Structural Systems

Name: Umaru Mohammed

Proff. Yassin Sallam

TABLE OF CONTENT INTRODUCTION ..................................................................................................................................................................... 5 STRUCTURAL SYSTEMS ....................................................................................................................................................... 5 FOUNDATION SYSTEMS .................................................................................................................................................. 6 SHALLOW FOUNDATION ............................................................................................................................................... 6 DEEP FOUNDATIONS ....................................................................................................................................................... 6 BEARING WALL SYSTEM ................................................................................................................................................ 7 APPLICATION .................................................................................................................................................................. 7 POST AND LINTEL ............................................................................................................................................................. 8 PRECAST BUILDING SYSTEM ........................................................................................................................................ 9 TENDENCIES IN PRECAST CONCRETE .................................................................................................................11 Advantages of Precast Concrete ...........................................................................................................................................11 Disadvantage of precast concrete .........................................................................................................................................11 CAST-IN-PLACE CONCRETE SYSTEM ........................................................................................................................11 CONCRETE......................................................................................................................................................................12 COMPOSITION OF CONCRETE.................................................................................................................................12 The advantages of concrete are; .......................................................................................................................................13 Its major disadvantages are;..............................................................................................................................................13 STEEL................................................................................................................................................................................13 The advantages of steel are ...............................................................................................................................................13 WOOD...............................................................................................................................................................................14 Major advantages of wood are: ........................................................................................................................................14 Major disadvantages are: ..................................................................................................................................................14 Composite of wood ................................................................................................................................................................15 BRICK ...............................................................................................................................................................................15 Kind of brick shapes ..........................................................................................................................................................16 Advantages of brick include ..............................................................................................................................................16 Disadvantages include.......................................................................................................................................................16

IRON..................................................................................................................................................................................18 The advantages of iron are ................................................................................................................................................18 Its disadvantages are ..........................................................................................................................................................18 STONE...............................................................................................................................................................................19 Types of stone ....................................................................................................................................................................19 GRANITE: ........................................................................................................................... Error! Bookmark not defined. LIMESTONE: ...................................................................................................................................................................20 MARBLE: ..........................................................................................................................................................................20 The advantages of stone are ..............................................................................................................................................21 Its disadvantages include ..................................................................................................................................................21 MOTAR ................................................................................................................................................................................22 SPACE STRUCTURAL SYSTEMS .......................................................................................................................................24 General Introduction ..................................................................................................................................................................24 FRAMING SYSTEM ........................................................................................................................................................24 

Interior partitions.......................................................................................................................................................25

Balloon framing: ....................................................................................................................................................................25 Platform framing: ..................................................................................................................................................................26 Truss Construction.................................................................................................................................................................26 Advantages of truss: ...........................................................................................................................................................26 Types of Trusses .................................................................................................................................................................27 Heavy Timber Truss Systems ............................................................................................................................................27 Characteristics ....................................................................................................................................................................27 Light Weight Wooded Truss Systems ..............................................................................................................................28 Metal Truss Systems ..........................................................................................................................................................28 Types of truss designs ........................................................................................................................................................29 ARCHES ...............................................................................................................................................................................32 Construction process .............................................................................................................................................................32 Types of arch ......................................................................................................................................................................32 Other types .........................................................................................................................................................................34 Stone arch in Yemen..............................................................................................................................................................34

VIERENDEEL GIRDERS ..............................................................................................................................................34 Characteristics ....................................................................................................................................................................35 Schematic forms of vierendeel girders and frames ...........................................................................................................36 Features of vierendeel girder at Yale University ..............................................................................................................36 REFERENCES ...................................................................................................................................................................39

INTRODUCTION Generally, structure is a necessary part of architecture; with reason being that it ensures the stability of buildings. In engineering design process, structural members should be design to enable the resolution and transfer of forces to the ground. This is achieved by various structural systems, depending on what kind of structure is to be built. Some of these structural systems include;

Foundation systems

STRUCTURAL SYSTEMS

Bearing wall systems Skeleton Structures systems Compound systems Folded Plates and shells system Tensile Structures Space structures Special Structure systems

FOUNDATION SYSTEMS Foundation design in the past has always been very much a matter of inspired guesswork on a background of past experiences. Ancient methods were pathetically crude. Winchester cathedral was built originally on a foundation of short Oak piles and bundles of wattles in a bed of peat. This has survived for 750 years due to the preservative qualities of the peat. It was until the spread of rational thought processes in France in the 18th century that led to the development by coulomb of his theory of earth pressure against retaining walls. The Montauk building (10 storeys) was the first to use a steel grillage foundation and the stock exchange building 1894 became the first to use large diameter concrete piles. Except in few cases where a level bed of rock is sufficient foundation, concrete is the principal material use for foundations, with some steel for reinforcement. The stability of the building depends on its foundation thus it’s important to ensure that these materials are of satisfactory qualities. Foundations are generally broken into two categories: Shallow foundations Deep foundations.

SHALLOW FOUNDATION Shallow foundation are usually embedded a meter into the soil. One common type is the spread foundation which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from wall and columns to the soil or bedrock. Another common type is the slab-on-grade foundation where the weight of the building is transferred to the soil through a concrete slab placed at the surface.

DEEP FOUNDATIONS Deep foundations are used to transfer a load from a structure through an upper weak layer of soil to a stronger deeper layer of soil. There are different types of deep foundations including piles, impact driven piles, drilled shafts, caissons, piers, and earth stabilized columns. The naming conventions for different types of foundations vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, and pre-tensioned concrete. Recently, engineers now design foundation taking into consideration seismic

condition. This kind of foundation is call Earthquake-protective foundations.

BEARING WALL SYSTEM A load-bearing wall or bearing wall, is one in which a wall of a structure bears the weight and force resting upon it, conducting the vertical load from the upper structure to the foundation. Load-bearing walls are one of the earliest forms of construction. APPLICATION Depending on the type of building and the number of stories, load-bearing walls are gauged to the appropriate thickness to carry the weight above it. Without doing so, it is possible that an outer wall could become unstable if the load exceeds the strength of the material used, potentially leading to the collapse of the structure

POST AND LINTEL • This is the simplest of structural systems. • It is made up of a vertical column that transfers the load of the horizontal lintel to the ground. • This is the main construction system of ancient Egyptian temples and Greek architecture. • It is also the most common form of modern construction

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• Other available structural systems include shells, air supported structures, cable supported structures etc.

Every construction material & system has its own characteristics which to a greater or less extend influence the layout, span length, construction depth, stability system, etc. This is also the case for precast concrete, not only in comparison to steel, Wood, & masonry structures, but also with respect to cast in-place concrete.

PRECAST BUILDING SYSTEM Architectural precast concrete provides architects with an exciting medium when designing facades for a wide range of buildings, from healthcare facilities to shopping malls, commercial office buildings to sports stadiums. Most of its members include; • Precast concrete frame • Precast concrete wall • Precast concrete floor PRIMARY FUNCTIONS SECONDARY FUNCTIONS Keep water out prevent air leakage control light Control radiation of heat control conduction of heat control sound

Resist wind forces control water vapour adjust to movement thermal & moisture expansion/contraction structural movements resist fire Weather gracefully Easy to install

Precast concrete frames involve an entire structure being fabricated off-site. In addition, structural components can be supplied for incorporation into a structure onsite. Frames can simultaneously achieve both structural and decorative design requirements - a wide variety of mixes, colours and finishes can be accommodated. Precast wall are used for internal & external walls, lift shafts, central cores etc. Precast wall systems are mostly used in domestic construction, both for individual housing & for apartments. The precast walls can be load bearing or only partition

walls. Precast walls offer the advantage of speed of construction, smooth surface finishing, acoustic insulation & fire resistance.

Likewise, precast concrete floor can either be; • Hollow core floors • Ribbed floors • Concrete roof elements • Massive slab floors • 3D panels with shotcrete technology for villas.

TENDENCIES IN PRECAST CONCRETE Structural efficiency Flexibility in use Optimum use of materials Speed of construction Quality consciousness Adaptability Protection of the environment Advantages of Precast Concrete  less expensive than real brick.  does not require an extensive footing like a real masonry wall. Can be reset should it ever shift.  More durable than real masonry - no mortar joints to let water in.  Installs quickly and easily - most can be done in one day.  Maintenance free - No need to paint or periodically replace slats as you would with wood fences.

Disadvantage of precast concrete  System building is less flexible in its design concept than purpose-mode structures  Most design briefs can be fulfilled without too much modification to the original concept  Structural connection between the precast concrete units can present both design & contractual problems CAST-IN-PLACE CONCRETE SYSTEM

Cast-in-place concrete consists of concrete which is poured into forms, onto decking, or on the ground at its final location in the building. Although cast-inplace concrete has many typical uses (such as slabs on grade or topping for roof and floor decks), this use of concrete is probably the most expensive and the

slowest of structural systems available. Cast-in-place concrete can be a competitive solution for high-rise buildings if the structural components also are used for floor, ceiling and wall components.

CONCRETE Romans were the first during civilization to use concrete. They used it to achieve very big structures with huge interiors. Use of concrete was discontinued in the middle Ages. Came into use again after 1824 when Portland cement was developed. The addition of steel reinforcement that followed this development increased the use of concrete as a construction material.

COMPOSITION OF CONCRETE The main composition of concrete is; a) Cement b) Aggregate c) Sand d) Water e) Admixtures (if required)

The advantages of concrete are;      

its fire resistance, inexpensive manufacturing process, durable nature, its structural versatility, High compressive strength and Ability to pre-cast it

Its major disadvantages are;  The fact that casting must be controlled, and so it cannot be mixed far away from the site.  It is also subject to rapid deterioration in hostile environments

STEEL Steel became popular after 1856, when H. Bessemer developed a process for introducing carbon into the smelting process. Steel, as used in a structural system, typically consists of steel beams, columns and floor and roof decks.

Typical shapes Angle Structural steel shape resembling L. Used in trusses and built-up girders. Channel Structural steel shape which has a cross-section resembling [. Used in trusses and builtup girders. Plate Sheet steel with a width of more than eight inches, with a thickness ranging from one quarter of an inch to more than one. Flat-rolled steel Reinforcing Bar (Rebar) Sheet

The advantages of steel are

 Its extreme strength and rigidity,  Its superior joining capabilities and the fact that you can have a highly controlled manufacturing process for it.  Structural steel generally is more economical as a framing system than concrete. Structural steel typically takes less time than concrete to fabricate and erect.  Steel is a more economical means of spanning open spaces such as dayrooms.  Steel is a very durable material if detailed properly. One disadvantage is the need to fireproof structural members in many instances, although this cost alone doesn't make it more expensive than concrete. It becomes more expensive when the fireproofing also must be covered by expensive finish systems that are accessible to inmates. The cost can be more than concrete. Moreover, it liquefies when subjected to very high temperature.

WOOD This structural system consists of wood columns, beams and framing for floors, roofs and walls, as commonly found in smaller commercial or residential buildings of up to three floors. It’s among earliest materials used in construction  Early stone age people built huts with wood  Currently used for Post and Beam and frame construction  Also used for interior decoration and furnishing

Major advantages of wood are:  its compressive and tensile strength,  the ease in shaping and carving it,  its lightweight and  abundant supply

Major disadvantages are:  its inflammable nature,  its subjectivity to rot and insect damage and  the limitation in its length

Composite of wood Element Carbon Hydrogen Oxygen Nitrogen Ash

% of dry weight 49 6 44 Slight amount 0.2 – 1.

BRICK  Brick is used in locations where there are no wood and stone.  Romans were among the first civilizations to use brick extensively.  They also used brick as a formwork for concrete.  Commercial mass production of brick introduced in 1628 made brick the predominant building material in England. Manufacturing processes for brick Various process are been used for brick manufacture, some of which are; • Stiff Mud - Extrusion Process • Soft Mud - Moulding Process

Kind of brick shapes

Advantages of brick include  lightweight,  its uniform size, density and color, and  the fact that it can be manufactured in a variety of colors, textures and sizes

Disadvantages include  the labor intensive installation process,  its ineffectiveness in tension and  Mortar used in bonding brick is usually the weakest element and vulnerable to water penetration.

Quantities standards of some building materials

IRON • Iron became popular in after Thomas Darby discovered in 1777 that high temperature causes iron to liquefy and become malleable. • The first architectural applications were in bridges and railroads. • Cast iron (2-4% carbon) was used for structural applications and wrought (0.1% carbon) iron for ornamental work.

The advantages of iron are – its high strength, – light nature and – mass production potential

Its disadvantages are – its subjectivity to corrosion and – its brittle nature

STONE The Ancient Egyptians used stone extensively. Stone was also the favored building material of the Mycenaean and Greek people. Stone construction varies by location depending on the type of stone available. Types of stone The types of stone in construction are;       

Granite Limestone Marble Travertine Sandstone Bluestone Slate.

GRANITE: A very hard, crystalline, igneous rock, gray to pink in color, composed of feldspar, quartz, and ferromagnesian materials. Black "granites" are similar to true "granites" in structure and texture, but are composed of different minerals (basalt, gabbros, and diabase).

LIMESTONE: A sedimentary rock composed primarily of calcite or dolomite. The varieties of limestone used as dimensional stone are usually well consolidated and exhibit a minimum of graining or bedding direction.

MARBLE: A metamorphic (re-crystallized) limestone capable of being polished and used for architectural and ornamental purposes. The color varies including white, black, yellow, red, and green, and frequently beautifully veined or clouded.

The advantages of stone are – its compressive strength, – its ornamental and sculptural value, and – its durability

Its disadvantages include – Poor tensile strength, – Excessive weight, and – High cost in quarrying and finishing Other materials that are commonly used in contemporary buildings include: – aluminium, – glass, – plastics, paper, – lead, – synthetics, – canvass, – And new materials continually developed for new uses.

Compressive Strength & Density of building materials Brick

2500 psi

100-140 pcf

CMU

1900 psi

75-135 pcf

Limestone

3000 psi

130-170 pcf

Sandstone

4000 psi

140-165 psf

Marble

9000 psi

165-170 pcf

Granite

15,600 psi

165-170 pcf

MOTAR It’s a bonding material like cement as earlier mentioned above. It is divided into four categories;    

Type M Type S Type N Type O

Functions:     

Bonding Sealing against Air and Water Accommodating Small Movements Levelling Securing Reinforcement

Proportion & Strength Specifications

Mortar

Portland Cement

Hydrated Lime

Aggregate

Strength

M

1

1/4

2 1/4 ~ 3

2500 psi

S

1

1/4 ~ 1/2

2 1/4 ~ 3

1800 psi

N

1

1/2 ~ 1 1/4

2 1/4 ~ 3

750 psi

O

1

1 1/4 ~ 2 1/2

2 1/4 ~ 3

350 psi

SPACE STRUCTURAL SYSTEMS General Introduction The term 'space structure' refers to a structural system that involves three dimensions. This is in contrast with a 'plane structure', such as a plane truss, that involves no more than two dimensions. Space structures, encompasses  grids,  barrel vaults,  domes, towers, cable nets,  membrane systems,  foldable assemblies and  Tensegrity forms. Space structures covers enormous shapes and are constructed using different materials such as; steel, aluminium, timber, concrete, fibre reinforced composites, glass, or a combination of these. Space structures may be divided into three categories, namely,   

'lattice space structures' that consist of discrete, normally elongated, elements, 'continuous space structures' that consist of components such as slabs, shells, membranes, and 'Biform space structures' that consist of a combination of discrete and continuous parts.

Space structures are been classified into; frames, trusses, arches, vierendeel girders.

FRAMING SYSTEM Framing( light frame construction), is a building technique based around structural members, usually called studs, which provide a stable frame to which interior and exterior wall coverings are attached, and covered by a roof comprising horizontal ceiling joists and sloping rafters (together forming a truss structure) or manufactured prefabricated roof trusses, all of which are covered by various sheathing materials to give weather resistance. When steel is used it’s called steel frame system comprising of vertical steel Column and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The development of this technique made the construction of the skyscraper possible.

A two-story wooden-frame house under construction

Steel framed housing development.

Multiple parts of the building could be framed, some of which include, Wall Conner Exterior wall Interior partitions Lintels (headers) The kinds of framing system commonly used nowadays are;

Balloon framing: Balloon framing is a method of wood construction used primarily in Scandinavia, Canada and the United States. It utilizes long continuous framing members (studs) that run from sill plate to eave line with intermediate floor structures nailed to them. Though wood is a conventional material in this kind of area and readily available however, as a construction method the Balloon framing has several disadvantages 1. The creation of a path for fire to readily travel from floor to floor. 2. The lack of a working platform for work on upper floors. The requirement for long framing members. 3. In certain larger buildings, a noticeable down-slope of floors towards central walls, caused by the differential shrinkage of the wood framing members at the perimeter versus central walls.

Platform framing: The framed structure sits atop a concrete (most common) or treated wood foundation. Mostly wood is used. However, wood isn’t the only material being imposed, metal plates also are used in some areas.

Light-gauge metal stud framing

Light-frame buildings are often erected on monolithic concrete slab foundations that serve both as a floor and as a support for the structure. Other light-frame buildings are built over a crawlspace or a basement, with wood or steel joists used to span between foundation walls, usually constructed of poured concrete or concrete blocks.

Truss Construction Until the 1960s, almost all truss systems were two-dimensional. They had developed from timber roofs, which themselves had evolved from a basic triangular arrangement to more complex shapes. Trusses are defined as structural systems in which the members are interlinked so that they are only subject to axial compressive or tensile forces. A truss is structural members joined together to form ridged frame work of a structure.

Advantages of truss:      

Over 60% of today’s structures use truss systems Truss material is lighter and less expensive Can be found in roof and floor systems Trusses allow for larger openings in areas of a structure Easier and safer to handle during construction Able to support heavy loads under normal conditions

Types of Trusses  Heavy Timber Floor and Roof Trusses  Light timber Floor and Roof trusses most common!  Metal Floor and Roof Truss systems

Heavy Timber Truss Systems Characteristics  Usually used to create large clear areas like Cathedral Ceilings  Bolts are commonly used to connect truss members  Most common form of construction in commercial structures.

Light Weight Wooded Truss Systems Characteristics  Made from 2x4, 2x6, and 2x8 sized lumber  Found mostly in single family dwelling  Uses the lightest weight lumber necessary to support the anticipated load  Gusset plates are usually used to connect truss system members.

Metal Truss Systems Characteristics    

Much stronger than Timber Most common in commercial structures Can be found in combination with other materials May use cable in the truss web.

Heavy metal truss

Types of truss designs Triangular Trusses

 Are the most common trusses used in single-family dwellings?  Triangular trusses provide a peaked roof

Scissor Trusses

 Are common in construction with cathedral ceilings.  They are often found in churches.

Parallel Chord Trusses

 Provide a flat roof or floor.  The top and bottom chords are parallel.  They are commonly used in single-family dwellings, row houses, apartment buildings, and smaller office buildings.

Bowstring Trusses

 Get their name from the curved shape of the top chord.  Parapet walls may hide the curved roofline on large commercial buildings.

Inverted king/queen post trusses

They are used in place of support columns to provide open floor space under the truss. Forms of trusses

ARCHES An arch is a structure that spans a space while supporting weight (e.g. a doorway in a stone wall). Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture, but their systematic use started with the Ancient Romans who were the first to apply the technique to a wide range of structures.

Construction process An arch requires all of its elements to hold it together, raising the question of how an arch is constructed. One answer is to build a frame (historically, of wood) which exactly follows the form of the underside of the arch. This is known as a centre or centering. The voussoirs are laid on it until the arch is complete and self-supporting. For an arch higher than head height, scaffolding would in any case be required by the builders, so the scaffolding can be combined with the arch support.

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Types of arch

Triangular arch Round arch or Semicircular arch

Lancet arch

Equilateral pointed arch

Horseshoe arch

Three-centred arch

Ogee arch

Reverse ogee arch

Segmental arch

Unequal round arch or Rampant round arch

Shouldered flat arch

Three-foiled cusped arch

Elliptical arch

Inflexed arch

Tudor arch

Catenary or Parabolic arch

Other types

A blind arch is an arch in filled with solid construction so it cannot function as a window, door, or passageway. A dome is a three-dimensional application of the arch, rotated about the center axis. Igloos are notable vernacular structures making use of domes. Natural rock formations may also be referred to as arches. These natural arches are formed by erosion rather than being carved or constructed by man. See Arches National Park for examples A special form of the arch is the triumphal arch, usually built to celebrate a victory in war. A famous example is the Arc de Triumphed in Paris, France. A vault is an application of the arch extended horizontally in two dimensions; the groin vault is the intersection of two vaults.

Stone arch in Yemen

VIERENDEEL GIRDERS Characteristics  They occupy large horizontal span.  They don’t require bracings

Schematic forms of vierendeel girders and frames

Features of vierendeel girder at Yale University

Vierendeel facade

Vierendeel element

Cross section

Vierendeel/ floor girder joint detail

During construction

after construction

REFERENCES Essence book on building- general editor J.H Cheetham, A.R.B.A ( V.C launder) Reinforced concrete fundamentals (Phil M. Ferguson) o 4th Edition S.I version Building Construction Materials and types of Constructions o Huntington Mickadeit o 5th edition o www.shilstone.com Bowyer, J. L., and R. L. Smith, 1998. The Nature of Wood and Wood Products, University of Minnesota, Forest Products Management Institute, Minneapolis, MN, 1998. Steel structures (design and behaviour) 2nd edition o Salmon Johnson. National Design Specification for Wood Construction, American Forest and Paper Association, o Washington, DC, 1997. http://www.cispi.org/handbook.htm http://www.wsdot.wa.gov/fasc/EngineeringPublications/Manuals/S S2004.PDF 

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[1] International Journal of Space Structures (currently in its twelfth volume), Editors: H Nooshin and Z S Makowski, Published by MultiScience Publishing Co Ltd, 107 High Street, Brentwood, Essex CM14 4RX, UK [2] Makowski, Z S. Steel Space Structures, Michael Joseph Ltd, London, 1965 G Sherwood, RC Moody (PDF). Light-Frame Wall and Floor Systems. United States Department of Agriculture Forest Service Forest Products. http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr59.pdf.

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