Natural ventilation arc structure has good structural strength, this strength does not need to rely on large size steel structure of the elephant shed skylight that realized, thus greatly reduces the weight of the body. The design specifications of the ventilator, relying on the support member of the building, in addition to considering the wind and snow load, earthquake effect, in fact support plant structure mostly for roof load service.
So, the ventilator component material specification selection is very important, first of all should be fully meet the requirements of snow load, but also to avoid unnecessary selection of large specifications, to avoid increasing the deadweight cost increase, workshop roof load and increase.
Material Science：
(1) the color plate is generally 0.5mm aluminum zinc coated sheet as a ventilator shield and rain intensity is 280Mpa, both sides of timber, aluminum zinc content is more than 150g, the film thickness is 22-25um positive, on the back of 15mu, the board is characterized with good corrosion resistance.
Fluorocarbon version: fluorocarbon version because of its high price, generally used in high corrosion workshop. Fluorocarbon coating is polytetrafluoroethylene (PTFE) with tiny particles dispersed in a solvent, and then by high temperature sintering 360-380oC film, the coating can be used in -195--250oC for a long time, the chemical resistance over all polymers. Aluminum zinc coated sheet is anticorrosive fluorocarbon shielding plate of the most ideal.
welding
(1) welding material has a great influence on the quality of welded steel structure. For the entry of the qualified welding materials, the production date of the product, the preservation of the state, the use of baking, also directly affect the quality of welding, must be used in accordance with national standards of welding materials.
(2) considering the weld quality grade with ventilator load requirements, which seriously affect the bearing capacity of the weld defects are prohibited, to deal with the serious impact on the appearance of weld quality for the carrying capacity of the requirements included in the main control program, and gives the appearance of qualified quality requirements. The surface porosity, slag inclusion and arc pit cracks are not allowed to exist, and the defects such as undercut, incomplete welding, root shrinkage and so on have great influence on the dynamic load.
In order to reduce the stress concentration and improve the ability of the joint to bear the fatigue load, some of the fillet welds are made into V. This type of joint must pay attention to the smooth transition between the weld and base metal. At the same time, the influence of weld size should be taken into consideration when determining the weld thickness
8.2 assembly - fastener connection
Connect the ventilator base and the arc, should choose phi is more than or equal to 16mm high strength bolt; the connecting member of other parts of the body, use galvanized bolt connection phi is more than or equal to 10mm. Drilling should be accurate, forced through the bolt will damage the threads and the change of high strength bolt torque coefficient of side connection, even the nuts are not screwed on, so that free penetration bolt hole. Gas cutting hole is very irregular, not only weakened the effective cross section, reducing the pressure force transmission area, will make the steel defects at the hole. So, the ventilator installation shall be using gas cutting hole. The limitation of the connection aperture should be based on the consideration of the effective load surface and the frictional force transfer area.
Assembly bolts shall be securely connected