Q: Where do you see this unique industry going in the next 5 years?
A: Over the next five years the industry will be driven by the market for lower-cost residential, commercial and industrial construction. Accordingly, where C-purlins (the primary section used for the on-site fabrication of I and H-section columns, piles and beams) now ranges between 1.2 and 1.5mm in thickness, the industry will move to increase the thickness up to possibly 2.5mm and greater. In addition to C and Z- purlins, purlin manufacturers will add more geometric shapes to their line in order to improve area-inertia properties.
As these improvements take place, the structural load bearing capacity of these members should increase, thereby allowing the industry to replace more costly traditional sections with lower cost LW sections. The overall effect should drive down the cost of construction and cause construction projects previously deemed uneconomic to be ventured as an economically viable.
For example: An I-beam fabricated on-site without welding using 2.5mm thick steel C-purlins will then have second moment of inertia equal to that of a comparable heavy steel section and will have a weight savings of close to 200%.
The effect of these endeavors will hopefully give rise to expansion of the industry over the next five years.
Q: What techniques are engineers using to design these LWT sections?
A: Immediately, the research capabilities of SkyCiv come into focus, whereby the engineer can maneuver the geometry and axis orientation of a single purlin with respect to another and investigate the resulting effects of these changes. Thus, in designing a single I-section from the combination of 2 similar or dissimilar C-purlins, or a truss section from the combination of a number of C-purlins, the engineer can study the effects of changing LW section specifications and environmental conditions (wind, rain, snow, earthquake etc.) on moment of area, load bearing, deflection and bending moment.
The SkyCiv platform reports generated from these analyses will eventually direct on-site fabrication for customizing the LW section members. The final step of this series of calculations from the SkyCiv platform is to optimize the weight versus the structural integrity of each section member, thereby minimizing the cost of construction through the reduction in $/lb. of steel utilized in the construction process.
Q: Are the LW components made with any special materials? Are these materials readily available?
A: The good news is that these LW components are not made with any special materials. Standard hot dipped galvanized low carbon steel sheets varying in thickness between 1.2 to 1.5mm are formed into LW components utilizing the cold forming process in most cases . These forming processes are well established and codes for standardized bolt and screw connections are well documented in the structural engineering literature.
Low carbon steel is currently readily available in all countries who themselves purchase from the world's major steel suppliers (US, Brazil, India and China).
Two-story luxury oceanfront under construction using 100% LWT; Unique pile/column/floor beam connections shown on right
What are the pros and cons of LWT?
Q: Other than reduction in weight, what are some of the positives of the LWT innovation?
Most of the positives of this innovation are enveloped in the main theme of Light Weight Technology. However, some major indirect advantages include:
- Transportation and handling logistics of these construction materials are greatly reduced and can be handled by manual labor instead of heavy machinery.
- The increased cost savings resulting from utilizing this innovation has resulted in previously uneconomic construction projects being restarted as economically viable employment generators especially at the low to unskilled labor level.
- A notable spin-off from this is that the potential for employment of labor is enhanced especially in depressed economies where there is a great supply of low to unskilled labor. This can have a formidable impact on easing the increasing unemployment statistics in the construction industry in a post- COVID era where the IMF in its latest report on Latin America and the Caribbean have stated that for these regions of the world real income and employment will decrease until 2025, more than any other region. Post 2025, employment will increase marginally unless there are vigorous efforts by world leaders to prevent this. Structural Engineering by way of LWT is therefore an obvious contributor.
- This LWT innovation has already started to cause an increase in home and agricultural DIY projects. Additions, replacements and repairs are on the increase with a corresponding increase in demand for the light weight structural members.
- Where safety is always the major concern on any construction site, accidents involving lost time, injuries and even fatalities will decrease as the use of lighter weight construction materials increase. In fact, OSHA statistics indicate that 20% of all worker deaths are in the construction industry and of that figure 28% is caused by: i) being struck by or pinned beneath heavy steel and ii) being squeezed by or between heavy steel. LWT can play its part in reducing these figures.
Q: Are there any drawbacks to these light weight sections?
- The first limitation is the current ability to undergo large scale construction involving large live and dead loads. For example high rise structures in excess of 5-stories, industrial vessel construction and long span bridges are obvious limitations.
- Currently codes for the use of LWT are either limited or unavailable in the wider structural engineering literature as its use has not been well or fully established. With time and continued use the industry will develop such.
- Software packages for its use have not been yet developed as the technology is driven by custom designs for specific projects. The analysis of the structural integrity of beam members for custom geometries requires engineering first principles which are now accomplished by the very tedious mathematical models for each section member which is usually non-standard. Computer packages to assist in the design are therefore lagging the use of the technology.
Hillside Cottage Utilizing LWT; Gable Roof Truss Design on left