Structural BIM – Know-How of Pre-Engineered Steel Buildings

In this fast-moving and the technology-driven world it is not simply fast-food that is processed and kept but even fabrics, construction components and designs that are pre-developed or engineered before time to assemble the final product within less time and with more ease. Talk about renovating a building or developing it from its initial brick prefabricated and pre-engineered components are the new mode of transformation in the construction industry.

Under Structural BIM services, there is now the development of Pre-Engineered Steel Buildings (PESB) which is the new trend in the market. PESB is factory-made buildings of steel that are shipped to the site and bolted together. These differ from other buildings since these can even be designed by a contractor under the practice known as design & build. Not just this, these pre-engineered buildings are cheap, fast to erect and can be easily dismantled and shifted to another site as and when needed. These structures are at times referred to as ‘tin sheds’ or ‘metal boxes’ and they are usually rectangular boxes surrounded in a skin of folded metal sheets. With such a mechanism the entire process is speeded because while the floor slab and foundations are being developed, the columns and beams of the structural system are being fabricated in the factory. So once the floor and foundations are made, the columns and beams are brought to the site, lifted by cranes, and bolted together.

Structural Systems of Pre-Engineered Building

It is the structural system of the PEB that gives the flexibility and speed to it. This entire system has factory-painted and factory-fabricated steel beams and column segments which are simply to be bolted together at the site. The beams and columns are first custom-fabricated as I-section members which will have an end plate consisting of holes for bolting at both the ends. These are created by cutting steel plates with the needed thickness and then welding them to make I-sections. The welding and cutting are done by industrial robots that bring about the desired speed and precision. For this, the operators must just input the CAD drawing of the beams into the machines which do the rest of the task. This production-line mechanism brings about great consistency and speed in fabrication. For maximum structural efficiency, the beams can be shaped tailor-made, where the forces are greater, they become deeper while shallow if the force is not that great.

Some of the crucial components of Pre-Engineered Steel Building are:

Primary Components
Secondary Components
Sheeting / Cladding
Accessories

Primary Components: This consists of mainframe, columns, and rafters.

Main Frame: This part mostly includes the rigid steel frames of the building. PESB rigid frame comprises tapered rafters and tapered columns, the tapered sections which are fabricated are known as built-up members. Flanges are connected to webs employing a continuous fillet weld on one side while the splice plates are welded to the ends of the tapered sections.

Columns: Transfer of vertical loads to the foundations is the main purpose of columns. PESB columns are made up of I-sections that are the most economical compared to others. From bottom to top of the column the width and breath would go on increasing. Flanges and webs that are made by welding from plates are a part of I-section.

Rafter: among the series of sloped structural members – beams, that extend from the ridge or up till the wall-plate, down slope perimeter and have been designed to provide support to the roof deck and all of its linked loads.

Secondary Components: The secondary structural components which are used as support to roof panels and walls are Grits, Purlins, Bracings and Eave Struts.

Purlins & Grits: Grits are used on the walls, purlins on the roof and eave struts at the intersection of the roof and the sidewall. Purlins and grits should be cold formed ‘Z’ sections with stiffened flanges.
Eave Struts: These are unequal flange cold-formed ‘C’ sections. Eave struts are usually 200 mm deep having 104 mm wide top flange and 118 m wide bottom flange which are both made parallel to the roof slope. Each flange has a stiffener lip of 24 mm.
Bracings: The primary member ensuring the stability of the building against forces in the longitudinal direction from the wind, earthquakes and cranes is a cable bracing. For the roof and sidewall, diagonal bracings need to be used.

Sheeting / Cladding: Sheets used for constructing pre-engineered buildings are made up of the following – Base metal of either aluminum conforming to ASTM B 209M or Galvalume coated steel conforming to ASTM A 792 M grade 345B. By weight, Galvalume coating is 45% Zinc and 55% aluminum. The exterior surface coating on the painted sheets is of 25 microns of epoxy-primer having a durable polyester finish, while the interior surface coating of painted sheets is of 12 microns of epoxy primer along with modified foam or polyester. The sheeting material is cold-rolled steel having high tensile yield stress of 550 MPA along with hot dip metallic coating of Galvalume sheet.

Accessories: This comprises the non-structural parts of the building namely sliding door, insulation, turbo ventilator, window, roll up shutter, ridge ventilator, roof skylight, ladder with safety cage and adjustable Louvre make up for the accessories of the PESB.

Advantages of using a Pre-Engineered Steel Building through BIM services:

Control over Quality: Since the buildings are now pre-manufactured or fabricated in the factory the quality is maintained and assured due to having control over the conditions and ways of manufacturing.
Lower Maintenance: For suiting the ambient conditions of the site, the buildings are mostly supplied with good and premium quality paint systems for cladding and steel, which naturally brings about long durability and reduces the maintenance costs.
Construction Time Deducted: In India, the use of pre-engineered buildings will reduce the overall construction time by at least 50% which will mean faster occupancy and fast realization of revenue. This is typical because the buildings will be delivered within a few weeks of getting approvals for drawings. The anchor bolts and foundation are cast in-line with finished which is ready for bolting on the site.
Expansion Flexibility: Due to pre-designing and pre-engineered mechanism buildings can be easily expanded by adding further bays for length and similarly expansion in the height and width can be done.
Cost Reduction: Having the systems approach one can immensely save costs in the design, manufacturing, and on-site erection. The transportation cost is reduced due to the secondary members and cladding nest.

While these are just a few benefits of using PESB, the steel buildings strength and large clear spans imply that the design is not simply restricted to the need for having an intermediate support wall and can be reused, modified and relocated as and when the requirements change through the years. These pre-engineered steel buildings under Structural BIM Services hold a unique and special place in the construction industry for it being suited to the needs of the modern engineering industry. These PESB would be the only options for huge industrial areas that have acoustical and thermal characteristics in recent times.

ASC Technology Solutions is one of the leading BIM Services Provider in India. ASC outsources bim services to clients, contractors, architects, and construction companies across USA, U.K, Europe, and Australia.