Overhead sign-support bridges that allow displaying necessary information for travelers across the multiple lanes in highways often use large message sign panels: static message sign (SMS) panels or dynamic message si...Overhead sign-support bridges that allow displaying necessary information for travelers across the multiple lanes in highways often use large message sign panels: static message sign (SMS) panels or dynamic message sign (DMS) panels. Along with conventional SMS panel, the use of DMS panel is increasing in highways over time owing to their effective capability to guide the travelers in real-time. A 230-ft long span 4-chord overhead steel truss bridge attached with SMS and DMS panel has been studied through extensive finite element analysis to observe the structural integrity. The static wind load was applied in model truss for four different configurations as per 2016 AASHTO LRFD design specification. The innovative structural detailing approach for truss end support and connection detailing for toll-equipment supporting frame was proposed based on static analysis. The present study will help engineers to design overhead sign support bridges by ensuring both public safety and structural integrity.展开更多
To evaluate the importance of the canyon topography effects on large structures, based on a rigid frame bridge across a 137-m-deep and 600-m-wide canyon, the seismic response of the canyon site is analyzed using a two...To evaluate the importance of the canyon topography effects on large structures, based on a rigid frame bridge across a 137-m-deep and 600-m-wide canyon, the seismic response of the canyon site is analyzed using a two-dimensional finite element model under different seismic SV waves with the assumptions of vertical incidence and oblique incidence to obtain the ground motions, which are used as the excitation input on the pier foundations of the bridge with improved large mass method. The results indicate that canyon topography has significant influences on the ground motions in terms of inci- dent angle. The peak ground acceleration values vary greatly from the bottom of the canyon to the upper comers. Under ver- tical incident SV waves, at the upper comers of canyon the peak ground accelerations greatly increase; whereas the peak ground accelerations diminish at the bottom comers of canyon. Under oblique incident SV waves, the shaking of the canyon slope perpendicular to the incidence direction is much more severe than that of the opposite side of canyon. And the ground surface has been characterized by larger deformations in the case of oblique incident waves. It is also concluded that the low piers and frame of the continuous rigid frame bridge ape more sensitive to the multi-support seismic excitations than the flexible high piers. The canyon topography as well as the oblique incidence of the waves brings the continuous rigid frame bridge severe responses, which should be taken into account in bridge design.展开更多
文摘Overhead sign-support bridges that allow displaying necessary information for travelers across the multiple lanes in highways often use large message sign panels: static message sign (SMS) panels or dynamic message sign (DMS) panels. Along with conventional SMS panel, the use of DMS panel is increasing in highways over time owing to their effective capability to guide the travelers in real-time. A 230-ft long span 4-chord overhead steel truss bridge attached with SMS and DMS panel has been studied through extensive finite element analysis to observe the structural integrity. The static wind load was applied in model truss for four different configurations as per 2016 AASHTO LRFD design specification. The innovative structural detailing approach for truss end support and connection detailing for toll-equipment supporting frame was proposed based on static analysis. The present study will help engineers to design overhead sign support bridges by ensuring both public safety and structural integrity.
基金supported by National Natural Science Foundation of China (No. 50708100)National Science and Technology Support Project of China (No. 2006BAC13B02)partially by Basic Research Program of Institute of Mechanics Engineering, China Earthquake Administration (No. 2007B02)
文摘To evaluate the importance of the canyon topography effects on large structures, based on a rigid frame bridge across a 137-m-deep and 600-m-wide canyon, the seismic response of the canyon site is analyzed using a two-dimensional finite element model under different seismic SV waves with the assumptions of vertical incidence and oblique incidence to obtain the ground motions, which are used as the excitation input on the pier foundations of the bridge with improved large mass method. The results indicate that canyon topography has significant influences on the ground motions in terms of inci- dent angle. The peak ground acceleration values vary greatly from the bottom of the canyon to the upper comers. Under ver- tical incident SV waves, at the upper comers of canyon the peak ground accelerations greatly increase; whereas the peak ground accelerations diminish at the bottom comers of canyon. Under oblique incident SV waves, the shaking of the canyon slope perpendicular to the incidence direction is much more severe than that of the opposite side of canyon. And the ground surface has been characterized by larger deformations in the case of oblique incident waves. It is also concluded that the low piers and frame of the continuous rigid frame bridge ape more sensitive to the multi-support seismic excitations than the flexible high piers. The canyon topography as well as the oblique incidence of the waves brings the continuous rigid frame bridge severe responses, which should be taken into account in bridge design.
