Large amplitude vibration of mast arm structures due to wind loads are the primary contributing factor to the reduced fatigue life of signal support structures. To alleviate this problem of wind-induced in-plane vibra...Large amplitude vibration of mast arm structures due to wind loads are the primary contributing factor to the reduced fatigue life of signal support structures. To alleviate this problem of wind-induced in-plane vibration of mast arm signal structures, a particle-thrust damping based turned mass damper(PTD-TMD) device is adopted and its damping effect is characterized experimentally. The particle-thrust damping is a passive damping device that does not require electric power and is temperature independent. Based on the calibration test, an equivalent dynamic model of the PTD-TMD device is developed and used for numerical simulation study. The damping effects of this PTD-TMD device on signal support structures was investigated through both numerical analysis and laboratory testing of a 50-ft(15.24 m) mast arm structure including both free vibration and forced vibration tests. The experimental test and numerical study results show that vibration response behavior of mast arm signal support structures can be significantly reduced by installing the PTD-TMD that can increase the critical damping ratio of the mast arm signal structures to 4%. The stress range at the welded connection between the mast arm and traffic pole is also reduced.展开更多
With high stability,strong bearing capacity and other characteristics,multi-point leveling systems have been widely used in various industries.The mobile platform here uses a 12-point leveling system,which is mainly c...With high stability,strong bearing capacity and other characteristics,multi-point leveling systems have been widely used in various industries.The mobile platform here uses a 12-point leveling system,which is mainly composed of the mechanical transmission system of the supporting arm,a hydraulic drive system and an electrical control system.The leveling is realized through the proportional lifting of the arms in four quadrants.In order to ensure the smooth conduct of launch missions,emergency plans were made for the leveling system incase of failure of a single arm.展开更多
基金partially supported through a research grant from Maryland State Highway Administration (MdSHA) and National Transportation Research Center at University of Maryland
文摘Large amplitude vibration of mast arm structures due to wind loads are the primary contributing factor to the reduced fatigue life of signal support structures. To alleviate this problem of wind-induced in-plane vibration of mast arm signal structures, a particle-thrust damping based turned mass damper(PTD-TMD) device is adopted and its damping effect is characterized experimentally. The particle-thrust damping is a passive damping device that does not require electric power and is temperature independent. Based on the calibration test, an equivalent dynamic model of the PTD-TMD device is developed and used for numerical simulation study. The damping effects of this PTD-TMD device on signal support structures was investigated through both numerical analysis and laboratory testing of a 50-ft(15.24 m) mast arm structure including both free vibration and forced vibration tests. The experimental test and numerical study results show that vibration response behavior of mast arm signal support structures can be significantly reduced by installing the PTD-TMD that can increase the critical damping ratio of the mast arm signal structures to 4%. The stress range at the welded connection between the mast arm and traffic pole is also reduced.
文摘With high stability,strong bearing capacity and other characteristics,multi-point leveling systems have been widely used in various industries.The mobile platform here uses a 12-point leveling system,which is mainly composed of the mechanical transmission system of the supporting arm,a hydraulic drive system and an electrical control system.The leveling is realized through the proportional lifting of the arms in four quadrants.In order to ensure the smooth conduct of launch missions,emergency plans were made for the leveling system incase of failure of a single arm.
