Post lintel structure

Presentation on Post-lintel structure

Presented byTonmoy Barua 132082001

Nizam Uddin 141081005

Presented to,Ar. Mehreen HossainDept. of Architecture

ContentDefinitionLoads on structureLoad transferring system Foundation• Wall Footing• Column Footing• Combined Footing

Structural Types • Framed structure• Load bearing structure

Column – Beam structural systemColumn – Beam connectionConventional approachPunch in post- lintel structureStructure in staircaseThumb rulesAdvantages and DisadvantagesCase studyExamplesReferences

DefinitionA structure is a system of inter connected elements to carry loads

safely to under ground earth.

• Structures have defined boundaries within which each element is physically or functionally connected to the other elements.

• In structure elements themselves and their interrelationships are taken to be either fixed (permanent) or changing only occasionally or slowly.

Loads on structure• DEAD LOAD• LIVE LOAD

Live loads may be fully or partially in place or present at all. They may change in location.

Dead load is a constant load in a structure that is due to the weight of the members, the supported structure, and permanent attachments or accessories.

Most lateral loads are live loads. Typical lateral loads would be a wind load against a facade, an earthquake, the earth pressure against a basement wall.

Mainly there are 2 types of loads :

LATERAL LOAD• WIND LOAD• EARTHQUAKE LOAD

Load transferring system Load Dead load and Live load

Lintel

Columns

Footings

Ground

FoundationThe foundation is the part of a structure that is usually placed below the surface of the

ground & that transmits the load to the underlying soil or rock.

TYPES OF FOUNDATIONFOOTING

Wall Footing R.C.C. Wall Masonry Wall

Column Footing• Rectangular • Square

Combined Footing Pile Mat, Raft or Deep Foundation

Structural Types Basically in building structures there are 2 types of structures:

(1) load bearing structure. (2) framed structure

A load-bearing wall or bearing wall is a wall that bears a load resting upon it by conducting its weight to a foundation structure.

Framed structures are the structures having the combination of beam, column and slab to resist the lateral and gravity loads.

COLUMN-BEAM STRUCTURAL SYSTEMCOLUMNColumns are vertical support members subjected to compressive loads. They are also referred to as pillars, posts, stanchions and struts. They transmit loads from the upper floors to the lower levels and then to the soil through the foundations.

Classification on the basis of shape• Rectangular column• Square column• Circular column• L -section• T -section

TYPES OF COLUMNClassification on the basis of Reinforcement• Tied column• Spiral column• Composite column• Pipe column/ Concrete fill column

COLUMN-BEAM STRUCTURAL SYSTEMBEAMA beam is a horizontal pole. It is usually shaped as a rectangle so there is more balance between the poles. A beam is held up by one or two columns. • If there are two columns, they are placed on either side of the beam.

• If there is one column, it is placed in the middle of the beam so each side is balanced.

TYPES OF BEAMAccording to Reinforcement• Single reinforcement beam• Double reinforcement beam

SINGLE REINFORCEMENT BEAM SECTION (USED IN TENSILE ZONE)

DOUBLE REINFORCEMENT BEAM SECTION ( USED IN TENSILE AND COMPRESSED ZONE)

According to Support

• Simply Supported Beam• One end Continuous Supported Beam• Both end Continuous Supported Beam• Cantilever Beam

Simply Supported Beam

20

One end Continuous Supported BeamBoth end Continuous Supported Beam

COLUMN-BEAM STRUCTURAL SYSTEM Cantilever Beam

A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is forced against by a moment and shear stress. Cantilevers can also be constructed with trusses or slabs.

Cantilever Beam

COLUMN-BEAM (SLAB) STRUCTURAL SYSTEM

One-way slabA one-way slab is essentially a rectangular beam of comparative large ratio of width depth. And steel use to short direction of slab.

There are two type of slab use in Column- Beam structural system

Two way slabMost rectangular reinforced concrete slab are supported on all four side by beam , girders or walls.

Column – Beam connection

• Beams are all set on bearing pads on the column corbels

• Steel angles are welded to metal panels cast into the beams and columns and the joint is grouted solid

Joint demands

moments, shears, axial loads acting on joint

Joint geometry

Interior Corner Exterior

Structure in staircaseIN THE POST LINTEL STRUCTURE THERE USED THREE TYPES OF STAIR SECTION.

1. BEAM HANGING FROM LANDING LEVEL.2. BEAM INVERTED ON LANDING LEVEL.3. BEAM HANGING FROM SAME AS SLAB LEVEL.

BEAM HANGING FROM LANDING LEVEL. BEAM INVERTED ON LANDING LEVEL. BEAM HANGING FROM SAME AS SLAB LEVEL.

Conventional approach• Assume load transfer in One-Way or Two-Way manner• Assume beams to support the slabs in similar ways as

walls• Design slabs as edge supported on beams• Transfer load to beams and design beams for slab loadLoad transferring system

Transfer of Area Load

To Points

Transfer of Area Load

To Lines and Points

Transfer of Area Load To Lines

Single Path Slab

On Walls

Single Path Slab

on ColumnsDual Path Slab On

Beams, Beams on Columns

WallWall must be placed over a beam. As wall does not carry any load opening can be created anywhere of the wall,100% opening in wall surface is possible.

Punch

Punched on the slab can be obtained without any

disturbance.

L/2 L/4L/4

Not possible

possible

possible

Thumb rulesThree thumb rules of column to be followed are as follows:Size of the ColumnsDistance between ColumnsAlignment of columns

Thumb rule no.1- Size of the columns:• The size of the columns depends on the total load on the columns.• Minimum size of the column should not be less than 9”x9”. 9”x9” columns are to be used for a single storey structure with M15 grade of concrete. In case, 9”x9” column size is to be used for 1 and half storey structure, then it is advised to use M20 grade concrete.• A safe and structurally sound column size for a 1 and half storey

structure should not be less than 12”x9” using M15 grade concrete. This should be in your most

preferred and practical options list.Thumb rule no.2: Distance between the columns• Try to maintain equal distance between the centers of two columns. Always plan a column layout on a grid. • The distance between two columns of size 9”x9” should not be more than 4m centre to centre of column.• If larger barrier free distances are required then going for larger column size is to be used

The size of the columns increase because of two factors:Increase in the distance between two columns (This increases the dimensions of the columns as well the depth of the beam.)Height of the building (Increase in the number of floors is directly proportional to the dimensions of the columns. Thumb rule no.3 : Alignment of ColumnsA rectangular grid is to be made for placing the columns. This helps in avoiding mistakes and placing in columns can be done in the right way.The columns can preferably be arranged in two different fashions:In a straight line with the help of a gridIn a circular fashion for circular buildings.

Thumb rules

Here we usually design beam spans up to 20-22 ft (approx.) and cantilever slabs spans up to 6-8 ft (approx.) without any special considerations.

Span for Reinforced concrete beams and Cantilever slabs

BEAM THICKNESSClear span of column & the beam thickness is convert to inches for column span length. For an example column span clear 20’-0” so for this region beam thickness 20” for this span

Thumb rulesTwo thumb rules of beam to be followed are as follows:

• Span of RCC beam• Size of the Beam

Advantages and DisadvantagesADVANTAGES

AESTHETICS•Sometimes the heavy or rigid masses are treated politely by using the framework of the post-lintel which gives an extra ordinary looks.

SPAN & SPACE•Larger span (column to column distance) of building is possible.

ECONOMIC•The maintenance cost of this system remains lower than the other structural system for its long lasting characteristics.

CLIMATE•Considering the climate this system is more suitable for our country.•The control of openings admits the little amount of heat in the building.•For the free flowing plan light and ventilation can easily insert the building.

ENVIRONMENT• This structural system having less self-loads which reduces the risk of danger of earthquake. • It can resist the buckling or bending effect of the building from the strong wind flow. • It has the capability of fire resistance for the construction material (R.C.C.).

CONSTRUCTION TECHNICS•In this structural system construction process takes a long time for the casting of beam and slab•In post-lintel system ducting process is not so easier compared to Post-slab.

OPENNINGS•In post-lintel system 50% area of the external facade is remaining for the openings of the building. •For this there is a control over use of openings.

SUSTAINABILITY•This system has less possibility of failure than the other structural system.

Advantages and DisadvantagesADVANTAGES

Advantages and Disadvantages

FLOOR SLAB•Floor slab is a slab supported on ground generally distribute load to the ground uniformly.• It also increases the bearing capacity of soil as the load distributes combined.

SOLID-VOID RATIO•By using the framework of post-lintel system we can make a sense full solid-void ratio which illuminate the monotonous effect.

CANTILEVER OR OVERHANG•The portion of any structure that is over hanged without any support termed as cantilever. •Sometimes cantilever construction is economical and looks aesthetically attractive which may become a useful part of that structure.

ADVANTAGES

Advantages and Disadvantages

• Extreme variation of solid is not possible.• Opening should be place considering the post.• Stair must start with respect to a beam.• Building height increases for the beam to get clear Space.• Also duct for air conditioning are used under beam, so floor height increases which is not acceptable for height.• This system more costly (30%more)than wall slab system but economic range can be kept in a lower gird when the span is limited 15’ to 25’.• Uninterrupted vast space can not be created without using vault dome or waffle.•Sometimes this problem creates visual disturbance, which is avoided, in flat slab. •The construction cost of this system is slightly high for the time consuming costing of beam and slab and the use of R.C.C.

DISADVANTAGES

Case Study 1 ( Nagar Bhaban)

NAGAR BHABANARCHITECT: LAILUN NAHAR & ABU H IMAM UDDINLOCATON:DHAKALEVEL: 15BUILDING CONTAINING :•Mayor's Office•Offices•a bank•meeting rooms•a museum•dining facilities•a prayer hall•public terraces.

RCC Wall Slab &Waffle Slab

ADVANTAGES:•MOST COMPACT AND STRUCTURAL SYSTEM.•RECTANGLE GRID IS EASY FOR PARKING.•EARTHQUAKE RESISTANT•STRUCTURAL SYSTEM IS VISUALLY CLEAR.•ENOUGH NATURAL LIGHT•WELL USED SHADING DEVICE.

DISADVANTAGES:•HUGE LOBBY SPACE•UNUSUABLE OPEN TERRACE• UNNESSESARY EXTRA HEIGHT SPACE

Project Name: Mamun ResidenceArchitect: Rafiq AzamHouse no: 67/ARoad:01South khulshiChittagong

Case Study 2Mamun Residence

Case Study 2 ( Mamun Residence)

Ground Floor Plan


1st Floor Plan

2nd Floor Plan

Materials:• Wooden frames• Concrete staircase• Bare concrete frame cast on

site• Brick outer cladding• Bare cement internal walls• Marble and ceramic flooring


Case Study 3 ( SA House)

Project name : SA House Architect : Rahiq AzamTotal useable surface area : 20667 m2Plot size : 11970 m2Location : Road100, Gulshan 1, Dhaka


• Oriented toward the south, where the home is most open to its surroundings.• The courtyard has a glass roof which lets light, wind and rain through, creating an ever-changing environmental reservoir.

The floor plan of the three levels reveals a noticeable absence of passageways, as direct communication between different rooms is preferred, without any clear divisions between the spaces.

•Folding doors and windows to permit flexible management of the space as a whole.•This is clearly an introspective building, in which every view and every glimpse of one room from another is designed to encourage observation of space and contemplation of the natural element.


•In the project opens large circular holes in the cement slabs: on the roof, to create the “rain room.•The dark wood frames and the natural green contrast with the neutral cement surfaces designed to be contaminated and “interpreted” over time by the growing vegetation.


Reinforced Concrete Building Construction

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Post lintel structure

Design

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