|Feature||Pre-Engineered Steel Buildings||Conventional Steel Buildings|
|Design Criteria||AISC, MBMA, AWS||AISC, AWS, JIS, DIN, BS|
|Structural Base Material||All primary and secondary steel used by MBS has a minimum yield strength of 50 KSI (345 N/mm2).||In most cases the primary and secondary steel used has a minimum yield strength of 36 KSI (250 N/mm2).|
|Foundation||Simple design, easy to construct and lightweight||Extensive heavy foundations required.|
|Delivery||Average 6 to 8 weeks||Average 20 to 24 weeks|
|Sourcing & Coordination||Building is supplied complete with: cladding and all accessories, all supplied from a single source.||Many different sources of supply, with an additional time requirement for Project Management to coordinate suppliers and sub-contractors.|
About 30% lighter through the-efficient use of steel. Primary framing members are (varying depth) tapered built-up plate sections with large depths in the areas of highest stress.
Secondary members are light gage (lightweight) cold formed (low labor cost) “Z” – or “C” shaped members. Z purlins/girts can be lapped.
Lapping reduces the deflection, and allows double thickness at the points of higher stresses (support points).
Primary steel members are selected from standard hot rolled “I” sections, which in many cases are heavier than what is actually required by design (due to availability in the market)
Members have constant cross-sections along the entire span, regardless of local stress magnitude
Secondary members are selected from standard hot rolled ‘I” and “C” sections, which again are much heavier than required
Quick and efficient since standardization of PEB has significantly reduced design time.
Basic designs are used over and over. Specialized computer analysis and design programs reduce design time and optimize material required.
Drafting is also computerized with minimal manual drawings. Design, detail drawings and erection drawings are supplied free of charge by the manufacturer. Approval drawings may be prepared within 10 days to 3 weeks. Consultant in-house design and drafting time is significantly reduced, allowing more time for coordination and review, and increasing margins in design fees.
Since most PEBs are pin-based, the cost is reduced due to smaller sections at the base with smaller base plates and foundations (in absence of moments).
Each conventional steel structure is designed from scratch by the Consultant, with fewer design aids available to the Engineer. Maximum engineering required on every project.
Generalized computer analysis programs require extensive input and design alterations.
Drafting is manual or only partially automated.
Significant time and expense on consulting services are devoted to design and drafting, as well as coordination and review.
|Designed to fit the system, with standardized, interchangeable parts, including pre-designed flashing and trims. Mass produced for the economy. All available with the building.||Every project requires special design for accessories and special sourcing for each. Flashing and trims must be uniquely designed and fabricated.|
|Erection||Easy, fast and efficient. Erection costs and time are accurately forecast, based upon extensive experience with similar buildings.||Slow, extensive field labor required. Typically 20% more expensive than a normal PEB building. Difficult to accurately estimate erection costs and time.|
|Architecture||Outstanding architectural design at low cost. Conventional wall, and fascia materials, such a concrete, masonry, and wood, can be utilized.||Special architectural design requires research, more time and higher cost.|
|Overall Price||Price per square meter may be as much as 40% lower than conventional steel.||High price per square meter.|
Flexible, tailor made, changes and revisions made easily.
Future expansion is simple, easy and cost effective. One supplier to co-ordinate changes.
|Changes, revisions, and additions can be difficult due to extensive redesign and co-ordination among suppliers and subcontractors.|
|Performance||All components have been specified and designed specifically to act together as a system, for maximum efficiency, precise fit and performance in the specified field conditions. Continuous design improvements over time allow for dependable prediction of performance.||Components are designed in general for possible use in many alternative configurations. Design and detailing errors are possible in assembling diverse components into unique buildings. Each building design is unique, so prediction of how components will perform together is uncertain. Materials which have performed well in some climates may not in other environments.|
|Responsibility||Single source of supply results in total responsibility for one supplier, including design liability.||Questions of who is responsible arise when components do not fit properly, insufficient material supplied, or materials fail to perform, particularly at supplier interfaces. The consultant carries total design liability.|