PORTAL FRAME CONSTRUCTION & PRE ENGINEERED BUILDING SYSTEM

Prepared by Adrian Rollo ToisaArchitect/Instructor

• Describe the components of pre-engineered buildings.

• Identify the primary and secondary structural framing systems.

• Apply the wall materials, insulation, and installation of roofing, gutter, trim and accessories in architectural design.

Fig. Pre-engineered Building courtesy of SEA CON LLC

INTENDED LEARNING OUTCOME (ILO)

Background• Steel was very expensive item in construction.• Early 1900’s, the concept of metal building

originated in U.S.• Simple industrial structures using truss rafters,

straight columns, sectional roof & wall. Wedge pins for connections.

• Mass production of housing and storage modules for U.S. army during ww2.

• Metal building system recognized as a favorable method of construction over conventional methods.

• Late 1950’s and early 1960’s, computerized design allowed buildings to be tailored to individual cut.

Background• Roll forming lines allowed continuous span cold

rolled z-purlins.• Color coated panels and factory insulated panels

improved architectural appearance.• Major increase in design possibilities

contributed to the boom in metal buildings.• The term “pre-engineered building” came into

existence.• 1990’s – present, pre-engineered buildings

dominate the low rise building market.

Definition: Portal Frame

Fig. Our Lady of Fatima, Filigree of propped portal frames support the floating ceiling.by Keith Cottier

• A construction method of building and designing structures, primarily using steel or steel-reinforced precast concrete.

• Can also be constructed using laminated lumber such as glulam.

• The connections between the columns and rafters are designed to be moment-resistant to carry bending forces.

• First developed in the 1960’s and now become the most common enclosure for spans of 20-60m.

• Designed for the following loads: roof load and wind load. While designing care should be taken for proper: Joints, foundation and bracing.

Portal frames are made in a variety of shapes and sizes. They are usually made from steel, but can also be made from concrete or timber. The portal structure is designed in such a way that it has no intermediate columns, as a result large open areas can easily be created within the structure. Portal Frames are generally used for single storey construction which require a large unobstructed floor space ie

FactoriesShopping CentresWarehouses

Internal view of a portal framed warehouse

At this stage the floor is not in place.

Note the clear unobstructed floor area available.

With single storey buildings natural lighting is gained by placing clear sheets in roof layout.

These sheets will run from eaves to ridge at suitable intervals.

Base joint for Portal Frame

The legs or stanchions of the portal frame need connecting at the bottom to a foundation.

Here we can see the base joint connection in place.

Ridge joint for Portal Frame

Shown here is a ridge joint or apex joint.

It is Important that this joint is strong hence the use of wedge shaped pieces called gusset pieces to strengthen and increase the bolt area.

Knee joint for Portal Frame

• Gusset pieces will be used to increase strength, give greater bolt area and prevent deflection under load.

• Again the knee joint must be strong to support the roof loads and prevent bending.

Diagonal bracing for Portal Frame

With all types of frameworks we must think on stability ie movement. To help strengthen the framework and prevent movement diagonal bracing will be used.

Cladding rails for Portal Frame

• This slide shows the cladding rails for attaching the external metal cladding panels to.

• These rails can be fixed horizontal or vertical depending on the way the cladding panels are fixed.

Tie cables for Portal Frame

• These wire and tubular ties are used to prevent sagging of the cladding rails which can add considerable force unto the joints of the external cladding.

External wall detail• Here we see the finish of

the external cladding panels with the lower level facing brickwork.

• The blockwork behind creates a protective wall or firewall.

• Pre-engineered metal building (PEMB) system is a building enclosure system that always includes a structural system and often includes roof and wall cladding.

• The structural system consist of “rigid frames” that are fabricated from steel and ‘cold formed’ into an ‘I’ shape through a manufacturing process.

• Rigid frames consists of roof beams and columns that are field bolted together.

• The frames can span large distances without intermediate supporting columns.

• The frames are spaced at intervals between 15’ (4.5m) and 60’ (18m) and can span, column free up to 300’ (90m) across a building

Definition: Pre-engineered Building (PEB)

• Primary framing: Moment resisting frames with pinned or fixed bases.

• Secondary framing: Cold formed Z sections or C sections for purlins or girts designed as continuous beams spanning over rafters and columns with laps.

• Longitudinal stability: Wind load on building end walls is transferred through roof purlins to braced bays and carried to the foundations through diagonal bracing.

Definition: Pre-engineered Building (PEB)

Fig. Sample of PEB System, credits to http://www.shribalajiroofing.com/pre-engineering-building/

Pre-engineered Building (PEB) system features

• PEB System is computer assisted, design to create a building for specific use.

• The complete building system is Pre Engineered to facilitate easy production and assembly on site.

• Tailor made building based on the client’s requirements and actual design calculations using tapered sections.

• A combination of built-up section, hot rolled section, cold formed elements and profiled sheets.

• Designing and fabrication or casting is done in factory. Connected together in factories by welding.

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Pre-engineered Building (PEB) system features

• Building components are brought to site. Fixed or jointed at the site. All connections are bolted.

• Basically produced at the factory with high tensile steel material by collecting complete information of the shed or building (length, width, height, etc..)

• The entire design of all building components is based on international standards and involve high technical quality production.

Pre-engineered Building InsulationInsulation – The main purpose of insulating a building is to

reduce the heat transfer coming through the ceilings and openings. There are 2-kinds, the bulk and reflective insulation.

Bulk Insulation-Rock wool-glass wool-loose fill cellulose-polystyrene panels- polyester mattingReflective Insulation-Foil faced blankets-foil faced boards-Multi-cell foil products (2 or more layers of reflective foil)

Pre-engineered Building Insulation

Polyurethane insulation – A panel manufactured by a press injection method to produce a polyurethane core between exterior steel facings. Can be used on the wall and ceilings as cladding.

Fig. Sample of rolled polyurethane foam insulation

Fig. Sample of polyurethane foam

Pre-engineered Building Insulation

Fiber Glass Insulation – This can be used on the roof or wall and can be retrofitted on existing buildings. The fiber glass insulation is fire safe and CFC free and does not emit toxic smoke. It is laminated to the top and bottom steel facings with special chemical glue, hence, completely filling the insulation cavity.

Fig. Sample of fiberglass roof insulation

Pre-engineered Building Insulation

Sandwich Panel Insulation – Consist of two thinner metal sheets over a rigid core. Can be used on the roof or wall.

Fig. Sample of fiberglass roof insulation

Pre-engineered Building Insulation

Fig. Bubble wrap aluminum foil faced insulation

Fig. Rigid panel aluminum foil faced insulation

Pre-engineered Building Insulation• Uniformly textured inorganic glass fibers bonded together by

a non-water soluble and fire retardant thermosetting resin. It is free from coarse fibers and shot due to its mineral composition.

• PEBI is non-toxic and not hazardous to health.• As metal roof age they become more susceptible to corrosion,

normally beginning at the seams and spreading through out the panel.

Fig. PEBI

Applications

Fig. Aircraft Hangars Fig. Train Station

Fig. Car Showroom/ factory Fig. Warehouse

Applications

Fig. Office Building (on-going cons.)Fig. Indoor Stadium

Fig. School Fig. Highrise

Advantages• Aesthetic appeal• Faster completion• Economical• Seismic resistance• Ease of expansion• Maintenance free• Large clear spans• Controlled quality• Building can be closed in and

made water tight• Prefabrication are not affected

by weather• Site works such as drainage,

roads etc can be carried out until framework is ready for erection.

Disadvantages• Subject to corrosion• It has poor resistance to fire as it

bends easily when hot.

Fig. Truss & column and portal frame system

Fig. Conventional Section Fig. Pre Engineered Tappered Section

Fig. Pre Engineered Stepped Section

REFERENCES

https://en.wikipedia.org/wiki/Portal_frame

http://www.ediscompany.com/what-is-a-pre-engineered-building/

http://www.kirbyinternational.com/products-services/peb/insulated-sandwich-panels.html

Pre-Engineered Construction Analysis & Design of Portal Frame by N. Patel, & S. Sharma

ESDEP lecture note (WG14), lecture 14.6: Special Single Storey Structures

Pre Engineered Building System by H.K. Gulati, A. Srinivas Rao & M.R. Mirza

ZAMIL STEEL Pre-Engineered Buildings

THANK YOU CREATURES!~ART