Wind Load Criteria Research Articles

Structural-equivalent mean recurrence intervals for NESC Rule 250B

Overhead lines in the United States are currently designed based on both deterministic and probabilistic loading concepts for ice and wind. These load cases are specified in the National Electrical Safety Code (NESC) (Institute of Electrical and Electronics Engineers, Inc. (IEEE), 2023). The deterministic loads for the continental United States are based on three loading districts: light, medium, and heavy, and the corresponding loads based on the specified weather criteria are to be used with specified structural load factors. In practice, the factored deterministic loads often control the design of a structure compared to the probabilistic loads which apply a load factor of 1.0. Furthermore, the deterministic loads are not associated with a Mean Recurrence Interval (MRI), thereby making the assessment of the reliability index cumbersome for structures controlled by these loads. A method to determine an equivalent MRI for these deterministic loads is presented, which involves associating the factored deterministic loads with a probability of exceedance based on location for ice and wind loads. The method is applied to a 230 kV transmission line including seven structure types and line angles, and for 26 locations across the continental United States, and a comparison of the equivalent MRI based on the deterministic loads is made to the probabilistic loads. Trends are presented which illustrate that the resulting equivalent MRI vary significantly among location and structure types. The findings highlight that different structure types of the same transmission line are associated with a wide range of equivalent MRI. Discussion is provided on the trends observed in case study and the inconsistency in structural reliability that could result from the application of deterministic ice and wind load criteria in NESC Rule 250B. It is not the intent of this paper to state what design MRIs are needed to ensure adequate reliability. The intent of this paper is to determine what range of structural equivalent MRIs overhead lines in the United States are currently designed to withstand.

Evaluation of various national greenhouse design standards for wind loading

The greenhouse design standard for South Korea is under revision to ensure the structural safety of greenhouses in response to strong winds. In order to ensure that suitable design standards for structural safety are adopted, wind load criteria for a range of countries have been analysed. The provisions for wind load, correction factors, and wind pressure coefficients were analysed using greenhouse design standards from Korea, China, Japan, United States of America (USA), and European Union (EU) (CEN, 2001; JGHA, 2016; MAFRA, 1999; MOHURD, 2017; NGMA, 2004). Although the calculations are similar throughout these greenhouse design standards (CEN, 2001; JGHA, 2016; MAFRA, 1999; MOHURD, 2017; NGMA, 2004), different factors are used to calculate wind load. From the analysed data, a structural analysis was conducted to evaluate the structural safety of the designs for wind load. The results indicated that a relatively rigid member should be used for a greenhouse framework constructed using the greenhouse design standard from USA (NGMA, 2004) and that a relatively inexpensive greenhouse could be constructed using the greenhouse design standard from Japan (JGHA, 2016).

Comparative Analysis of Sino-Foreign Wind Load Standard

It has great significanceto conduct comparative analysis on wind load criteria at home and abroad forimproving anti-wind load capacity of the structure. A brief overview of Chinese,American, European and Australia wind load design codes of structure ispresented in this paper. The difference among these wind load codes, theadvantages and disadvantages of Chinese related standards are pointed out.Through comparison of wind load standard between Chinese code and otherstandards, through learning from foreign experience about the determination ofwind load criteria, improvement of wind load of electrical equipment andstandard revised recommendations are provided.

WIND TUNNEL TEST FOR CALCULATING WIND FORCES ON SCAFFOLDS WITH BASEBOARD HEIGHT AS A PARAMETER

The Japanese Industrial Safety and Health Law was revised in March 2009 to introduce new measures concerning accidental falls in the construction industry. This revision mandates the use of guard rails, handrails, and other scaffold components. The wind load criteria and structural specifications of scaffolds are regulated by current design codes. Nevertheless, these provisions do not necessarily comply with the newly incorporated legal requirements because they apply to old-style scaffolds. This study examined the wind force on scaffolds by wind tunnel test, with baseboard height used as a parameter. The wind force coefficient of one story of scaffolds was calculated. Wind force coefficient increased as baseboard height increased. The wind force on the scaffolds equipped with baseboards is 9.2 times that on the scaffolds without baseboards. The baseboard must be greater than or equal to 15 cm to satisfy regulation requirements. The wind force coefficient of scaffolds with a 15 cm baseboard is 1.5 times that of the scaffolds without a baseboard. In scaffold design, baseboard height should be considered to guarantee a suitable wind force coefficient.

Study on Wind Load about Rotary Reticulated Shell by the Wind Tunnel Experiment

This paper is to study the wind load of rotary reticulated shell by experimental methods. The article conduct rigid model experiments to reticulated shell, measure wind pressure distribution on shell’top. Similar conditions is to meet production model:geometric similarity,flow similarity , Reynolds number equal. These results can be used as a reference for the new version of the wind load criteria.

Numerical Simulation of Pressure Distribution around the Reticulated Shell Structure with Large Span

In order to investigate the pressure distribution around the reticulated shell structure with large span, a commercial Computational Fluid Dynamic software Fluent is employed to obtain the wind load and the coefficients of the time averaged pressure distribution around the reticulated shell structure in this paper. The numerical simulations of surface pressure are consistent with the experimental results. The characteristics of the wind pressure distribution are described through the flow analysis around the reticulated shell structure. All these discoveries can be used as a reference for the new version of the wind load criteria.

Numerical Analysis on the Pressure Distribution of Long Oblate Chimney

In order to investigate wind load for long oblate chimney, a commercial computational software “Fluent” was employed to solve the time-averaged k-ε turbulent flow model for Realizable form. The flow structure and surface pressure distribution on the long oblate chimney upon facing wind was obtained for the wide-face and the narrow-face, respectively. The windward side of long oblate chimneys bears positive pressure, while the largest negative pressure area is on both sides of chimney. The characteristics of the wind pressure distribution were explained by analyzing the flow around the chimney. These discoveries can be used as a reference, for the new version of the wind load criteria.

A review of standards of practice for wind resistant manufactured housing

Each year significant damage to manufactured housing is produced by straight winds, hurricanes, and tornadoes. Damage is primarily in the form of roof failure and tiedown/foundation failures. Initiation of these failures sometimes leads to sudden and total destruction of manufactured homes. Wind load criteria and construction practices are examined in this paper. Strategies are presented for improving wind resistance of manufactured homes, one of which is to ultimately abandon the use of ground anchors and adopt the use of permanent foundations.