Engineering

Specifications

All G&S columns are designed and manufactured in accordance with Australian Standards. When designing a column we take into account numerous factors that will have a direct effect on the design engineering and manufacturing of the product.

• A) The Importance Level of the structure is determined in accordance with its occupancy and use. It is determined in accordance with Australian Standard AS1170.0 and is a process of determining the consequences of failure of the column. This will have a direct effect on the design engineering of the column.
  
  
• B) The Geographical Installation Location of the column. Eg Wind Region A, B, C or D. This will have a direct effect on the wind loadings on the column as wind speeds differ from region to region.
  
  
• C) The Terrain Category of the installation site. The terrain category rating indicates the obstructions or surface roughness associated with the particular terrain, which will have a direct effect on the wind loading on the column and it's operating equipment. Selection of the terrain category is made with due regard to the permanence of the obstructions that constitute the surface roughness. For example, the vegetation in a tropical cyclonic region should not be relied upon in assessing the surface roughness during a wind event. Typically, the larger the obstructions surrounding the installation site, the less the wind loading on the column and vice versa. The theory being that the terrain obstruction will have a shielding effect and thereby reduce the wind loading on the column and its operating equipment.
  
  
• D) The Total Combined Sail Area of the lighting or other equipment to be installed on the column. For each separate light fitting or item of equipment, the largest single surface area is taken into account in assessing the item's sail area.
   
• E) The Mounting Height of the lighting or other equipment on the column.
  
  
• F) The Total Combined Sail Weight of the lighting or other equipment and the headframe.
  
  
• G) The Sail Offset from the column centre. For example, if the sail area and weight is offset on one side of the column in an unbalanced fashion, this will affect the loading on the column.
  
  
• H) Topographical Multiplier - Wind velocities increase by up to 70% in the vicinity of hills and ridges. This is incorporated into the design by the use of a topographic multiplier which takes into account the slope of the land, the height of the crest, the distance of the pole from the crest, and whether the pole is upwind or downwind of the crest.
  
  
• I) Shielding Multiplier - Where poles are located in close proximity to other structures, shielding effects reduce wind speeds by up to 30%. A shielding factor can be determined for a given wind direction based on the height, width and proximity of adjacent structures. It is important to be confident that any structures assumed to provide shielding will be present for the life of the column.
  
  
• J) Directional Multiplier - In locations not exposed to cyclones, the direction of maximum wind velocities can be predicted. For example, in Melbourne, maximum wind velocities from the south east are only 80% of those from the north. Poles with fittings with wind areas which are greater in one direction than the another may be of benefit if the orientation of the fittings is known.
  
  
• K) Annual Probability Of Exceedance - This is the probability that a wind speed will be exceeded in any one year and is the inverse of the "Wind Return Period" or the average recurrence interval. The wind speed for a long wind return period (eg 500 years) will be significantly higher than the wind speed for a short wind return period. Australian Standards give guidance on the selection of a return period for wind loading based on the importance of the structure and its design life. An important structure with a long design life will be designed for a longer return period and thus higher wind speed.
  
  
• L) The Soil Conditions of the installation location - The soil conditions at the column installation site will influence the size and type of footing selected. For example, course sand soils have more than twice the bearing capacity of silty clay soils, leading to more compact pile and square pad footings.
  
  
• M) The Design Life of the product. This is the duration of the period during which the structure is assumed to perform for its intended purpose with expected maintenance but without major structural repair being necessary.
  
  
• N) Operational Parameters of mounting equipment, eg. communication equipment, CCTV equipment, lighting and other equipment. Eg. Deflection criteria for a camera or operating beam width of an antenna.
  
  
• O)  Any Required Design Redundancy required in the product. This includes client requests for the column to have the capability of carrying a greater sail area and sail weight the initial setup configuration. In this case the column will be designed to the clients' specifications.

  G&S Industries take into account all the above factors in designing safe working columns to meet our clients' specific requirements. Using our computerised engineering analysis programs, we can design and engineer a column to suit any combination of the above factors.