With the change of the main influencing factors such as structural configuration and impact conditions,reinforced concrete slabs exhibit different mechanical behaviors with different failure patterns,and the failure m...With the change of the main influencing factors such as structural configuration and impact conditions,reinforced concrete slabs exhibit different mechanical behaviors with different failure patterns,and the failure modes are transformed.In order to reveal the failure mode and transformation rule of reinforced concrete slabs under impact loads,a dynamic impact response test was carried out using a drop hammer test device.The dynamic data pertaining to the impact force,support reaction force,structural displacement,and reinforcement strain were obtained through the use of digital image correlation technology(DIC),impact force measurement,and strain measurement.The analysis of the ultimate damage state of the reinforced concrete slab identified four distinct types of impact failure modes:local failure by stamping,overall failure by stamping,local-overall coupling failure,and local failure by punching.Additionally,the influence laws of hammerhead shape,hammer height,and reinforcement ratio on the dynamic response and failure mode transformation of the slab were revealed.The results indicate that:(1)The local damage to the slab by the plane hammer is readily apparent,while the overall damage by the spherical hammer is more pronounced.(2)In comparison to the high reinforcement ratio slabs,the overall bending resistance of the low reinforcement ratio slabs is significantly inferior,and the slab back exhibits further cracks.(3)As the hammer height increases,the slab failure mode undergoes a transformation,shifting from local failure by stamping and overall failure by stamping to local-overall coupling failure and local failure by punching.(4)Three failure mode thresholds have been established,and by comparing the peak impact force with the failure thresholds,the failure mode of the slab can be effectively determined.展开更多
In order to accommodate higher speeds,heavier axle weights,and vibration damping criteria,a new floating slab structure was proposed.The new type of floating slab track structure was composed of three prefabricated fl...In order to accommodate higher speeds,heavier axle weights,and vibration damping criteria,a new floating slab structure was proposed.The new type of floating slab track structure was composed of three prefabricated floating slabs longitudinally interconnected with magnesium ammonium phosphate concrete(MPC).This study investigated the dynamic performance of the structure.We constructd a full-scale indoor experimental model to scrutinize the disparities in the impact performance between a longitudinally connected floating slab track and its longitudinally disconnected counterpart.Additionally,a long-term fatigue experiment was conducted to assess the impact performance of longitudinally connected floating slab tracks under fatigue loading.The findings are described in the following.1)The new structure effectively suppresses ground vibrations,exhibiting a well-balanced energy distribution profile.However,the imposition of fatigue loading leads to a reduction in the damping performance of the steel spring damping system,thereby reducing its capacity to attenuate structural vibrations and leading to an increase in ground vibration energy;2)After 107 loading cycles,the attenuation rate of the vibration acceleration for the MPC increases by 171.9%.Conversely,at the corresponding disconnected location,the attenuation rate of ground vibration acceleration decreases by 65.6%.In conclusion,longitudinally connected floating slab tracks exhibit superior vibration reduction performance.While the vibration reduction performance of longitudinally connected floating slab tracks may diminish to some extent during long-term service,these tracks continue to meet specific vibration reduction requirements.展开更多
基金Supported by the National Natural Science Foundation of China(Grant No.52078283)Shandong Provincial Natural Science Foundation(Project No.ZR2024MA094)。
文摘With the change of the main influencing factors such as structural configuration and impact conditions,reinforced concrete slabs exhibit different mechanical behaviors with different failure patterns,and the failure modes are transformed.In order to reveal the failure mode and transformation rule of reinforced concrete slabs under impact loads,a dynamic impact response test was carried out using a drop hammer test device.The dynamic data pertaining to the impact force,support reaction force,structural displacement,and reinforcement strain were obtained through the use of digital image correlation technology(DIC),impact force measurement,and strain measurement.The analysis of the ultimate damage state of the reinforced concrete slab identified four distinct types of impact failure modes:local failure by stamping,overall failure by stamping,local-overall coupling failure,and local failure by punching.Additionally,the influence laws of hammerhead shape,hammer height,and reinforcement ratio on the dynamic response and failure mode transformation of the slab were revealed.The results indicate that:(1)The local damage to the slab by the plane hammer is readily apparent,while the overall damage by the spherical hammer is more pronounced.(2)In comparison to the high reinforcement ratio slabs,the overall bending resistance of the low reinforcement ratio slabs is significantly inferior,and the slab back exhibits further cracks.(3)As the hammer height increases,the slab failure mode undergoes a transformation,shifting from local failure by stamping and overall failure by stamping to local-overall coupling failure and local failure by punching.(4)Three failure mode thresholds have been established,and by comparing the peak impact force with the failure thresholds,the failure mode of the slab can be effectively determined.
基金Project(2022-Major-14)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘In order to accommodate higher speeds,heavier axle weights,and vibration damping criteria,a new floating slab structure was proposed.The new type of floating slab track structure was composed of three prefabricated floating slabs longitudinally interconnected with magnesium ammonium phosphate concrete(MPC).This study investigated the dynamic performance of the structure.We constructd a full-scale indoor experimental model to scrutinize the disparities in the impact performance between a longitudinally connected floating slab track and its longitudinally disconnected counterpart.Additionally,a long-term fatigue experiment was conducted to assess the impact performance of longitudinally connected floating slab tracks under fatigue loading.The findings are described in the following.1)The new structure effectively suppresses ground vibrations,exhibiting a well-balanced energy distribution profile.However,the imposition of fatigue loading leads to a reduction in the damping performance of the steel spring damping system,thereby reducing its capacity to attenuate structural vibrations and leading to an increase in ground vibration energy;2)After 107 loading cycles,the attenuation rate of the vibration acceleration for the MPC increases by 171.9%.Conversely,at the corresponding disconnected location,the attenuation rate of ground vibration acceleration decreases by 65.6%.In conclusion,longitudinally connected floating slab tracks exhibit superior vibration reduction performance.While the vibration reduction performance of longitudinally connected floating slab tracks may diminish to some extent during long-term service,these tracks continue to meet specific vibration reduction requirements.
