AN OVER VIEW OF THE HIGH RISE

BUILDINGS

BY

N.KRISHNAM RAJUADVISOR TO APHB

Introduction

In Metropolitan Cities , where the pressure on land is rapidly Increasing due to rapid growth of industry and trend towards Urbanization, vertical expansion is the only answer.

Multi storeyed buildings lead to greater co

ordination Between various departments and their

efficient functioning. General principles of planning and design of multi

storeyed have been discussed.

Generally Building Construction is Classified as :

1. Load Bearing

2. RCC Framed

3. Composite Structure

What is a Project ?In simple term project is one temporary activity with a clear start and a end

The main elements are

1. Time2. Cost3. Resources4. Clear roles and responsibility5. Delivery

Detailed Design :1. Develop detailed design from approved scheme

design.

2. Detailed design will confirm type of construction, quality of materials and standard of workmanship.

Specifications :

Prepare detailed information including

Drawing Schedules

Specification of Materials

Workmanship

Design :

1. Evaluation of design requirements2. Review of compatibility of the design with the plan and

budget.3. Identification of design objectives, design stages, activities

and elements.4. Regular Monitoring of the design development.5. Identification of proposed design changes and their

resolution.6. Assessment of design progress related to the design

schedule.7. Evaluation of as to the completeness of construction

information.8. Review of sample materials and mock ups for compliance

with specifications.9. Identification and arrangement of the final standard of

acceptance of the construction..

Civil Engineering Comprises of

Planning

Design

Construction

Quality Control.

The Main components of Buildings are :1. Earth Work :

1. Excavation of Foundation. 2. Filling in Foundation3. Filling in Basement.4. Open and Pile Foundation

2. Section : Concrete3. Section : Brick masonry / Stone masonry 4. Section : Flooring5. Section : Roofing and Ceiling 6. Section : Plastering, Painting.7. Section : Wood Work8. Section : Structural Steel Work.9. Plumbing Services.10.Miscellanies.

PLANNING

RCC Frame Structures :

1. Generally buildings are constructed in two categories.

2. Framed Structure usually built with column and beam and in filled brick walls.

3. Load bearing structure is usually built with 1 ½ brick thick both for external and internal walls.

The Design of a structure presents two told problems :

1. If has to be so constructed that it serves the need efficiently for which it was intended (Functional design)

2. It has to be strong enough to resist the loads and forces to which it is subjected during its service (Structure design)

The important aspects in the structural design are

1. To determine the loads / forces which the frame work will be required to support.

2. Selection of a suitable structural arrangement and materials of construction.

3. Analyzing the internal stresses in the frame work.

4. Proportioning the members of the frame work.

General Design Consideration :

1. Aim Design :

To provide a safe and economic structure complying to the users requirement.

2.Method of Design :

Structure and structural elements shall normally be designed by limit state method.

Mix design with suitable materials, quality control, adequate detailing and good super vision are equally important.

3. Durability, Workmanship and Materials :

1. Quality of concrete, steel, other materials, workmanship, should be adequate for safety, serviceability and durability.

Type of Construction

1. Load bearing (up to 1 or 2 floor)

2. Reinforced frame (RCC)

3. Composite construction For High rise structures

4. Steel framed construction

5. Concrete walls (shear walls) structures.

4. Choice of mix

Based on the No. of floors and flexural stresses for Beam, slabs and footing and predominant stress in compression for column members.

5. Preliminary design of RCC frame :

For fixing up of tentaive sizes of members of the frame.

6. Detailed design of RCC Frame :

By adopting loads & stresses including seismic forces, giving sectional properties and material properties,. Analysis and design of entire framed structure can be evaluated

FOUNDATIONS

Sub Soil Exploration and Sampling

Adequate knowledge of the sub soil characteristics for safe and efficient design of foundation.

The basic aim of a sub soil exploration is to obtain the strata grapy and physical properties of the soils underlying the site.

Location of ground water level.

Methods of Tests :

1. Open Test : Suitable for shallow depth.

2. Boring : Suitable for deep exploration (like tube, Augur borings) 3. Sub surface sounding.

Geophysical Methods.

1. The samples collected should represent the nature of subsoil.

2. S.B.C. of soils shall be arrived based on shear parameters as per the relevant IS Code – 6403 – 1981.

3. Also necessary to conduct standard penetration test (or) plate bearing test to assess the safe pressure with regard to settlement.

4. The settlement aspect is to be examined carefully in the case of clayey soils.

Foundations :

Depth of foundation is to be decided based on the soil strata from the trial pits / explorations conducted.

Foundation are normally placed below the ground surface.

The purpose of providing a foundation is to distribute the load over a layer area at a uniform rate so that the pressure does not exceed the allowable bearing capacity of soil below :

Objects of Foundations :

Foundations are provided for the following purposes.

1. To distribute the total load coming on the structure on a large area so as to bring down the intensity of load at its base below the safe bearing capacity of the sub – soil.

2. To support the structure.

3. To give enough lateral stability to the structures against wind, rain, earthquake, etc.

4. To prepare a level and hard surface for concreting and masonry work.

5. To transmit the superimposed loads through side friction and end bearing in case of deep foundation

6. To distribute the non-uniform load of the superstructure evenly to the sub-soil.

7. To provide structural safety against undermining or scouring due to animals, flood water etc.,

8. To prevent or minimize cracks due to movement of moisture in case of weak or poor soils.

Foundation :

1. Engineers need to know the character and magnitude of forces in order to design and contact structures.

2. One has to study the system of soil below the earth surface at various levels under ground depending upon the past experience.

3. Repairs to foundations are expensive. Structures should be founded an stable soils.

4. Certain soil deposits wherein wetting of the soil beyond a stress level causes steep reduction in stiffness resulting from disruption of soil structure.

5. Subject to rate of loading, disruption in soil structure takes place at a faster pace than the development of new structural bonds which Leeds to vertical deformation at locations of high stress due to disturbance of soil structures.

6. Problems associated with foundation in clay soils are well known.

7. Swelling clays create large uplift forces on the peripheral walls during rainy season. A reverse situation may arise at region of moderate rainfall when the central region of a building founded on clay soil is prone to swelling during dry spells.

A. Differential settlement due to unconsolidated fill.

B. Differential settlement due to uplift of shrinkage soil, shrink and expand with changes in moisture content.

C. Vertical and diagonal cracker are noticed on external walls.

8. The problem of dampness in buildings requires a systematic

approach to determine the causes of leakage, the source

from which the moisture is derived and measured which are

likely to prove effect ion.

TYPES OF FOUNDATIONS

DETAILING OF FOOTINGS

PILE CAP

PLAN

STARTER BARS

TOP BARS

HORIZONTAL BARS

PILE

CLEAR OVERHANG

100 TO 150

STIRRUPS

SECTION 1-1

BOTTOM BARS

CONCRETEGrades : The Concrete shall be designated as follows :

Group Grade (1) (2)Ordinary M 10Concrete M 15M 20Standard Concrete M25, M 55High Strength M60, M 65Concrete M 70, M 75, M 80

NoteIn the Designation of Concrete M refer to mix and the number to specify compressive strength of 150 MM size cube at 28 days expressed as N/mm2

Workability Of Concrete :The concrete shall be of adequate workability for the placing condition of concrete and can be properly compacted.

How to Achieve Durable Structures :1. The structure should also be designed for

environment loads and detailing done.2. Selection of construction materials.3. Concrete should be impermeable.4. Good construction practices should be followed.5. Planned maintenance.6. Proper specifications.

Durability of Concrete :

1. The materials and mix proportion specified and used should be such as to maintain in integrity to protect embedded steel from corrosion.

2 One of the main characteristics Influencing the durability of concrete is the permeability to the ingress of Water, Oxygen, Carbon Dioxide and Other Deleterious Substances.

3 Impermeability is governed by the constituents and workability used in making the concrete

Factors Influencing Durability :

(a) Environment

(b) Cover to embedded steel

(c) Type and quality of material used

(d) Cement content / W.C.R. of concrete

(e) Workmanship to obtain full compaction and

efficient curing

(f) Shape and size of the member

Exposure Condition :

(1) Mild

(2) Moderate

(3) Severe

(4) Very Severe

(5) Extreme

Production of Concrete :

1. Quality assurance measures are both technical and organizational. The job of quality control and quality assurance would involve quality audit of both inputs as well as outputs.

Inputs OutputsMaterial for Concrete – Concrete in

PlaceWorkmanship in allStages of Batching, Mixing,Transportation, Placing, Compaction, Curing etc.,

Batching :

In Batching Concrete, quantity of both cement and aggregates shall be determined by mass.

R.M.C. :

As per IS 4926Volume batching may be allowed only where weigh batching is not practical.

Form Work :

1. The form work shall be designed and constructed so as to remain sufficiently rigid during placing and compaction of Concrete and to prevent loss of slurry from the concrete.

2. For details regarding design, detailing etc., reference may be as per IS 14687

3. Cleaning and treatment of form workThe face of form work in contact with concrete shall be cleaned and treated with form release agent.

4. Stripping timeForm shall not be released until the concrete has achieved a strength of at least twice the stress to which the concrete may be subjected at the time of removal form work. Details may be as per IS 456 – 2000.

Assembly of Reinforcement :

1 Reinforcement shall be bent and fixed in

accordance with procedure (specified in IS

2502)

2 Bar bending schedule shall be prepared for

all reinforcement work.

3 Reinforcement shall be placed and

maintained in the position shown in the

drawings by providing proper cover blocks,

spaces, supporting bars etc.,

Welded Joints : In reinforcement may be used in accordance with IS 2751 and IS 9417.

Placing Compaction :

1. The concrete shall be placed and compacted before initial setting of concrete commences and shall not be subsequently disturbed.

2. Concrete shall be compacted using mechanical vibration complying with IS 2505, IS 2506, IS 2514 and IS 4656.

3. Over vibration and under vibration of concrete are harmful and should be avoided.

Expansion Joints :

To allow variations in

temperature, expansion joints

in Frames are essential,

normally @ 45meters length be

provided.

TYPICAL EXPANSION JOINT

(REINFORCEMENT DISCONTINUOUS

AT JOINT)25mm WIDE EXPANSION JOINT

FOOTING

Contd…

TYPICAL EXPANSION JOINT

FILLED WITH SEALENT

25mm WIDE EXPANSION JOINT

(REINFORCEMENT DISCONTINUOUS

AT JOINT)

Construction Joints :

1. To comply with IS 11817 to be provided at accessible location to permit cleaning.

Curing :

1 Curing is the process of preventing the loss of moisture from concrete.

2 The prevention of moisture loss from concrete is particularly important if the water cement ratio is low.

CONSTRUCTION JOINT IN FOOTING

- INDICATES DIRECTION OF CONCRETING

PROVISION OF KICKER IS OPTIONAL

CONSTRUCTION JOINT IN COLUMN

- INDICATES DIRECTION OF CONCRETING

Contd……

CONSTRUCTION JOINT IN COLUMN

- INDICATES DIRECTION OF CONCRETING

Contd…

CONSTRUCTION JOINT IN SLAB

- INDICATES DIRECTION OF CONCRETING

CONSTRUCTION JOINT AT BEAM - COLUMN

JUNCTION

- PERMITTED ONLY WHEN

CONCRETING OF

TAKEN UP IMMEDIATELY

AFTER CONCRETING

- INDICATES DIRECTION

OF CONCRETING

A

B

CONSTRUCTION JOINT AT BEAM - COLUMN

JUNCTION

- INDICATES DIRECTION OF CONCRETING

PERMITTED ONLY WHEN

1. SHEAR RESISTANCE OF CONCRETE IS NEGLECTED.

2. INTERFACE TREATED AS HIGH IN THE DESIGNS AND

3. ADEQUATE DEVELOPMENT LENGTH OF PROTRUDING REINFORCING BARS ENSURED.

- INDICATES DIRECTION OF CONCRETING

CONSTRUCTION JOINT AT BEAM - COLUMN

JUNCTION

TYPICAL CONSTRUCTION JOINT IN ONE-WAY SLAB

PLAN

Contd……

CROSS SECTION - TYPICAL

Contd…

TYPICAL CONSTRUCTION JOINT IN ONE-WAY SLAB

1. Moist Curing :

Exposed surfaces of concrete shall be kept

continuously in a damp or wet condition by

ponding or by covering with a layer of sacking,

Canvas etc., for at least 7 days from the date of

placing of concrete in case OPC and 10 days where

mineral admixture / blended cement are used shall

not be less than 10 days for concrete exposed to dry

and hot weather condition

2. Membrane Curing :

Approved curing compound may be used in lieu of

moist curing. Impermeable membrane such as poly

ethylene sheet covering closely the concrete surface

may be used to provide effective barrier against

evaporation.

3. Supervision :

Constant and strict supervision of all the items of

construction is necessary during progress of work.

WALLS :External Walls :

In framed construction, the function of external filler wall is to provide adequate weather protection.

Internal Partition Walls :The Function of Internal Walls is to divide Floor space.

External Finishing1. Generally framed construction with brick filler

walls the external plastering is likely. to crack at Junction of RCC and masonry work.

2. Better to provide chicken mesh at Junction for producing effective bond.

I. Water Supply in Multi Storage Building

Water Supply for :

1. Drinking purpose .

2. Water Closets, Wash Basin.

3. Kitchen, Canteen

4. Fire Fighting

5. Air Conditioning

6.Horticulture Purpose.

II. Sanitary Installation

A Common shaft should be provided for taking all water supply drainage, soil and vent pipes from all water closet room.Sanitary installation should be provided as per IS1172.

III. Drainage Problems :

In Multi Storeyed Building

A. Drainage of the roofB. Drainage of Basement C. Water Proofing of roofs D. Planning for materials E. Norms for room

IV. Air Conditioning of High Rise Buildings

Two Main Types of Air Conditioning Plant.

1. Evaporation Type :

Work on principle of evaporative cooling.

2. Refrigeration Type :

Producing rigid Controlled condition of temperature, humidity.

V. Electrical Lift

Number and location of lifts have to be fixed according to functional requirement of building.

Medium Speed : For 6 to 10 Stages.High Speed : For taller Building.

Details of lift, dimension of lift wall, Lift pit, Machine room have to be essential.

VI. Fire Safety in Multi Storyed Office Buildings :

a. Fire hazard is a a major problem.

b. Niches should be provided on all floors to house the fire fighting equipment.

c. Automatic fire extinguisher devises to be installed; including in door hydrant on each floor.

d. Hydrant should be centrally located.

e. Automatic fire alarm systems are necessary for safe evacuation of the population.

VI. Fire Escapes (IS 1644) :

To assist in quick evacuation of the population of building when on fire.

Types of Constructions :

a. Fire Escapeb. Spiral stairsC. Ladders

C. Ladders

1. All types should be mounted on the outside of building and have direct connection with ground.

2. Materials used to conform IS 1642.

3. Entrances to external escapes should be quite separate.

4. Route to External Escape should be free from any obstruction.

RESIDENTIAL

COMPLEXES