analyze the development of cracks after completion of each impactprocess,and use non-metallic ultrasonic testing Instrument for ultrasonic inspection of pier specimens before and after injury,obtained changes in acoustic parameters of pier specimens before and after injury.By analyzing the crack development of the test piece and the width of the largest main crack,we find that:under the same impact energy,the reinforcement ratio of the longitudinal bars of the specimens with normal steel bars was increased in the range of2.77%-4.33%.The reinforcement ratios of the longitudinal bars of stainless steel bars in the longitudinal bars were in the range of 1.25%-3.46%.It can significantly delay the derivation and development of cracks,reduce the width of cracks,and increase the impact resistance of specimens.Through the analysis of the ultrasonic speed data,the average speed of ultrasonic impact of the impact test piece gradually decreases with the increase of impact energy,it was found that increasing the reinforcement ratio of longitudinal bars of the test piece can effectively analyze the change of the ultrasonic sound velocity of the test piece,under the same impact energy,the reinforcement ratio of longitudinal bars of specimens with normal steel bars was increased from 2.77% to 4.33%.The average reduction of acoustic velocity of specimens was about 14.9%.The reinforcement ratios of specimens with longitudinal bars made of stainless steel were Within the range of 1.25%-3.46%,the average reduction in sound speed is about 20.3%.With the increase of impact energy,the variation laws of the ultrasonic speed and damage factor of the impact specimens are relatively consistent.The average sound velocity of ultrasonic impact specimens decreases with the increase of impact energy,and the damage factor of impact specimen increases with the increase of impact energy.For the two specimens under the impact of the same impact energy,the reinforcement ratio can be increased within a certain range to reduce the damage factor significantly.3.Using finite element simulation software ANSYS/LS-DYNA establish a finite element model for the longitudinal reinforcements with different reinforcement ratios with the specimens of ordinary steel piers and longitudinal reinforcements with stainless steel reinforcement.After analyzing the stress cloud image of the test piece find:the main stress change areas of each model specimen are concentrated at the bottom of impact back and near the impact point.Comparing and analyzing the numerical simulation results and intermediate test results of the two sets of test pieces respectively.The results show:the impact force,displacement and steel strain-time curve model conditions are in line with the impact test conditions. |
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