Download or read book Fatigue Loading of Cantilever Sign Structures from Truck Wind Gusts written by Bruce Montel Creamer and published by . This book was released on 1979 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue resistant Design of Cantilevered Signal Sign and Light Supports written by Robert Joseph Dexter and published by Transportation Research Board. This book was released on 2002 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mitigating Fatigue of Cantilevered Overhead Sign Structures Due to Natural and Truck induced Wind Gusts written by Mohamed Salah Gallow and published by . This book was released on 2014 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cantilevered overhead sign structures (COSS) are widely used across highways in the U.S. Several cases of failures have been reported for such structures due to fatigue wind loads. The structure's dynamic characteristics such as natural frequency and critical damping are responsible for its behavior during those loads. When the frequency of wind gusts load matches the fundamental frequency of the OSS, resonance occurs, which causes excessive vibrations. Consequently, fatigue stresses in crease and may exceed the fatigue critical limit, resulting in failure. Vibrations and fatigue stresses amplitudes are dependent on the structure's natural frequency. The objective of this study is investigating natural frequencies of COSS in order to mitigate fatigue stresses due to natural and truck-induced wind gusts. Investigating damping and other fatiguee wind loads are out of the scope in this study. Alterations in factors such as the members' configuration, arrangement, sizes, and layout of the structure control its stiffness and mass distribution which controls its natural frequency and consequently, fatigue stresses. A parametric study was considered in order to investigate the effect of these factors and recommend the best layout between 4-chord, 2-chord, and monotube CSS in mitigating fatigue. Structures were designed according to the American Association of State Highway and Transportation Officials (AASHTO) 2013, Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals (mentioned hereafter as the AASHTO Support Specifications (2013)) and modeled using commercial finite element analysis software. Wind pressure power spectral density and time history loading functions were applied on these structures to simulate natural and truck-induced wind gusts, respectively. Eventally, on the contrary of the 2-chord structure, slanted monotube CSS with curved end post was found to have least mass, highest frequency and nearly smallest fatigue stresses.
Download or read book Fatigue resistant Design of Cantilevered Signal Sign and Light Supports written by Mark R. Kaczinski and published by Transportation Research Board. This book was released on 1998 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Performance of Variable Message Sign Luminaire Support Structures Fatigue related wind loads on highway support structures written by Gary R. Consolazio and published by . This book was released on 1998 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes research which focused on determining equivalent static pressures for fatigue loads on cantilevered highway sign support structures. A cantilevered variable message sign (VMS) instrumented with strain gages, pressure transducers, and a wind sentry, was continuously monitored for three months. Short-term testing was conducted on the structure in order to determine the dynamic characteristics such as stiffness, natural frequency, and percent of critical damping. Long-term monitoring was performed to capture the structure's response to natural wind gusts, galloping, and truck-induced wind gusts.
Download or read book Field Testing of Cantilevered Traffic Signal Structures Under Truck induced Gust Loads written by and published by . This book was released on 2007 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structural Analysis of Sign Bridge Structures and Luminaire Supports written by and published by . This book was released on 2004 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Related Wind Loads on Highway Support Structures written by Kevin W. Johns and published by . This book was released on 1998 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Risks in the Connections of Sign Support Structures written by Christopher M. Foley and published by . This book was released on 2013 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Guide Design Specification for Bridge Temporary Works written by American Association of State Highway and Transportation Officials and published by AASHTO. This book was released on 1995 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Performance of Variable Message Sign Luminaire Support Structures written by Gary R. Consolazio and published by . This book was released on 1998 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Remaining Fatigue Life of a Non cantilever Highway Truss with Tubular Joints written by Abdullah Haroon and published by . This book was released on 2019 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: Non-cantilevered support structures have been widely used in the transportation department for supporting overhead traffic signs and signals. Several of them exhibit fracture failure at the welded connections, with the most likely cause being fatigue failure due to wind-induced vibrations. The failure usually occurs at "T", "Y", "K" tube to tube welded connections. The crack initiates at the welded junction of chord and diagonal and propagates circumferentially. A similar crack was observed at a truss on Alum Creek Drive at the interchange of I-270 in the state of Ohio. An investigation, funded by ODOT, was conducted at the University of Toledo into the cause of failure. Finite element modeling of the structure was conducted using SAP2000. External loadings from natural wind gusts were considered. It was presumed that the effects of other loadings such as vortex shedding, galloping, and truck gusts are negligible for this structure. Both static and transient dynamic analyses were performed. Weather data of daily variation in wind speed and direction were obtained from NCDC and a probabilistic wind distribution was performed. Using Kaimal spectrum load time histories of natural wind was generated, and a transient dynamic analysis was performed. Stress histories of critical members were extracted, and Palmgren-Miner rule was applied to evaluate the fatigue life of the critical members. The analysis results indicated that if the weld is assumed to be of sound quality, the fatigue life of the critical members under the effect of natural wind gust greater than the service life of the truss. Simulated damage scenarios were introduced by reducing the load carrying capacity of the members at failed joints and fatigue life was compared in undamaged and damaged states. Damage was introduced by reducing the mechanical strength of failed members and deterioration due to poor weld quality was not considered Compared to the undamaged state, the fatigue life in all the three damage scenarios was found to reduce by only 10%. This suggests that assuming the welds are done as per code requirements, the truss is redundant enough to sustain some damage without affecting the overall fatigue life of the structure. Even though the findings of this report predict the fatigue life to be greater than the service life of the truss, it should be noted that this result is only valid with the presumption that welded connections between members of the truss are sound and no defect in weld quality is considered in the present analysis. A quantitative assessment of the effects of weld defects on the fatigue life of the structure could give a better understanding of the failure mode, but such a venture was beyond the scope of this study.
Download or read book Structural Supports for Highway Signs Luminaires and Traffic Signals written by Fouad Hilmy Fouad and published by . This book was released on 1998 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Loading and Design Methodology for High Mast Lighting Towers written by Robert J. Connor and published by Transportation Research Board. This book was released on 2012 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB’s National Cooperative Highway Research Program (NCHRP) Report 718: Fatigue Loading and Design Methodology for High-Mast Lighting Towers provides criteria for the fatigue design of high-mast lighting towers.
Download or read book Dynamic Performance of Cantilevered Sign Trusses for Fatigue written by Hunter Senior and published by . This book was released on 2020 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cantilevered overhead sign structures (COSS) experience cyclic loading due to stochastic loads such as natural wind gusts (NWG). Wind loading can produce large deflections in the cantilever and large-magnitude stresses can develop at the box-type connection between the cantilevered arm and mast where fatigue performance is a concern. Modifications to the sign structures pose further concerns as changes to the aerodynamic properties could have unintended consequences. A design consideration of COSS is serviceability of the sign through use of a steel grate walkway that workers can use for maintenance on the sign. The steel grate walkways on COSS are rarely used for maintenance, and thus are being removed by multiple state DOTs to prevent vandalism. However, the impact on COSS with the removal of the walkways is unknown. This report describes an investigation in which the dynamic and aerodynamic properties of COSS were studied, and the effect of the walkway presence on structural response was explored. Computer simulations of 32 different COSS configurations were carried out to see the effect of the grate removal on the natural frequency and the mass of the overall structural system. Aerodynamic performance was considered through the use of computational fluid dynamics (CFD) and experimental testing, where wind pressure on the sign in both axial directions and effects of vortex shedding were examined. Findings include: 1) the walkway had a minimal effect on the system’s mass and natural frequencies, 2) the walkway had a minimal influence on the wind-induced force on the sign, 3) vortex shedding was not exacerbated with removal of a walkway attachment, and 4) walkway removal did not significantly change stress magnitudes at the connection between the cantilever and mast. Based on these findings, the removal of walkways from KDOT’s COSS was not found to be problematic.
Download or read book Wind Loading as a Fatigue Factor on Lighting Standard Mounting Bolts written by Kenneth O. Pinkerman and published by . This book was released on 1989 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vehicle induced Gust Loads on Aluminum Overhead Sign Structures written by Joseph B. Zell and published by . This book was released on 1977 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
