Wind Load Provisions in 2001 AASHTO Supports Specifications

2003 ◽  
Vol 1845 (1) ◽  
pp. 10-18
Author(s):  
Fouad H. Fouad ◽  
Elizabeth Calvert
Keyword(s):  
Major Part ◽  
Traffic Signals ◽  
Structure Type ◽  
Wind Load ◽  
Wind Pressure ◽  
Major Research ◽  
National Cooperative ◽  
Departments Of Transportation ◽  
Highway Signs ◽  
Highway Research

The AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals (Supports Specifications) has been revised in its entirety through a major research project conducted under the auspices of the National Cooperative Highway Research Program (NCHRP Project 17-10). The new document was approved in 1999 by all state departments of transportation for adoption by AASHTO and was published in 2001. A major part of the revisions included new provisions and criteria for wind loads. These provisions differ considerably from those in previous editions of the specifications. A review of the changes in the wind load provisions of the 2001 Supports Specifications is presented. These changes, which are primarily due to the adoption of a new wind speed map based on a 3-s gust, could result in a significant increase in the magnitude of wind pressure in hurricane areas and a decrease in inland areas depending on location and structure type.

Mitigating Fatigue in Cantilevered Overhead Sign Structures

2015 ◽  
Vol 2522 (1) ◽  
pp. 18-26
Author(s):  
Mohamed S. Gallow ◽  
Fouad H. Fouad ◽  
Ian E. Hosch
Keyword(s):  
Structural Design ◽  
Endurance Limit ◽  
Time History ◽  
Traffic Signals ◽  
The United States ◽  
Wind Pressure ◽  
Wind Gusts ◽  
Power Spectral ◽  
Highway Signs ◽  
Fatigue Endurance

Cantilevered overhead sign structures (COSSs) are widely used across highways in the United States. Several cases of excessive vibrations and failures caused by fatigue wind loads from natural and truck-induced wind gusts have been reported. Not enough research has included the effect of making structural design modifications on the fatigue performance of COSSs. Under fatigue wind-induced loads, the dynamic characteristics (frequency and damping) of COSSs are important parameters affecting their structural behavior. When frequencies of wind load and the structure match, resonance may occur, causing excessive vibrations, depending on the frequency value. If accompanied fatigue stresses exceed the fatigue endurance limit, failure occurs after a certain number of loading cycles. The objective of this study was to investigate stiffness and mass distribution of COSSs to control the structural frequency, thus mitigating fatigue caused by wind-induced gusts. For this purpose, modifications in the members' shape, arrangement, size, and layout of structure were examined. Three layouts were compared: four-chord, two-chord, and monotube COSSs. These layouts were designed according to the 2013 AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals and modeled with SAP2000. Wind pressure power spectral density and time history loading functions were applied to these structures to simulate natural and truck-induced wind gusts, respectively. Results showed that the vertical mono-tube COSS design with curved end post had the least mass, but fatigue stresses were comparable with the four-chord COSS. The two-chord COSS design had the largest mass and exhibited the highest fatigue stresses.

Wind Pressure and Wind-Induced Vibration of Heliostat

2008 ◽  
Vol 400-402 ◽  
pp. 935-940 ◽  
Author(s):  
Ying Ge Wang ◽  
Zheng Nong Li ◽  
Bo Gong ◽  
Qiu Sheng Li
Keyword(s):  
Dynamic Response ◽  
Wind Direction ◽  
Wind Load ◽  
Wind Pressure ◽  
Induced Response ◽  
Vertical Angle ◽  
Lateral Direction ◽  
Direction Angle ◽  
Wind Pressures ◽  
Fluctuating Wind

Heliostat is the key part of Solar Tower power station, which requires extremely high accuracy in use. But it’s sensitive to gust because of its light structure, so effect of wind load should be taken into account in design. Since structure of heliostat is unusual and different from common ones, experimental investigation on rigid heliostat model using technology of surface pressure mensuration to test 3-dimensional wind loads in wind tunnel was conducted. The paper illustrates distribution and characteristics of reflector’s mean and fluctuating wind pressure while wind direction angle varied from 0° to 180° and vertical angle varied from 0° to 90°. Moreover, a finite element model was constructed to perform calculation on wind-induced dynamic response. The results show that the wind load power spectral change rulers are influenced by longitudinal wind turbulence and vortex and are related with Strouhal number; the fluctuating wind pressures between face and back mainly appear positive correlation, and the correlation coefficients at longitudinal wind direction are smaller than those at lateral direction; the fluctuating wind pressures preferably agree with Gaussian distribution at smaller vertical angle and wind direction angle. The wind-induced response and its spectrums reveal that: when vertical angle is small, the background responsive values of reflector’s different parts are approximately similar; in addition, multi-phased resonant response occurring at the bottom. With the increase of , airflow separates at the near side and reunites at the other, as produces vortex which enhances dynamic response at the upper part.

Determination of Basic Wind Velocity for Wind Load-Governed Limit State

2019 ◽  
Author(s):  
Ji Hyeon Kim ◽  
Hae-Sung Lee
Keyword(s):  
Wind Velocity ◽  
Reliability Index ◽  
General Procedure ◽  
Limit State ◽  
Wind Load ◽  
Wind Pressure ◽  
Load Factor ◽  
Load Effect ◽  
Design Life ◽  
Target Reliability Index

<p>This paper proposes a general procedure for evaluating a nominal value of wind velocity for a wind load- governed limit state to secure a target reliability index during the design life of a structure. The nominal value of wind velocity, referred to as a basic wind velocity, and wind load factor should be determined so that the factored wind load effect secures a target reliability index for a wind load-governed limit state. In this study, the analytical form of the return period of the basic wind velocity is expressed as a function of the target reliability index, wind load factor, and statistical parameters of wind pressure, which are derived as linear functions of the coefficient of wind velocity. The proposed approach is applied to the Korean Highway Bridge Design Code-Cable supported Bridge, which specifies the design life of a structure as 100- and 200-year.</p>

INTERNAL FORCES IN THE FRAME OF BUILDING OF PRISMATIC FORM UNDER DIFFERENT DISTRIBUTION OF WIND PRESSURE

2021 ◽  
Vol 97 (5) ◽  
pp. 31-39
Author(s):  
V.S. KUZNETSOV ◽  
◽  
A.A. SHURUSHKIN ◽  
Keyword(s):  
Russian Federation ◽  
Research Method ◽  
Relevant Information ◽  
Wind Load ◽  
Building Codes ◽  
Wind Pressure ◽  
Regulatory Documents ◽  
Internal Forces ◽  
The Russian Federation ◽  
Graphic Interpretation

The features of the effect of wind on a prismatic-type building with different methods of determining the coefficient of wind pressure along the height are considered. The study was carried out on the basis of studying the main provisions of regulatory documents governing design and development activities in the Russian Federation, as well as current publications of domestic and foreign scientists, corresponding to research in this area. The research method is structural and analytical analysis using the correlation dependences of the factors under study. Analytical dependencies for determining the wind forces for various methods of assigning the wind load coefficient along the height of the building and their graphic interpretation are given. The work is based on the provisions of domestic building codes and relevant information contained in other domestic and foreign sources. For prismatic buildings with a height of up to 80 meters, there are areas where the forces from the main wind load significantly depend on the method of its determination. The conducted research indicates the ambiguity used in the practice of designing the parameters of the wind load, allowing the possibility of excess or underloading of structures or individual elements.

Wind Force on Tall Structure: An Approach From SPH

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Ananna Ahmed ◽  
Abdullah Hil Baki ◽  
Munaz Ahmed Noor
Keyword(s):  
Structural Engineering ◽  
Model Simulation ◽  
Wind Load ◽  
Tall Building ◽  
Test Method ◽  
Wind Pressure ◽  
Wind Force ◽  
Wide Range ◽  
Particle Hydrodynamics ◽  
Tall Structure

Wind pressure calculation for tall building frame has always been an extensive job. Usual methods used to estimate wind load are Wind tunnel test method and Finite Element Method and specifications has been derived. In this research, with a view to eliminating drawbacks of these methods and providing a visual interpretation of wind flow a third method is introduced using Smooth Particle Hydrodynamics (SPH) Approach. A model simulation was performed by a SPH software named SPHysics to calculate the pressure exerted on the structure and to derive a graphical interpretation of flow pattern using Para View. Values of pressure at different elevation of the building that actually occurs when wind with certain velocity flows through a tall building are found. From the data found, height vs. pressure graphs are generated which clearly supports the proportional relationship between these two parameters even with triangular and parabolic variation. Again, velocity vs. pressure graphs are plotted which also justifies inter-relationship of proportionality. This is a qualitative comparison not a quantitative one as there is many limitations regarding technicality, computer capacity, and time. These values may be crosschecked with the values found from conventional methods when more precise and suitable boundary conditions can be used in simulation. In future, with intricate detailing and suitable three dimensional modeling, more accurate value of pressure can be found with wide range of applicability. The authors are expecting derivation of two equations as a function of height and velocity to calculate wind load to use in design if further proceeding is possible. This can offer a significant benefit of simplicity for users and can be beginning a new era of using SPH in structural engineering.   Keywords - Wind force, tall structure, Particle Hydrodynamics Approach

Correlation and Combination Factors of Wind Forces on Cylindrical Roof Structures

2017 ◽  
Vol 17 (09) ◽  
pp. 1750104 ◽  
Author(s):  
Bo Chen ◽  
Pengpeng Zhong ◽  
Weihua Cheng ◽  
Xinzhong Chen ◽  
Qingshan Yang
Keyword(s):  
Side Wall ◽  
Single Layer ◽  
Correlation Coefficients ◽  
Wind Load ◽  
Wind Pressure ◽  
Wind Loads ◽  
Horizontal Wind ◽  
Parameter Study ◽  
Response Component ◽  
Wind Pressures

The correlations among wind pressures on roof and walls are examined for the cylindrical roof buildings with different rise-span ratios based on wind tunnel data. Wind-induced dynamic response is also analyzed with a parametric study concerning span length, rise-span ratio, stiffness of supporting frames and connection type between roof and supporting frames, where the roof system is a single-layer cylindrical reticular shell. For both roof and supporting frames, the responses induced by vertical wind loads on the roof and by horizontal wind loads on the walls are investigated. The correlation coefficients of these response components are examined. The results showed that the fluctuating wind pressure on the roof is strongly correlated with the wind pressure on the side wall and the leeward wall, but weakly correlated with the wind pressure on the windward wall. The response of roof and supporting frames caused by the wind loads on the roof is much larger than that of wind loads on the walls. On the bases of a comprehensive parameter study and complete quadratic combination (CQC) rule, a practical simplified combination rule is suggested for estimating response of roof and supporting frames. It is given as sum of response component caused by wind load on roof and that of wind load on walls multiplied with a combination factor of [Formula: see text].

scholarly journals Genetic Algorithm for Multiple Bus Line Coordination on Urban Arterial

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zhen Yang ◽  
Wei Wang ◽  
Shuyan Chen ◽  
Haoyang Ding ◽  
Xiaowei Li
Keyword(s):  
Genetic Algorithm ◽  
Travel Time ◽  
Public Transport ◽  
Major Part ◽  
Traffic Signals ◽  
Traffic Efficiency ◽  
Road Section ◽  
Bus Travel Time ◽  
The City ◽  
Urban Arterial

Bus travel time on road section is defined and analyzed with the effect of multiple bus lines. An analytical model is formulated to calculate the total red time a bus encounters when travelling along the arterial. Genetic algorithm is used to optimize the offset scheme of traffic signals to minimize the total red time that all bus lines encounter in two directions of the arterial. The model and algorithm are applied to the major part ofZhongshan NorthStreet in the city of Nanjing. The results show that the methods in this paper can reduce total red time of all the bus lines by 31.9% on the object arterial and thus improve the traffic efficiency of the whole arterial and promote public transport priority.

Micro-Deval Testing of Aggregates in the Southeast

2003 ◽  
Vol 1837 (1) ◽  
pp. 73-79 ◽  
Author(s):  
L. Allen Cooley ◽  
Robert S. James
Keyword(s):  
Los Angeles ◽  
Magnesium Sulfate ◽  
Impact Test ◽  
Southeastern United States ◽  
Test Results ◽  
Performance Category ◽  
Los Angeles Abrasion ◽  
National Cooperative ◽  
Highway Research

Aggregate used in hot-mix asphalt (HMA) must be tough and durable, not only to withstand the effects of HMA production, transportation, and construction but also to resist the effects of traffic and the environment. Historically, the Los Angeles abrasion and impact test has determined the toughness of aggregates. The long-term durability characteristics of aggregates are generally determined using a soundness test: sodium or magnesium sulfate. During the National Cooperative Highway Research Program’s Project 4–19, the micro-Deval test, in conjunction with the magnesium sulfate soundness test, were recommended in lieu of the Los Angeles abrasion and impact test and other soundness tests. Therefore, a study was needed within the southeastern United States to evaluate the range in micro-Deval results that could be expected. This research characterized the toughness and durability of aggregates with respect to their micro-Deval test results. Seventy-two aggregate sources from eight different states were included in this research. These aggregates were rated as good, fair, or poor with respect to performance by the contributing state. On the basis of the results of this study, some large differences were found in micro-Deval test results within a given performance category. There was no relationship between Los Angeles abrasion and impact and micro-Deval test results.

FSI Research on the Noise Barrier of High-Speed Railway in the Composite Conditions

2013 ◽  
Vol 307 ◽  
pp. 149-155
Author(s):  
Hong Chao Wang ◽  
Jin Fa Xie
Keyword(s):  
High Speed ◽  
Equivalent Stress ◽  
Wind Load ◽  
Wind Pressure ◽  
Fluid Distribution ◽  
Transient Dynamic Analysis ◽  
Obvious Effect ◽  
High Speed Railway ◽  
Noise Barrier ◽  
Natural Wind

Based on the model, it firstly gets the fluid distribution of noise barrier of high-speed railway, which is under the action of train-induced impulsive wind pressure and natural wind load, then transfers the computed result as exported load to the structural analysis module through the coupling interface, by proceeding the transient dynamic analysis and modal analysis, it finally obtains the equivalent stress, total deformation and modal distribution of noise barrier. The results indicate that, compared with train-induced impulsive wind pressure, the natural wind load has a more obvious effect on the structural performance of noise barrier, and its natural frequency is much less than the external load’s, so there will be no resonate happen in practice.

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