Degree Lecture Notes - Building construction 2 (part 2) by Sheilly Tan

W3-SKELETAL CONSTRUCTIONPART 1

NORITA JOHAR

INTRODUCTION In ancient times, building are commonly constructed with masonry and bricks. Walls are thick and heavily butressed. Thus, the buildings cannot be built too high. Things changes as steel and skeletal construction are discovered. Buildings can be built faster and higher to accommodate more users on limited land. What is skeletal construction?

SKELETAL CONSTRUCTION

DEFINITION A frame is a structure used to resist vertical forces (gravity, rain, dead and live load) and lateral forces ( wind & earthquakes).

FRAMING SYSTEM A buildingâ&#x20AC;&#x2122;s framing works in conjunction with its foundation to provide strength and stability for the structure; it is also another critical component of the load path. Framing must transfer all load gravity, uplift, and lateral loads to the foundation.

LOAD TRANSFER roof

beams

It transfers load from structural elements to foundation then to ground.

columns

ground slab foundation

THE COMPONENTS @ girder

Roof slabs

Floor slabs

Ground floor slabs

COLUMNS A column (pillar / post) is a vertical member carrying the beam and floor loadings to the foundation, and is a compression member.

BEAMS Beams transfer their loadings to the columns. Beams can vary in their complexity of design and reinforcement.

BEAMS There are many types of beams, namely:

CONNECTIONS The integrity of the overall building depends not only upon the strength of these components, but also on the adequacy of the connections that exist between them.

STRENGTH

CONNECTIONS

CONNECTIONS The most critical connections: •roof system to supporting walls •openings and headers in the walls •walls to floor levels •walls to foundation

TYPES OF FRAME JOINTS

1)RIGID/ FIXED ENDED

3)BRACED

2)PIN ENDED

4)PORTAL

1) RIGID FRAME Rigid frame is a structure made of linear elements, typically beams and columns that are connected with joints that do not allow rotations. Structures are built at the site which may or may not be poured monolithically. When concrete column and beams are cast in one piece or when steel members are welded together, it is also called rigid.

Rigid frame structures provide more stability. Rigid frame structures resist rotations more effectively. However, when rigid frame is forced to move by earth quake, there is no flexibility since all members are firmly connected between one another. The beam or the column or connections may break.

2) PIN ENDED FRAME

3) BRACED FRAME Braced frame structures resist lateral forces by the bracing action of diagonal members. Braced frame structures are used to resist sideway forces. Buildings are braced by inserting diagonal structural members into the rectangular areas of a structural frame. Advantages â&#x20AC;˘ To stabilize the frame against earthquakes and strong winds. â&#x20AC;˘ Lateral forces are resisted by axial actions of bracing and columns. â&#x20AC;˘ More efficient than a rigid frame.

Non braced frame is not sufficient for high rise buildings

3) BRACED FRAME

External bracing Not only for structural use, but it also offers aesthetics to the building

3) BRACED FRAME Internal bracing May be concealed or left exposed

3) BRACED FRAME Bracing on roof Larger bracing may eliminate the use of purlins

4) PORTAL FRAME A portal frame these can be defined as two dimensional rigid frames which have the basic characteristic of a rigid joint between the column and the beam allowing the frame to act as one structural unit.

4) PORTAL FRAME Generally portal frames are used for single-story buildings or low-rise buildings. There are 3 types of portal frame, fixed, 2 point and 3 point frame.

4) PORTAL FRAME

TYPES OF FRAME BY MATERIALS

Steel

Timber

Concrete

Steel Framing Advantages Flexible & Easy to Install Higher quality / tolerances Dimensionally stable Lighter, Stronger Price Stability Insect resistant Non-combustible Less waste, Recyclable

Steel Framing - Disadvantages Corrode if exposed to water Previously - not code approved Protection of electrical wiring Isolation of dissimilar materials Thermal transmission â&#x20AC;&#x153;Installedâ&#x20AC;? Cost of Steel vs. Wood

steel above ground

concrete below ground

THE COMPONENTS COLUMN PLATE/ ANGLES/ WELD MAIN BEAM / GIRDER

JOIST

CONCRETE SLAB STEEL DECK

FLOOR JOIST

OPEN WEB STEEL JOIST A mass-produced steel truss used in closely spaced arrays to support floors and roof decks

Deck is served as reinforcement. At the floor beam, metal shear studs must be inserted to add composite action between slab and beam. Tile or other flooring can be added on top.

STEEL SHAPES

CONNECTIONS

force

Moment reaction

HOW? CONNECTIONS

distance

moment

COLUMN TO BEAM-moment

SHEAR Shearing forces are unaligned forces pushing one part of a body in one direction. If the reaction is not equal, it may cause sliding.

COLUMN TO BEAM-shear SHEAR CONNECTIONS Bolts only in web, not the flanges Transmits only shear Not bending moment Accomplished with clip angles & bolts/welds

COLUMN TO COLUMN

Joining Steel Members Rivet

Bolt

Weld

Rivets Installation Process •Heat Rivet •Insert in Hole •“Hammer” to produce a second head •Cool - Expands to form a tight joint

Seldom Used any more •Labor Intensive •Less Expensive Alternatives

Welding Welding vs Bolting (Both can achieve similar performance) •Welding

labor intensive (especially in the field) Requires a highly skilled/certified craftsman Verification of Installed Quality - inspection, X-ray, etc •Bolting - Quick, easy, and less labor intensive & skill req’d •Not uncommon to see both

Welded fabrications in the shop Bolted in the field

Full Penetration Weld

Fillet Weld

FIREPROOFING OF STEEL Fireproofing of steel framed structures:

Building fires are not hot enough to melt steel, but are able to weaken it sufficiently to cause structural failure. For this reason, building codes limit the use of exposed steel framing to one to three stories, where quick escape from fire is possible; in addition collapse of the building is unlikely to endanger people or other buildings â&#x20AC;&#x201C; For taller buildings it is necessary to protect the steel frame from heat for a length of time sufficient for the people to be evacuated and the fire to be extinguished. Fireproofing of steel framing done is different ways -

Fire protection of beams: - Encased in reinforced concrete - Enclosure in metal lath and plaster - Rigid slab fire proofing - Spray on fire-proofing - Suspended ceiling

Fire protection of columns: - Encased in reinforced concrete - Enclosed in metal lath & plaster - Enclosed in multiple layers of gypsum boards - Sprayed on fire-proofing - Loose insulating fill inside an enclosure - Water filled box column

• Encasement with a fire resistant material – Concrete or Masonry • Adds dead weight

– Plaster • Costly/labor intensive • Exterior or humid applications

– Drywall • Also serves as finish material

– Spray-on Fireproofing – Combination – Paints

Spray-on Fireproofing Mixture Cementitious fiber & binder mixture Sprayed to the required thickness Greater thickness = greater Resistance

Note the thickness is greater on the columns

Now that you know structure in steel building and how it is constructed……

Let us start designing the tower…..

2) TIMBER FRAMES Timber frames can be used to construct a smaller project and not suitable for tall / high rise buildings.

Properties Advantages: • Recyclable • Sustainable Disadvantages: • Susceptibility to decay when exposed to excessive moisture • Combustibility • Termites

Timber above ground

concrete below ground

THE COMPONENTS TOP PLATE

BOTTOM PLATE

THE COMPONENTS

TIMBER FRAMING TYPES • Balloon • Platform

Platform frame

BASIC TIMBER JOINTS

Tongue & groove T halving

Notch

Nail less buildingâ&#x20AC;ŚIstana Seri Menanti

So, next weekâ&#x20AC;¦..we will learn about concrete frame. Any questions?

Thank you

Week 4-SKELETAL CONSTRUCTION - PART 2

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3) CONCRETE FRAME

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MIXING CONCRETE CONCRETE RATIO 1:2:4 – 1 part cement, – 2 parts fine aggregate – 4 parts coarse aggregate

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CONNECTIONS

rebar stirrup

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REINFORCEMENT

Steel bar is used for reinforcement because steel has tensile strength where as concrete has compressive strength

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REINFORCEMENT

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REINFORCEMENT

compression

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REINFORCEMENT

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FORMWORK

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POURING CONCRETE

Manual

Pump & vibrator

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POURING CONCRETE

Improper vibrating may cause honeycombs, that affects the durability of concrete. Honeycombs are hollow spaces and cavities left in concrete mass on surface or inside the concrete mass where concrete could not reach. These look like honey bees nest. Ar. TH Chin

CURING CONCRETE

Curing concrete is the term used for stopping freshly poured concrete from drying out too quickly. This is done because concrete, if left to dry out of its own accord, will not develop the full bond between all of its ingredients. It will be weaker and tend to crack more. Ar. TH Chin

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PREFABRICATION Concrete construction is time consuming. There are many steps that need to be done as explained previously. Nowadays, concrete structural elements may be created at the site. PREFABRICATION is the element of building which is manufactured in factory and then transported to the site. All the processes involved in concrete construction are done at the factory. This speeds up construction period and thus, saves cost.

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BASE TO COLUMNS The column will be inserted into the starter bar on the footings. Structural grout will be poured in between the bars to form a strong bonding between the bar and the column.

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COLUMNS

Corbelfor the beams to rest on

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COLUMN ON COLUMN CONNECTION

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COLUMNS TO COLUMNS

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BEAMS

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BEAMS

1) Rubber base 2) Connection- bolted or using angle Ar. TH Chin

Bearing pads on corbels

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SLABS Ar. TH Chin

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SLABS

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WALL PANEL

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Now we have learnt the skeletal frame by different materials, steel, timber and concrete. We will examine other components of skeletal frame: • TRUSS • SKIN OF THE FRAME

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TRUSS

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APPLICATION OF TRUSS • Bridge ( Long span truss )

• Roof ( short to medium span truss ) – Flat – Pitch – Organic shaped

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LONG SPAN TRUSS

Made up of triangulated members. Can be used in heavy engineering projects such as bridges and railway station.

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LONG SPAN TRUSS

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SPACE FRAME A structural roofing system based on a simple repetitive pyramidal unit to give large clear spans of up to 22m for single spanning designs and up to 33m for two way spanning designs. The steel units are easily transported to site before assembly into beams and the complete space deck at ground level before being hoisted into position on top of the perimeter supports.

2 way

3 way

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Space frame Roof structure

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RAFTERS-SHORT SPAN A two or three dimensional framework where each member is either in tension or compression. Often used in roof construction for small span, as well as large span.

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Timber Pitched Roofs up to 7.5 m Span

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Steel Roof Trusses-up to 12m span These are triangulated plane frames. Steel is stronger than timber and will not spread fire over its surface and for these reasons it is often preferred to timber for medium and long span roofs. The rafters are restrained from spreading by being connected securely at their feet by a tie member.

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TYPES OF PITCH ROOF

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TYPES OF PITCH ROOF & parts of a roof

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NO RIDGE ROOF FRAME

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STRUTS & TIES Struts and ties are provided within the basic triangle to give adequate bracing.

Angle sections are usually employed for steel truss members since they are economic and accept both tensile and compressive stresses. The members of a steel roof truss are connected together with bolts or by welding to shaped plates called gussets.

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CONNECTIONS-GUSSET PLATE

Riveted

Bolted

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CONNECTIONS-GUSSET PLATE

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FRAME & SKIN The shell of a house serves as the first line of defense between the occupants and the outdoor environment. Walls function as a weather barrier, nail base for finish materials and an energy conserving boundary. A sensible wall system is durable. And this requires all components in a wall assembly to be compatible for the long haul. Siding, siding finishes, housewraps, insulation and wall frames must work together while achieving distinctive goals.

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FRAME & SKIN Frame is the structure which can be exposed and infill with materials in between or can be sealed with cladding.

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IN FILL SYSTEM Frame can be in filled with suitable materials. The selected materials will be laid in between the frame. It has no load bearing properties.

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CLADDING SYSTEM The lightweight outer skin of a building that does not carry any weight or support the building, but does keep wind and rain out. A term used to describe the materials covering the exterior of a building.

There are many materials to be chosen to beautify existing frame structure such as timber, masonry, gypsum board etc. Ar. TH Chin

METAL CLADDING

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METAL CLADDING

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Brick Veneer Brick veneer enhance the appearance of a building and improves the performance of walls.

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Brick Veneer

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CURTAIN WALL With skeleton-frame construction, exterior walls need carry no load other than their own weight, and therefore their principal function is to keep wind and weather out of the buildingâ&#x20AC;&#x201D;hence the name curtain wall.

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CURTAIN WALL- MULLION

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CURTAIN WALL- MULLION

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CURTAIN WALL- ANCHOR

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CURTAIN WALL- SPIDER Curtain wall using spider connector.

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SOLID STRUCTURE

WHAT IS SOLID STRUCTURE ? • Can be made by, piling up or forming similar materials into a particular shape or design. • An object that uses solid construction to support loads •Held in place by its own weight, losing small parts often has little effect on the overall strength of the structure

CLASSIFICATION

NATURAL

not made by people - occur naturally in the environment

MAN-MADE

built by people - many are modelled after natural structures

NATURAL

MAN-MADE

THE HISTORY AND DEVELOPMENT OF LOAD BEARING MASONRY BUILDINGS Load bearing construction has a very long, bright and interesting history.

To start with, masonry structures were large and solid, like the pyramids.

Polygonal masonry

Volcanic (Lava) stone

Yellow Limestone Bricks - -ancient Egypt

Roman Masonry Stone

A well-made solid structure can last for a very long time

In India, builders started using horizontal slabs of stone to construct floor plates. This is called trabeate construction. The Taj is built of red sandstone masonry walls faced with white marble. Its walls are 6ft (1.8m) thick in some places.

With the development of the arch, openings were created in these structures, and large structures like the colosseum in Rome were built. The arch was first developed in Mesopotamia (modern-day Iran-Iraq-Turkey-Syria) and was then picked up by the Romans.

ARCH ď&#x201A;§ It is considered as a superior form of construction structure than the post and lintel. ď&#x201A;§ The arch requires more planning and materials to create, but it distributes the weight out and downward giving less stress on to the material itself. Therefore it doesn't depend on the strength of the material and is stronger than post and lintel. ď&#x201A;§ The arch has a key tone set on the upper center position and is the most important part of the structure because it holds up all the stones which compose the arch.

Voussoirs are wedged-shaped units, usually made from stone, that are used when building an arch. There are also two distinctive types of stones: keystones and springers. A keystone is a center stone that is placed within the apex of an arch. This stone tends to be larger than all the rest, and it is usually elaborately decorated. The

purpose of a keystone is to lock all the other stones into their proper positions. Springer stones are the lowest stones in an archway. These stones are often placed on either side of the arch towards the bottom of the arch itself. Since these stones support an entire arch, they are vital to any sound arch construction. Both the keystone and the springer are considered voussoirs.

Rib vault are the same as groin vaults in structure but have more decorations. These decorative elements differentiate groin and ribbed vaults

Fan vault A rib vault in which slender curving ribs radiate u pward from the top of a column like the ribs of a fan to form inverted half cones.

ISLAMIC ARCHITECTURE What today is known as Islamic architecture was influenced by ancient structures that already existed in Roman, Byzantine and Persian lands which the Muslims conquered in the 7th and 8th centuries

POST AND LINTEL (cont’d)  The post and lintel was the simplest way to keep a roof over a person's head in ancients times what looks like a giant doorway is composed by 2 vertical posts which are capped up by a horizontal lintel  The sustainability of the post and lintel depend on the weight of these war materials, due to the fact that the stress of the weight of the materials pushes directly downward keeping the horizontal pieces in constant stress.

A pilaster is a rectangular support that resembles a flat column. The pilaster projects only slightly from the wall, and has a base, a shaft, and a capital

Pilaster constructed together with walls

http://www.imiweb.org/design_tools/masonry_details/details/02.010.1101.php

WHAT IS WALL?  An upright structure of masonry, wood, plaster, or other building material serving to enclose, divide, or protect an area, especially a vertical construction forming an inner partition or exterior siding of a building  A continuous structure of masonry or other material forming a rampart and built for defensive purposes

 A structure of stonework, cement, or other material built to retain a flow of water

Wall System  Vertical planes of a building which define and enclose its interior spaces  They may be bearing walls of homogeneous or composite construction, or they may be constructed of linear columns and beams with non-structural panels filling in between them

Building Construction Illustrated – Second Edition Francis DK Ching

 Exterior walls serve as a protective shield against weather for a building’s interior spaces. It must be durable and resistant to the weathering effects of sun, wind and rain  The interior walls which subdivide the space within a building may be either non-structural or loadbearing. Their construction should be able to support the desired finish materials, provide the required degree of acoustical separation, and accommodate when necessary runs of mechanical and electrical lines Building Construction Illustrated – Second Edition Francis DK Ching

 The size and location for door and window openings in walls are determined by the requirements of natural light, ventilation, view and physical access. They must be constructed so that any vertical loads are distributed around the openings and not transferred to the door and window units  In a load bearing structure, you cannot simply punch holes in a wall to connect two rooms - you would damage the structure if you did so. The immense weight of the walls actually helps to hold the building together and stabilize it against external forces such as wind and earthquake. Building Construction Illustrated – Second Edition Francis DK Ching

Buildings in the early architecture were built using solid materials, mainly from stones. Load bearing masonry construction was the most widely used form of construction for large buildings from the 1700s to the mid-1900s. Europeans built fine stone walled buildings with floor slabs made of wood beams and planks. The buildings had elaborate arched openings and very finely crafted domes. These buildings have lasted hundreds of years, with limited repair in many cases, testifying to the quality of the craftsmanship and the brilliance of the design.

And then, the Americans came in and super sized things. At left is the Mondadnock Tower, a 16-storey office building built in 1893 in Chicago. It was made of brick walls 6 feet thick at the base and about 18" thick at the top. It still exists.

It was built to be the world's largest office building at the time by architects Burnham & Root. They said their design was inspired by an Egyptian pylon, which is a kind of monumental gateway to a temple, built with massive sloping masonry walls.

Factors in Wall Design & Construction Strength  in supporting vertical loads from floor, wall and roof structures above  Resisting lateral wind and seismic forces and lateral loads from supported floor and roof structures

Building Construction Illustrated – Second Edition Francis DK Ching

Factors in Wall Design & Construction Connection to foundation, floor and roof systems  Floor and roof systems may bear on the wall system so that their edges are exposed and cantilevers are made possible  Floor and roof system which is continuous for the height of the building

Building Construction Illustrated – Second Edition Francis DK Ching

Factors in Wall Design & Construction Wall finish desired  Compatibility between base material of wall and desired wall finish  Visual characteristics of color, texture, pattern and jointing

Building Construction Illustrated – Second Edition Francis DK Ching

Factors in Wall Design & Construction Door and Window Openings  Structural and/ or modular limitations on size, proportion and location  Effect on daylighting and potential for heat loss or gain

Building Construction Illustrated – Second Edition Francis DK Ching

Factors in Wall Design & Construction Weathertightness and the control of :  Heat flow  Air infiltration  Moisture and water vapour  Sound transmission Expansion and Contraction  Type and location of expansion joints, if required Building Construction Illustrated – Second Edition Francis DK Ching

Factors in Wall Design & Construction Accommodation of mechanical and electrical services and outlets

Fire resistance rating desired or required by the building code (ie UBBL) Building Construction Illustrated â&#x20AC;&#x201C; Second Edition Francis DK Ching

Materials for Walls Bricks ď&#x201A;§ Made of clay - Fired bricks - Non-fired bricks ď&#x201A;§ Made of concrete

Clay Brick Process

There are also hollow and grouted.

Solid Wall

Cavity Wall