When using materials that shrink or swell with changes in moisture content and changes in relative humidity, it is important to consider a variety of implications whether the material is the only framing material employed or is used in combination with steel or other materials that do not exhibit the same changes in the presence of moisture. Dimensional stability concerns are magnified when materials are used in a mid-rise building. Although a material might be used successfully in low-rise buildings, the same construction practices cannot be assumed to be adequate for taller structures.
The best way to avoid dimensional stability problems is to build with a dimensionally-stable material such as steel. Steel structures provide long-term, consistent performance. Steel does not expand or contract with moisture content. Steel does not warp, split, crack or creep.
Steel is isotropic, meaning it has the same dimensional properties in all directions. When they get wet, both wood and brick will swell.
When they dry out and cure, concrete and concrete block will shrink and form shrinkage cracks. Using steel not only solves issues with structural movement due to changes in moisture content or humidity, but eliminates or greatly reduces other moisture related issues such as rot and mold.
Wood is particularly prone to dimensional instability. If wood is considered for the primary framing material, or even for components of the structure such as exposed wood beams or timber frame trusses, the shrinkage of the wood and the associated cost of the special detailing required must be considered.
In addition, with the increased emphasis on energy conservation, the long-term effects of shrinkage on the building envelope and building energy and maintenance costs must also be considered.
Wyka found Hance Construction and started consulting with the team regarding his ideal situation and site plans. When the original owner moved and sold, the building stood empty for over 20 years.
After reviewing options, comparing costs, and understanding structural space requirements and functionality needs, the Hance team came to Wyka with a plan to renovate the current structure and expand on the facility to accommodate additional needs. The team explained the cost benefits and durability assurances of steel and how renovation of this space provided customization options. By choosing a Butler structure, Wyka knew he could avoid major deterioration issues and save on renovation costs.
Butler Buildings are touted for their strength in engineering so even though the building sat vacant, the integrity of the structure was never in question. These structural systems are designed for strength, durability, longevity and sustainability. Wyka hired Hance Construction to renovate the vacant building into a mix-use office and warehouse facility and construct a 10,square foot addition. Hance not only executed the renovation and addition, they consulted Mile Square Roofing on cost saving opportunities and vendor partnerships.
Known for a holistic approach to project management, Hance connected Miles Square Roofing with an architect and financial consultant. The building came out beautiful. How long do steel buildings last?
Steel buildings face fewer issues with deterioration and corrosion than concrete or wood, and can out live other structures when properly built and maintained. Most steel buildings last anywhere from 50 to years.
Why is steel a good building material? Galvanized steel intended for prolonged outdoor use should be hot-dipped galvanized steel; which commonly lasts for about 70 years in many different environments. Table 1 below predicts how long galvanized steel will last based on a 30 month corrosion study of environmental factors like wetness, humidity, and air pollutants in The corrosion resistance of zinc coatings is determined primarily by the type and thickness of the coating but, varies with the severity of environmental conditions exposed to as in the table above.
Hot dipped galvanized zinc coating resistance to corrosion depends primarily on a protective film patina formed on its surface. Read more background:. The type of zinc galvanization and how that process controls the way in which the galvanized steel corrodes must be understood first. The environments, elements, and conditions that any given type of galvanized steel is exposed to, nevertheless, indeed determines how long it will last before corrosion. A study of galvanized steel corrosion in industrial, rural and sea regions found:.
The handy chart below from American Galvanizers Association illustrates how long galvanized steel will last before corroded areas should be maintained to prevent further deterioration. Want to learn how to refinish galvanized steel? Click here. Put another way, this chart shows how long it takes for galvanized steel to rust in different environments. The thicker the zinc coating the longer galvanized steel will last without corrosion.
The thickness of zinc is displayed along the horizontal axis 8. As in the chart below and noted in the study, for each location the corrosion rate is essentially constant with time 9.
Chart 1: Time to first sign of corrosion in various environments. The environments below are listed from the most corrosive to the least corrosive: Industrial Environments:.
The presence of SO2 in the atmosphere largely regulates the atmospheric corrosion rate of zinc. When acids - with a pH below seven - attack and corrode a galvanized zinc coating, the pH decreases and the rate of corrosion increases. In industrial locations mists and dews have been observed having a pH as low as three. It is rational, therefore, to attribute the greater corrosivity of industrial atmospheres to the acid-forming SO2 pollution contained within them 9.
Results of a galvanized zinc metal corrosion potential study published in found the highest corrosion impact from SO2, dust, humidity and CO2.
Concentrations of these pollutants were highest values in winter; when fossil fuel combustion increases. The presence of chlorides in air during also influenced the rate of corrosion Soil Just as the acidity of the atmosphere influences the rate of corrosion, so too does the acidity of the soil.
The zinc coating of hot-dipped galvanized steel will last in the harshest soil is 35 to 50 years and in less corrosive soil 75 years or more. Temperature Although humidity affects corrosion, temperature itself has less of an impact. Galvanized zinc coatings respond well in extreme cold and hot temperatures.
There are no significant differences in corrosion rate in temperatures below F for hot-dip galvanized coatings. In higher temperatures the zinc can be impacted. For long-term continuous exposure the maximum recommended temperature is F, according to a publication by American Galvanizers 8.
Temperatures this high can cause the outer zinc layer to peel away from the zinc-alloy layers.
0コメント