comparision between manual analysis and …dsresearchcenter.net/pdf/v2_i17/v2-i17-2.pdf · the...

DURGA RAO U, et al, International Journal of Research Sciences and Advanced Engineering [IJRSAE]TM Volume 2, Issue 17, PP: 14 - 22, JAN - MAR’ 2017.

International Journal of Research Sciences and Advanced Engineering

Vol.2 (17), ISSN: 2319-6106, JAN - MAR’ 2017. PP: 14 - 22

COMPARISION BETWEEN MANUAL ANALYSIS AND STAAD PRO.

ANALYSIS OF MULTI STOREY BUILDING

U DURGA RAO 1*, B BEERAIAH 2*, M V NARASAIAH 3*, Dr. Y RAMESH BABU 4*

1. Student, Dept of CIVIL, VELAGA NAGESWARA RAO COLLEGE OF ENGINEERING. 2. Dept of CIVIL, VELAGA NAGESWARA RAO COLLEGE OF ENGINEERING.

3. HEAD-Dept of CIVIL - VELAGA NAGESWARA RAO COLLEGE OF ENGINEERING. 4. Principal - VELAGA NAGESWARA RAO COLLEGE OF ENGINEERING.

ABSTRACT

The principle objective of this project is to analyze and design a multi-storeyed building [G + 2 (3

dimensional frame)] using STAAD Pro. The design involves load calculations manually and analyzing

the whole structure by STAAD Pro. The design methods used in STAAD-Pro analysis are Limit State

Design conforming to Indian Standard Code of Practice.

STAAD.Pro is the professional’s choice. Initially we started with the analysis of simple 2

dimensional frames and manually checked the accuracy of the software with our results. The results

proved to be very accurate. We analyzed and designed a G + 2 storey building [2-D Frame] initially for

all possible load combinations dead, live, wind and seismic loads]. STAAD.Pro has a very interactive

user interface which allows the users to draw the frame and input the load values and dimensions. Then

according to the specified criteria assigned it analyses the structure and designs the members with

reinforcement details for RCC frames. We continued with our work with some more multi-storeyed 2-D

and 3-D frames under various load combinations. Our final work was the proper analysis and design of a

G + 2 3-D RCC frame under various load combinations.

The materials were specified and cross-sections of the beam and column members were

assigned. The supports at the base of the structure were also specified as fixed. The codes of practice to be

followed were also specified for design purpose with other important details. Then STAAD.Pro was used

to analyze the structure and design the members.

INTRODUCTION

Buildings constitute a part of the definition of

civilizations, a way of life advanced by the

people. The construction of buildings should be

looked upon as a process responded to human

requirements rather than as a product to be

designed and built a great expense.

A building is a structure with a roof and walls

standing more or less permanently in one place,

such as a house or factory. Buildings come in a

variety of sizes, shapes and functions, and have

been adapted throughout history for a wide

number of factors, from building materials

available, to weather conditions, to land prices,

ground conditions, specific uses and aesthetic

reasons. To better understand the term building

compares the list of non-building structures.

Buildings serve several needs of society –

primarily as shelter from weather, security,

living space, privacy, to store belongings, and to




comfortably live and work. A building as a

shelter represents a physical division of the

human habitat (a place of comfort and safety)

and the outside (a place that at times may be

harsh and harmful).

Ever since the first cave paintings, buildings

have also become objects or canvases of artistic

expression. In recent years, interest in

sustainable planning and building practices has

also become an intentional part of the design

process of many new buildings.

Single-family residential buildings are most

often called houses or homes. Residential

buildings containing more than one dwelling

unit are called a duplex, apartment building to

differentiate them from 'individual' houses. A

condominium is an apartment that the occupant

owns rather than rents. Houses may also be built

in pairs (semi-detached), in terraces where all

but two of the houses have others either side;

apartments may be built round courtyards or as

rectangular blocks surrounded by a piece of

ground of varying sizes. Houses which were

built as a single dwelling may later be divided

into apartments or bedsitters; they may also be

converted to another use e.g. an office or a shop.

Building types may range from huts to multi-

million dollar high-rise apartment blocks able to

house thousands of people. Increasing settlement

density in buildings (and smaller distances

between buildings) is usually a response to high

ground prices resulting from many people

wanting to live close to work or similar

attractors. Other common building materials are

brick, concrete or combinations of either of

these with stone The dimensions of the interior

rooms are fixed as per the guidelines of national

building code. Each that is provided with all the

basic amenities and requirements like bedroom

with attached bath, a living cum dining room

and a kitchen, as described above. Sufficiently

large doors and windows in good number are

provided for better ventilation. A special feature

of this building is the provision of ventilation

from all sides as possible i.e., from bath rooms

and bed rooms. Each flat has got main entrance

from a common entrance lobby thus take care

not to isolate any flat as a protection against

burglary at the same time maintaining sufficient

privacy. The building is provided with a

spacious staircase to avoid over – crowding.

The building is designed as a framed structure

with brick walls as infill walls. All the exterior

walls are one brick-wall while all the partition

walls are half brick walls. We propose use M20

concrete and Fe415 bars for all structural

components like slabs, beams columns and

Foundation.

Regarding their structural features, they are

rectangular buildings. All the columns are

arranged in such a way that they form typical

frames in length and width direction. The

longitudinal and transverse frames are

analyzed using the Kani‘s method of

analysis. The limit state method of collapse

using IS: 456-2000, and SP-16 have been

adopted for the design of all structural

components like slabs, beams, columns and

foundations.

We have compared the manual analysis results

with the results obtained by using the STAAD

Pro. Software. We have used the AUTO CAD

for effective representation of the plans.




Fig: Plan

LOAD CALCULATIONS

Loads considered:

Dead loads: (from IS-875 part 1)

1. Unit weight of concrete 25kN/m3

2. Unit weight of brick work 19.1kN/m3

3.Floor finishes 1.5 kN/m2

Live loads: (from IS-875 part 2) from Table 1

1.All rooms and kitchens 2 kN/m2

2.Toilet and bathrooms 2 kN/m2

3.Corridor, passages, Stair case, Including tire

escapes and store rooms 3 kN/m2

4.Balconies 3 kN/m2

5.On to the roof(from table 2:access provided)

1.5 kN/m2

STRUCTURAL ANALYSIS:

INTRODUCTION:

Structural analysis deals with the behavior of

structure in the given loading conditions.

Depending upon the nature of loading, the

structure may respond in number of ways. The

structure may deform statistically, might yield

and may vibrate or buckle. Structures carrying

static loading can be classified as statically

determinate and statically indeterminate

structure. If all reactions and internal forces in a

structure can be found using the equilibrium

conditions along that is,

∑Fx =0, ∑Fy =0, ∑Fz=0, ∑My =0, ∑Mz =0.

Then the structure is statically determinate, if

not it is statically indeterminate of redundant

various methods popularly used for analysis

includes

Moment distribution method




Kani‘s method

Substitute frame method

Slope deflection method

Matrix methods

In this project Kani‘s method is used for the

analysis of structure. The reason is, even if a

mistake is committed in distribution in one of

the cycles, it converges finally to the correct

answer i.e. error is self-eliminative. No. of

cycles required for getting the final value are

also less compared to moment distribution

method and it is very quick method. Even today,

many practicing engineers who are not familiar

with computer methods use Kani‘s method for

the analysis of 3 to 4 storey building frames.

KANIS METHOD (OR ROTATION

CONTRIBUTION METHOD) OF FRAME

ANALYSIS:

This method may be considered as a further

simplification of moment distribution method

wherein the problems involving sway were

attempted in a tabular form thrice ( for double

story frames) and two shear coefficients had to

be determined which when inserted in end

moments gave us the final end moments. All

these effort can be cut short very considering by

using this method.

Fig: load drawing




Fig: Resultant Shear force diagram with SF

values at the support:

Fig:Resultant displacement diagram at mid span

Frame analysis is carried out by solving

the slope – Deflection equations by successive

approximations. Useful in case of side sway as

well.

Operation is simple, as it is carried out

in a specific direction. If some error is

committed, it will be eliminated in a subsequent

cycles if the restraining moments and

distribution factors have been determined

correctly. Please note that method does not give

realistic result in case of columns or unequal

heights within a storey and for pin ended

columns both of these cases are in fact

extremely rare even in actual practice. Even

codes suggest that RC columns framing into

footing or members above may be considered

more or less as fixed for analysis and design

purpose.

DESIGN PHILOSOPHIES

INTRODUCTION

Introduction to limit state design:

Before the last two decades the structural

designers of reinforced concrete were concerned

more with safety against failure of the structure

than with durability under service conditions.

The theoretical calculations for design of R.C.C

structure were based on classical elastic theory,

fictitious modulus of Elasticity of concrete and

permissible working stresses, recent

developments lead to limit state design

otherwise called strength and performance

criteria based on the recommendation of

International code of practice different countries

started changing their codes introducing limit

state design for the design of reinforced concrete

structures.

India introduced limit state design for the design

during the revised IS: 456-2000 along with

working stress method of design. IS:456-2000

permits design of R.C.C structural design by

both working stress method and limit state

method.

As has happened in the other scientific field new

ways of thinking replace old ways. In scientific

circles this is generally referred as Paradigm

shift limit state design should therefore looked

upon as a paradigm a better way of explaining

certain aspects reality and new way us of

thinking about old problems. Thus the design

should be learnt and taught with own philosophy

and not as an extension of old elastic theory.

Since the rational approach to design of

reinforced concrete did not mean simply

adopting the existing method of elastic and

ultimate theories. New concepts with a semi




probabilistic approach to design were found

necessary the proposed new method had to

provide a framework, which would allow a

design to be economical and safe. The new

philosophy of design was called the limit state

method of design

CONCEPT OF LIMIT STATES

In the method of design based on limit state

concepts the structure shall be designed to

withstand safely all loads to act on it throughout

its life, it shall also satisfy the serviceability

requirements such as limitations on deflection

and cracking. The acceptable limit for the safety

and serviceability requirements before failure

occurs is called limit state. The aim of the design

is to achieve acceptable probabilities that the

structure will not become unfit for the use for

which it is intended, i.e., that it will not reach a

limit state.

All relevant limit state shall be considered in

design to ensure an adequate degree of safety

and serviceability. In general the structure shall

be designed on the basis of the most critical limit

state and shall be checked for other limit states.

For ensuring above objective, the design should

be based on characteristic values for material

strengths and in the loads to be supported, the

characteristic values should be based on

statistical data; if available where such data are

not available they should be based on

experience. The design values are derived from

the characteristic values through the use of

partial safely factors, one for material strengths

and other for load. In the absence of special

consideration these factors have values given in

IS: 456 – 2000 according to the material the type

of loading and the limit state being considered.

PARTIAL SAFETY FACTORS

Ultimate load theory is based on the assumption

that a structure reaches a collapse condition

forming a mechanism when a certain load is

applied. The load factor has been judiciously

selected giving due considerations to the various

factors contributing the failure. The load factor

is used in estimating ultimate loading.

Partial safety factor for material, strength should

account for,

•Possibility of deviation of the strength of

material.

•Deviation of structural dimensions.

•Deviation of structural dimensions.

•Accuracy of the calculations procedure.

•Risk to like and economic consequences.

When assuming the strength of a structure for

limit state of collapse. Value of partial safety

factors should be taken into account for,

Partial safety factor for concrete = 1.5

Partial safety factor for steel = 1.15

Partial safety factors for loads should account

for

•Unusual increasing loads beyond that using for

deriving characteristic values.

•Unforeseen stress distribution. \

•In accurate assessment of the effect of loading.

Partial safely factors of loads under different

conditions are given in clause 35.4 of IS: 456 –

2000.

SLAB DESIGN




Fig: slab detailing

DESIGN OF BEAMS

Column detailing

STAIRCASE DETAILING




CONCLUSION

•Planning has been done in accordance with the

specifications made by NATIONAL

BUILDING CODE.

•Used AUTOCAD 2010 for effective

representation of drawings.

•Since spans differ by more than 15% with

largest, we went for exact analysis method.

•Manual analysis results are compared with the

STAAD results and identified that the variation

is at max 5%.

•Used IS-456:2000 & SP-16, for the design of

the STRUCTURAL MEMBERS. i.e., fallowed

the LIMIT STATE method.

•Materials used are M 20 grade concrete and Fe

415 steel.

REFERENCES

1.Indian Standard PLAIN AND REINFORCED

CONCRETE - CODE OF PRACTICE ( Fourth

Revision ) IS:456-2000

2.IS-875(PART-1) : 1987 Indian Standard

CODE OF PRACTICE FOR DESIGN LOADS

(OTHER THAN EARTHQUAKE) FOR




BUILDINGS AND STRUCTURES PART 1

DEAD LOADS — UNIT WEIGHTS OF

BUILDING MATERIALS AND STORED

MATERIALS.

3.IS-875(PART-2) : 1987 Indian Standard

CODE OF PRACTICE FOR DESIGN

LOADS (OTHER THAN EARTHQUAKE)

FOR BUILDINGS AND STRUCTURES

PART 2 IMPOSED LOADS

4.SP-16: DESIGN AIDS FOR REINFORCED

CONCRETE TO IS : 456-l 978

5.Indian Standard CODE OF PRACTICE FOR

DESIGN AND CONSTRUCTION OF PILE

FOUNDATIONS PART Ill UNDER-

REAMED PILES (First Revision) IS : 2911 (

Part III ) – 1980

6.R.C.C. DESIGNS (reinforced concrete

structures) by Dr.B.C.PUNMIA, ASHOK

KUMAR JAIN, ARUN KUMAR JAIN (Tenth

edition), LAXMI PUBLICATIONS (P) LTD.

7.Building planning and drawing by Dr.

N.Kumara swamy and A. Kameswara rao(fourth

revised and enlarged edition:2010), Charotar

publishing house Pvt. Ltd.

8.AUTOCAD-2010

9.STAAD Pro. software

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