Structural Analysis Report of RCC Building

8/10/2019 Structural Analysis Report of RCC Building

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ABBREVIATIONS

A - Area

bf - Effective width of flange

D - Overall depth of beam or slab or diameter of column;

dimension of a rectangular column in the direction under

consideration

Df - Thickness of flange

DL - Dead load

d - Effective depth of beam or slab

d - Depth of compression reinforcement from the highly

compressed face

EC - Modulus of elasticity of concrete

EL - Earthquake load

Es - Modulus of elasticity of steel

fck - characteristic cube compressive strength of concrete

fy - Characteristic strength of steel

Ief - Effective moment of inertia

K - Stiffness of member

k - Constant or coefficient or factor

Ld - Development length

LL - Live load or imposed load

Lw - Horizontal distance between centers of lateral restraint

l - Length of a column or beam between adequate lateral

restraints or the unsupported length of a columnlef - Effective span of beam or slab or effective length of

column

lex - Effective length about x-x axis

ley - Effective length about y-y axis

ln - Clear span, face-to-face of supports

lx - Length of shorter side of slab

ly - Length of longer side of slab


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ll - Span in the direction in which moments are determined,

centre to centre of supports

l2 - Span transverse to I,, centre to centre of supports

l2 - l2 for the shorter of the continuous spans

M - Bending moment

m - Modular ratio

P - Axial load on a compression member

q0 - Calculated maximum bearing pressure of soil

r - Radius

s - Spacing of stirrups or standard deviation

T - Torsional moment

V - Shear force

W - Total load

X - Depth of neutral axis

Z - Modulus of section

z - Lever arm

f - Partial safety factor for load

m - Partial safety factor for material

m - Percentage reduction in moment

- Creep strain of concrete

cbc - Permissible stress in concrete in bending compression

cc - Permissible stress in concrete in direct compression

sc - Permissible stress in steel in compression

st - Permissible stress in steel in tension

sv - Permissible tensile stress in shear reinforcement

c - Shear stress in concrete

c,max - Maximum shear stress in concrete with shear

reinforcement

v - Nominal shear stress

- Diameter of bar


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INTRODUCTION

Public Hospitals are to be established as per government requirement and

community expectations. According to the present time, public hospital sector handles

the majority of acute care separations and accounts for most regional and remote

hospitals while private hospitals are concentrated in metropolitan areas, and are more

likely to treat patients of higher socio economic advantage. Public hospitals treat

medical cases originated in an area including emergency cases where as in private

sector, cases are selective and opted. These services are separate, not overlapping

between public and private sector.

Public Hospitals are completely and entirely run on the Government funding and

money. Everything from the construction, to the salary of Doctors/Staff, to the medical

equipments, medicines each and every single thing is being taken care of by local

Government. A public hospital is considered to be a preferable option for the not- so-

rich lot of people who despite acute illness cant afford heavy fees of private hospitals.

Although it is very ironical to see that a hospital governed by the Government (who has

obliviously more funds than a group of people or one person alone), does not offer that

level of service which can be counted on in most of the times.

The building is designed for Basement+ Lower Ground + Ground +4 floors.

OPDS, Registration Facilities are planned in Ground floor. Basements are used for

occupying various services like Medical Gases, Laundry, Electrical room, Generator etc.

Operation theatres, Wards, Labour Rooms, pediatrics wards and Nursing Station areplanned in Other Floors. So it is planned to construct Basement+ Lower Ground+ Ground

floors (3 floors) for accommodating the important facilities which is inevitable for the

functioning of M&C Hospital. A Ramp is provided for connecting all the floors. The other

facilities as per the initial planning can construct as future expansion for which the

column and foundations are designed for.

The building foundation was first proposed with column isolated footings based on the

submitted soil report of nearest building. The Sbc recommended by soil expert was

150kN/m2 1.5m from GL. The Building is proposed with two basements, so the founding

level will be 4m below from existing GL, the N value at this level is good and hence the

calculation of Sbc at this level yields as 200kN/m2. The design of foundation was done

adopting a sbc of 200kN/m2

and the DPR was submitted to Executive Engineer. On

scrutiny of the same, he doubted bout the adoption of Sbc and the joint site visit with

Exe. Engineer, Asst. Exe. Engineer and the Consultant decided to do a soil investigation

at the proposed plot. The Geotechnical investigation is carried out by the Consultant

itself and the results were co ordinate from Mar Athanasius College of Engineering.


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STRUCTURAL SYSTEM

The whole structure is analyzed as closed column beam frame in ETABS analysis

software and the design of various structural elements done manually.

Load transfer path is slab-beam-column-footing to soil.

Design parameters

Design loads

Dead loads

The dead loads are in accordance with IS 875 Part 1 (1987).

For the calculation of dead load acting over beams at various levels the unit

weight of the building materials are taken according to that given in IS 875 Part -I-Dead

weight of building materials. For calculating the live load acting over various floor levels

IS 875 Part II is referred. All the loads are given according to the data given in the floor

plans and cross sections given. The self weight of the structure is taken by the software

itself.

The unit weight of hollow brick masonry is taken as =20 kN/m3

The unit weight of concrete is taken as =25 kN/m3

Weight of brick wall = 0.20 x 3.3x 20 = 13.20kN/m

Wt of floor finish = 1.0 kN/m2

Self Wt of floor slab (12cm Thick) = 3 kN/m2

Load considered for water tank = 15 kN/m2

Live loads

The live loads are in accordance with IS 875 Part 2 (1987).

type Live load (kN/m2)

Wards, Nursing

stations2

Operating rooms, X

rays, Scan, store 3


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Stair cases,

Balconies, Corridors,4

OPDs, Offices, 2.5

Laboratories,

laundries, Kitchen3

Earthquake Loads as per IS: 1893 (part 1): 2002

Dynamic forces on multi-storied are best computed through a detailed vibration analysis.

Detailed dynamic analysis or modal analysis or pseudo static analysis should be carried

out depending on the importance of problem. BIS Code 1893 (Part 1): 2002 recommends

that [Ref: Cl: 7:8:1]

Dynamic analysis shall be performed to obtain the design seismic force, and its

distribution to different levels along the height of the building and to the various lateral

load-resisting elements for the following buildings:

a) Regular buildings those greater than 40m in height in Zone IV

and Zone V, and those greater than 90m in height in Zone II and

Zone III.b) Irregular buildingall framed buildings higher than 12m in Zones

IV and Zone V, and those greater than 40m in height in Zone II and

III.

Since the height of the residential complex is 44.35m and its located in Zone III, static

method of analysis was performed to find the seismic load and its distribution.

Static method:

The base shear or total design lateral force along any principal direction shall be

determined by the following expression:

VB= AhW

where,

VB = The design base shear

Ah = Design horizontal acceleration spectrum value using the fundamental natural

period T


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W= Seismic weight of the building.

The design horizontal seismic coefficientgR2

SIZ ah A

Where,

Z = Zone factor given in table 2, for the Maximum Considered Earthquake (MCE)

and service life of structure in a zone. The factor 2 in the denominator of Z is

used so as to reduce the MCE zone factor to the factor for Design Basis

Earthquake (DBE)

I = Importance factor, depending upon the functional use of structures,

characterized by hazardous consequences of failure, post-earthquake

functional needs, historical value or economic importance (Table 6 IS 1893

(Part 1):2002

R = Response reduction factor, depending on the perceived seismic damage

performance of the structure, characterized by ductile or brittle deformations.

However, the ratio (I/R) shall not be greater than 1.0. The values for

buildings are given in Table 7 of IS 1893 (Part 1): 2002.

g

Sa Average response acceleration coefficient.

Distribution of Design Force

The design base shear VB was distributed along the height of the buildings

as per the following expressions.

ni

i

ii

iii

hW

hWVBQ

1

2

2

Where,

iQ = Design lateral force at floori

iW = Seismic weight of floori

ih = Height of floori measured from base.


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n = Number of storeys in the building is the number of levels at which the

masses are located.

Seismic weight, W

The seismic weight of each floor is its full dead load plus appropriate

amount of imposed loads while computing the seismic weight of each floor, the weight of

columns and walls in any storey shall be equally distributed to the floors above and below

the storey. The seismic weight of the whole building is the sum of the seismic weights of

all the floors. Any weight supported in between storey shall be distributed to the floors

above and below in inverse proportion to its distance from the floors.

Imposed uniformly distributed floor

loads kN/m

Percentage of imposed load

%

Upto and including 3.0 25

Above 3.0 50

Table-Percentage of imposed load to be considered in seismic weight calculation

Determination of Design Base Shear for Seismic Analysis:

As per IS 1893 (Part 1):2002

Fundamental natural period, Ta(Clause 7.6.2) = 0.09h/d

h = height of building exclude basement floor = 20.30 m

d- base dimension at plinth level in respective direction=36.6

= 0.50sec

For 0.1


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4.3.6. Calculation of design seismic pressure

Calculation of design seismic pressure

The above parameters are defined in the ETABS software and software itself will

calculate the seismic loads and create the load cases and load combinations. The software

automatically has done the distribution of seismic force.


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STRUCTURAL MATERIALS

Concrete and Reinforcement

Concrete: M25 for Foundations, M30 for Columns, M25 for Beams, Slabs, Stairs,

and all other components

Steel reinforcement:

Fe500 TMT grade pertaining to IS: 1786 1985

Cover:

From durability requirement, environmental exposure condition is assumed as


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The nominal cover to outermost reinforcement shall be as follows for two hour

fire rating.

Columns 40mm

Beams 25mm

Slab 20mm

Stair 25mm

Foundations 50mm

MODELLING AND ANALYSIS METHODOLOGY

BRIEF:

The building is modelled as 3D structure and is analysed as SMRF (Special

Moment Resisting Frames).

The FEM based structural software (ETABS Nonlinear v9.7.2) is used for modeling and

analysis of the building.

MODELLING

The basic approach for using the program is very straight forward. The user

establishes grid lines, defines material and structural properties, places structural

objects relative to the grid lines using point, line and area object tool. All the types of

loads that the structure is subjected can be defined and assigned to the appropriate

structural components. The analysis can be performed and the results are generated in

graphical or tabular form that can be printed to a printer or to a file for use in other

programs. The following topics describe some of the important areas in the modeling.

Defining Material Properties

In the property data area, name of the material, mass per unit volume, weight

per unit volume, modulus of elasticity, Poissons ratio should be specified for each type

of material defined. The mass per unit volume is used in the calculation of self-mass of

the structure. The weight per unit volume is used in calculating the self-weight of the

structure.


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Defining Frame Sections

Frame sections like beams, columns and are defined under this. The sizes of

beams and columns are fixed here and their reinforcement requirements and concrete

covers defined. Hinges were introduced (i.e. end moments were released) near the

connecting where ever required.

Defining Slab Sections

For defining the type of slab section in ETABS, there are three options available

based on its behavior, namely shell type, membrane type and plate type. Shell type

behavior means, both in-plane membrane stiffness and out-of-plane plate bending

stiffness can be provided for the section. Membrane type behavior mean, only in-plane

membrane stiffness is provided for the section. Plate-type behavior means that only out-

of-plane bending stiffness is provided for the section. In the present analysis, slabs are

given membrane type behavior to provide in plane stiffness and shear walls are defined

as shell elements. Shell elements should be divided in to finer mesh so that proper

connectivity is achieved, as our focus is mainly on the global behavior of the in filled

frame structure.

Dead load, live load, roof live load, are defined under the static load case option

of the define menu. Various load combinations can also be defined in the load

combinations option of the define menu.

Member Property Specifications and Support Condition

The dimensions of different members were fixed based on the trial design. The column

dimensions provided for the modeling is as prescribed by the Architect. If necessary it

will revised during the design stage. The beams are provided in such a way that torsion is

released since compatibility torsion alone comes in them. The member properties

assigned are as given below.

Slab

Thickness of the slab = 120mm


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Beams

The dimensions of the beams are as shown below

Beam Breadth, B Depth, D

Fixed Beams 200mm 500mm

Fixed beam 250mm 600mm

Fixed beam 200mm 450mm

Column:

The column dimensions are as follows:

Ground floor: 250mm X 500mm, 300mm X 500mm, 400mm X 400mm, 500mmX 500mm,

(steel as per details)

Staircase:

The staircase is provided as an equivalent slab. The thicknesses of the slab used for

staircase is 175mm

Support condition

Then support conditions were given to the structure. The support condition given was

pinned.

LOAD COMBINATION

The following are the load combinations as IS: 456-2000

1) 1.5 D.L + 1.5 LL

2) 1.5 DL + 1.5 SLX

3) 1.5 DL - 1.5 SLX

4) 1.5 DL + 1.5 SLY

5) 1.5 DL - 1.5 SLX


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6) 0.9 DL + 1.5 SLX

7) 0.9 DL - 1.5 SLX

8) 0.9 DL + 1.5 SLY

9) 0.9 DL - 1.5 SLY

10) 1.2 DL + 1.2LL + 1.2 SLX

11)1.2 DL + 1.2LL - 1.2 SLX

12) 1.2 DL + 1.2LL + 1.2 SLY

13)1.2 DL + 1.2LL - 1.2 SLY

Column Layout


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Completed Model


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Completed Extruded Model


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Completed Extruded Model of Ramp


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DESIGN OF ELEMENTS

Analysis Results

Axial Force on Columns


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Bending Moment Diagram of Beams

Shear Force Diagram of Beams


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Design Methodology:

All structural concrete elements will be designed according to the Limit State

Method as specified in IS: 456 - 2000 for reinforced concrete elements and detailing will

be as per standards.

Design of foundation:

The building foundation was first proposed with column isolated footings based

on the submitted soil report of nearest building. The Sbc recommended by soil expert

was 150kN/m2

1.5m from GL. The Building is proposed with two basements, so the

founding level will be 4m below from existing GL, the N value at this level is good and

hence the calculation of Sbc at this level yields as 200kN/m

2

. The design of foundationwas done adopting a sbc of 200kN/m

2and the DPR was submitted to Executive

Engineer. On scrutiny of the same, he doubted bout the adoption of Sbc and the joint

site visit with Exe. Engineer, Asst. Exe. Engineer and the Consultant decided to do a soil

investigation at the proposed plot. The Geotechnical investigation is carried out by the

Consultant itself and the results were co ordinate from Mar Athanasius College of

Engineering.

Soil Profile

The boreholes, numbered 1,2.3 and 4 were terminated at 29.40

m,29.90m,26.00m and 27.70m respectively. Hard rock was encountered in all the

boreholes. Lateritic clayey silt were found in all the bore holes. Very fine sandy silt, very

fine silty sand and Lateritic clay with sand were found in some of the boreholes ,Hard

rock was fund in all the boreholes,. The N value is found tobe varying from 7 to greater

than 100.

DATA AND DISCUSSION

The bore hole details are given in the attached bore log. The report on the

analysis of the recovered representative samples collected from the boreholes is

attached. Based on visual identification and the laboratory test results using

representative samples, the soil profile at the bore hole location is drawn and are also

presented in borehole logs. For the lateritic clay found in all the bore holes, sand content

3% to9%, silt content varies between 42% and 73% and clay content was between 18%


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between 0.30 kg/cm2 and 0.60 kg/cm2. The N value for these strata was fond to be

between 8 and 21. For the lateritic clayey silt found in all the bore holes, sand content

2% to 15% silt content varies between 72% and 87% and clay content was between 3%

ad 27%. The cohesion was between 0.25 kg/cm2 and 0.70 kg/cm2. The N value for these

strata was found to be between 7 and 45. The very fine sandy silt found in bore holes 1,3

and 4 sand content varies between 15 % to 42% and silt content varies between 55%

and 85%. The N value for these strata was found to be between 23 and greater than 100.

The very fine silty sand found in bore holes 1 and 2 sand content varies between 58% to

68% and silt content varies between 32% and 42%. The N value was found to be greater

than 100. The Lateritic clay with sand found in bore holes 2,3 and 4, sand content varies

between 0% to 21%, silt content varies between 36% and 55% and clay content between

35% and 45%. The N value for these strata was fond to be between 7 and 18. From the

test results for the stratum having N value more than 10 the safe bearing capacity can be

taken as 6.3T/sq.m and for layers having N value 20, it may be taken as 17.2T/sq.m.

RECOMMENDATIONS

The soil at the site mainly consists of Lateritic clay and Lateritic clayey silt. Very

fine sandy silt. Very fine silty sand and Lateritic clay with sand were found in some of the

boreholes. Hard rock was found at all the bore holes. The N value is found to be varying

from 7 to greater than 100.

For the stratum having N value more than 10, the safe bearing capacity can be

taken as 6.3T/sq.m and for layers having N value 20, it may be taken as 17.2T/sq.m.

Depending on the number of floors, the foundation shall be decided. It is suggested to

provide pile foundation which extends to hard rock. Open foundation shall be adopted.

If the load on foundation is not high. She recommendations made in this report are

based on the results of field tests as well as tests done on the samples recovered from

the bore holes. It is presumed that the soil below the maximum depth of exploration at

the site does not vary much or rather improves from that observed at the maximum

depth

Based on this report, the foundation system adopted is Pile Foundation. Since

the capacity is not provided by the Soil Expert, the Consultant Engineer calculated both

geotechnical and Structural Capacity of various dia piles


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Geotechnical Capacity of Piles

450mmDia

500mm dia


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550mm dia

Pile Capacity

Sl No Pile Diameter(mm) Pile Capcity(kN)

1 450 970

2 500 1100

3 550 1300

Design of Pile

450mm Dia Pile

As per IS: 2911

Fixity depth = 8d = 8 x 0.45 = 3.6m

Total No of Pile =134 No.s

Base Shaer( Result from Etabs)= 4354kN

Horizontal Force =32.73kN

Moment due to horizontal force = 117.8kNm


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Factored Moment Mu =176kN-m

For 450mm dia pile; P =970kN

Pu =1445kN

2Df

P

ck

u

= (1445x1000)/ (25x4502)

=0.284

3

6

345025

10176

Df

M

ck

u

=0.077

Providing 40 mm clear cover and assuming 20 mm dia bar

d' =50

D

d1

= 0.106

062.ck

f

P, p = 1.55

pmin= 0.8

Area of longitudinal steel 22403mmAs

This is to be provided up to fixity depth 8d = 3.6m

Hence provide 12 nos of Y16mm dia bars as longitudinal reinforcement

Provide circular links of 8 mm dia at 200 mm c/c spacing.

Provide minimum longitudinal reinforcement as per IS 2911 Part I/ section 2

Minimum area of longitudinal steel = 0.4% of total c/s area

=635 mm2



Provide circular spacers of 12mm dia at 3000mm c/c


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500mm Dia Pile

As per IS: 2911

Fixity depth = 8d = 8 x 0.5 = 4.0 m

Total No of Pile =134 No.s

Base Shaer( Result from Etabs)= 4354kN

Horizontal Force =32.73kN

Moment due to horizontal force = 130.8kNm

Factored Moment Mu =196.38kN-m

For 450mm dia pile; P =1100kN

Pu =1650kN

2Df

P

ck

u

= (1650x1000)/ (25x5002)

=0.264

3

6

3

50025

10196

Df

M

ck

u

=0.062

Providing 40 mm clear cover and assuming 20 mm dia bar

d' =50

D

d1

= 0.10

041.ckf

P, p = 1.01

pmin= 0.8

Area of longitudinal steel 21982mmAs

This is to be provided up to fixity depth 8d = 4m




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Provide minimum longitudinal reinforcement as per IS 2911 Part I/ section 2

Minimum area of longitudinal steel = 0.4% of total c/s area

=785 mm2



Provide circular spacers of 12mm dia at 3000mm c/c

Design of Pile Cap

Two pile group

Material Constants

Concrete,fck = 25 N/mm

Steel, fy = 500 N/mm

Each pile should be connected using pile cap with a minimum of 100mm edge distance to either

sides of the pile. This pile cap is designed as simply supported beam.

As per IS 2911 spacing between two pile is 2.5 x dia of pile

Length of pile cap = 2.5 x 500 + 2 x 250 + 2 x 150

=2050 mm=2050mm

Depth of pile cap = development length of column bar + cover

As per SP-16 Table 65

For 20 mm diameter bars

Ldc = 777 mm

Assume a 100 mm projection of pile in to the cap concrete

Depth of pile cap = 777 + 100

= 877 mm

Provide an overall depth, D = 1000mm

Breadth of pile cap = diameter of pile + 150 mm overhang

= 500 + 2 x 150

= 800mm

Size of pile cap 2.05 x 0.8 x 1.0 m


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Effective depth, d = 900 mm

b =800 mm

Factored axial load on pile Pu = 1650 kN

Bending moment at face of column = 1100 x 0.625

= 656.25 kN-m

Ultimate moment,Mu = 1030 kN-m

Mu / (bd2) = 1.69

% of tension steel, pt = 0.428

Area of tension reinforcement,Ast = 3425mm

Provide reinforcement of Y25mm dia bars 7 Nos

Area of steel provided = 3430 mm


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Hence Maximum shear force on pile cap = 1100kN

Ultimate shear,Vu = 1650 kN

Nominal shear stress, v = 2.4 N/mm

100As/ (bd) = 0.48

Deign shear strength, c = 0.49 N/mm

ie, v > c so shear reinforcement are needed

Assume 12mm dia 6 legged stirrups

Vus =Vu - c bd = 1372 kN

Diameter of bar = 12 mm

Area of shear reinforcement effective in shear,Asv = 678.58 mm

Provide Y12 mm dia 6 legged stirrups

Spacing of shear reinforcement,Sv = 0.87 x d xfyx Asv

Vus


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Design of columns:

Columns are designed by taking the forces and moments from the FEM software.

The sizes of columns are kept constant at all the stories. The design of column is done

considering the axial compression, biaxial bending moment including slenderness effect.

Excel spread sheets are used for designing of columns as per standards. The Columns are

designed for GF+4 floors.

Axial force diagram of typical Column


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ETABS 2013 13.1.3 License #*192TZNDF9YDF4PW

Final Model with Pile.EDB Page 1 of 2 7/16/2014

ETABS 2013 Concrete Frame Design

IS 456:2000 Column Section Design

Column Element Details Type: Ductile Frame (Summary)

Level Element Section ID Combo ID Station Loc Length (mm) LLRF

GF C83 C300X500 DCON7 0 3900 0.594

Section Properties

b (mm) h (mm) dc (mm) Cover (Torsion) (mm)

300 500 50 23.6

Material Properties

E c (MPa) f ck (MPa) Lt.Wt Factor (Unitless) f y (MPa) f ys (MPa)

27386.13 30 1 500 500

Design Code Parameters

C S

1.5 1.15

Axial Force and Biaxial Moment Design For P u , M u2 , M u3

Design P ukN

Design M u2kN-m

Design M u3kN-m

Minimum M 2kN-m

Minimum M 3kN-m

Rebar Area

mm

Rebar %

%

2092.8237 -45.7945 142.2591 41.8565 48.693 3152 2.1

Axial Force and Biaxial Moment Factors

K Factor

Unitless

Length

mm

Initial Moment

kN-m

Additional Moment

kN-m

Minimum Moment

kN-m

Major Bend(M3) 0.831928 3300 57.2852 0 48.693

Minor Bend(M2) 0.704905 3300 -18.3178 0 41.8565


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Shear Design for V u2 , V u3

Shear V ukN

Shear V ckN

Shear V skN

Shear V pkN

Rebar A sv/s

mm/m

Major, Vu2 64.3742 140.4314 54 87.6777 332.53

Minor, V u3 63.1923 133.5314 50 63.1923 554.22

Joint Shear Check/Design

Joint Shear

Force

kN

Shear

V TopkN

Shear

V u,TotkN

Shear

V ckN

Joint

Area

cm

Shear

Ratio

Unitless

Major Shear, V u2 N/A N/A N/A N/A N/A N/A

Minor Shear, V u3 N/A N/A N/A N/A N/A N/A

(1.1) Beam/Column Capacity Ratio

Major Ratio Minor Ratio

N/A N/A

Additional Moment Reduction Factor k (IS 39.7.1.1)

A gcm

A sccm

P uzkN

P bkN

P ukN

k

Unitless

1500 31.5 3207.0354 989.5549 2092.8237 0.502467

Additional Moment (IS 39.7.1)

Consider

M a

Length

Factor

Section

Depth (mm)

KL/Depth

Ratio

KL/Depth

Limit

KL/Depth

Exceeded

M aMoment (kN-m)

Major Bending (M 3 ) No 0.8462 0.5 5.4907 12 No 0

Minor Bending (M 2 ) No 0.8462 0.3 7.754 12 No 0

Notes:

N/A: Not Applicable

N/C: Not Calculated

N/N: Not Needed


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Design of beams

The RC beams and slabs are designed using Excel spreadsheet using the analysis

results from FEM software. The top as well as bottom reinforcement shall consist of at

least two bars throughout the member length.

Bending Moment diagram of typical continuous beam

Shear Force diagram of typical continuous beam


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Design for area of steel and shear for singly reinforced beam by limit state design method

Calculation of Ast req for beams

Ref IS 456-2000 Cl G-1.1b & G-1.1c For sections without compression reinforcement

fy fck b D Cc Cg of bar d Mulim pt lim

N/mm2 N/mm2 mm mm mm mm mm kN.m %

500 25 200 500 25 8 467 145.03 0.94

Mu support Ast req. spt ptreq.spt Mu span Ast span ptreq.span

kNm mm2 % kNm mm % d req mm d prov mm Result

135 802.93 0.86 55 288.73 0.31 450.56 467 okay

Reinforcement details provided at support and span of beam

Nos. dia Ast support pt support Result Nos. dia Ast span pt span

mm mm % mm mm %

2 16 2 16

2 16 2 16

Check for shear in beams (limit state design method)Ref IS 456-2000 Cl 40.1, Cl 40.2.3, Table 19, Table 20 & Cl 40.2.1

fck Vu pt v c c max

prov. Cl 40.1 Table 19 Table 20

N/mm2 kN % N/mm2 N/mm2 N/mm2

25 110 0.86 1.18 0.61 3.1

Design for shear reinforcement (vertical stirrups)

Ref IS 456-2000 Cl 40.4a

Vu cb d Vus Vus/d fy assuming no. stirrup Vus/d prov.

req req stirrup dia of stirrup sp assumed kN/cm

kN kN kN kN/cm N/mm2

mm legs mm Cl 40.4 a

110 56.97 53.03 1.14 415 8 2 100 3.630

Check for minimum and maximum spacing of stirrup

Min stirrup Max stirrup stirrup Result

spacing mm spacing mm sp prov.

Cl 26.5.1.6 Cl 26.5.1.5 mm

546.64 300 100 Hence ok

Side face reinforcement

Ref IS 456-2000 Cl 26.5.1.3

b D side face spc b/w

of reinf. bars not to

web req. / face no. dia of Ast prov. exceedmm mm Cl 26.5.1.3 per face bar mm Cl 26.5.1.3

200 500 not req 2 12 226.19 200 mm

Check for span to depth ratio

Ref IS 456-2000 Cl 23.2.1

Type of fy span d pt req. pt prov. pc MFt MFc

beam N/mm2 mm mm % % %

Cont.Beam 500 5250 467 0.31 0.86 0 1.924 1

l/d l/d Result

prov Cl 23.2.1 Cl 23.2.1

11.24 50.02 Okay

okay 804.25 0.86

tau_v tau_c,design for shear


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Design of slab

Design of slab

Material Constants:

Concrete,fck= 25 N/mm

Steel, fy = 500 N/mm

Loads:

Using 120 mm thick slab

Dead Load on Slab = 0.12 x 25 = 3 kN/m

Live Load on Slab = 3kN/m

Finishes = 1.5 kN/m

Partition load = 2.5 kN/m

Total = 10.0 kN/m

Boundary Conditions one long edge discontinuous

Assume a clear cover of 20 mm & 8 mm dia bars

Eff: depth along shorter direction dx = 96 mm

Eff: depth along longer direction dy = 88 mm

Effective span as per IS 456: 2000 clause 22.2.b

lyeff= 3.2+0.088 = 3.288 m

lxeff= 3.9+0.096 = 3.996 m

lyeff/lxeff =1.22, Hence design as Two Way Slab.


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1 Design for area of steel and shear for two way slab by limit state design method

Slab Geometry

Lx Ly Ly/Lx

m m

3.2 3.9 1.219


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Calculation of Ast req for slab spanning Ly

Ref IS 456-2000 Cl G-1.1b & G-1.1c

- Muy cont. Ast min pt req.cont. + Muy span Ast min pt req.span

kNm mm2 % kNm mm %

4.26 144.00 0.16 3.23 144.00 0.16

Reinforcement details provided at support and span of slab spanning Ly

dia prov. spacing Ast cont. pt cont. Result dia prov. spacing Ast span pt span

mm mm mm % mm mm mm %

8 150 8 150

0 250 0 250

Check for shear in solid slabs for limit state design method

Ref IS 456-2000 Cl 40.1, Cl 40.2.3, Table 19, Table 20 & Cl 40.2.1.1

fck Vu b D clear cg d

N/mm kN mm of slab mm cover mm of bar mm mm

25 21.6 1000 120 20 4 96

pt v k c c max

Cl 40.1 Cl 40.2.1.1 Table 20

% N/mm N/mm N/mm

0.35 0.23 0.55 3.1

Check for span to depth ratio

Ref IS 456-2000 Cl 23.2.1

Type of fy span d pt req. pt prov. pc MFt MFcbeam N/mm

2 mm mm % % %

Cont.slab 500 3200 96 0.15 0.35 0 2.936 1

l/d l/d Result

prov Cl 23.2.1 Cl 23.2.1

33.33 76.34 Okay

Result

tau_v < k tau_c, Ok

tau_v


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DESIGN OF DOG LEGGED STAIRCASE

Data

Internal Dimensions

Length = 4.76 m

Width = 2.6 m

Floor Height = 3.9 m

Fck = 25 N/mm

Fy = 500 N/mm

Riser = 160 mm

Tread = 280 mm

Landing width = 1200 mm

Effective Span = 4.8 m

Height of each flight = 1.95 m

No. of risers in each flight 12.1875 Nos

No. of Tread in each flight 11.1875 Nos

Design

d = 152 mm Required

D = 175 mm

d = 154 mm

Loads

= .

DL on horizontal area = 5.04 kN/m

DL of steps = 2 kN/m

LL = 5 kN/m

FF = 1.5 kN/m

Total load = 13.54 kN/m

Factored load = 20.3 (of one flight)

BM and SF

Mu = 58 kN-m

Vu = 49 kN

d from BM consideration 146 mm

k = 2.466

pt = 0.652 %

Ast = 1005 mm

Main Reinforcement

Dia = 12 mm

Spacing = 112 mm

Distr ibut ion Steel

Ast = 185 mm

Dia of bar = 8 mm

Spacing = 270 mm

Development Length


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Floor Beam

4760

mm

DOWN UP

1200 mm

Mid Landing Beam

2600

mm

Ld = 590 mm

300

mm

Y8 @ 270 mm C/C (Distribution Reinforceme

Y12@112 mm C/C

(Main Reinforcement)

175 mm

175 mm

DETAILING


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ETABS 2013 Shear Wall Design

IS 456:2000 Pier Design

Pier Details

Story ID Pier ID Centroid X (mm) Centroid Y (mm) Length (mm) Thickness (mm) LLRF

TF P4 8115.5 10950.9 4556.7 250 0.426

Material Properties

E c (MPa) f ck (MPa) Lt.Wt Factor (Unitless) f y (MPa) f ys (MPa)

25000 25 1 500 500

Design Code Parameters

S C IP MAX IP MIN P MAX

1.15 1.5 0.02 0.0025 0.8

Pier Leg Location, Length and Thickness

StationLocation

ID Left X 1mm

Left Y 1mm

Right X 2mm

Right Y 2mm

Lengthmm

Thicknessmm

Top Leg 1 7650 11130 9700 11130 2050 250

Top Leg 2 9700 11130 9700 11886.7 756.7 250

Top Leg 3 5900 10500 7650 10500 1750 250

Bottom Leg 1 7650 11130 9700 11130 2050 250

Bottom Leg 2 9700 11130 9700 11886.7 756.7 250

Bottom Leg 3 5900 10500 7650 10500 1750 250

Flexural Design for P u, M u2 and M u3

Station

Location

Required

Rebar Area (mm)

Required

Reinf Ratio

Current

Reinf Ratio

Flexural

Combo

P ukN

M u2kN-m

M u3kN-m

Pier A gmm

Top 2848 0.0025 0.0037 DWAL14 784.892 139.749 275.88 1139166

Bottom 5457 0.0048 0.0037 DWAL12 635.1675 -660.8535 -3663.8173 1139166

Shear Design

Station

Location

ID Rebar

mm/m

Shear Combo P ukN

M ukN-m

V ukN

V ckN

V c + V skN

Top Leg 1 OS DWAL12 430.2772 1013.9719 -1311.7222 130.8789 500.7702

Top Leg 2 1018.78 DWAL7 297.3436 -172.3923 272.992 50.4431 272.992

Top Leg 3 OS DWAL11 493.7266 -892.7358 1127.576 115.2453 431.0062

Bottom Leg 1 OS DWAL12 72.6428 -1121.5661 -1314.807 147.0513 516.9426

Bottom Leg 2 861.61 DWAL9 167.9797 189.7462 238.6595 50.4431 238.6595

Bottom Leg 3 OS DWAL12 878.7701 -880.6772 -1092.6488 153.1835 468.9444

Number of legs where shear force exceeds max allowed (top, bottom) = 2, 2


40/45

DETAILING

All the structural elements were detailed according to IS 456:2000 and SP34.

Detailed drawings were prepared in AutoCAD 2007. Detailing of all the structural

elements were done based on SP 34 and IS 13920


41/45

COLUMN DETAILS

Special confining reinforcement as per is 13920:1993

Special confining reinforcement shall be provided over a length lo from each joint face,

towards midspan, and on either side of any section, where flexural yielding may occur

under the effect of earthquake forces

The length lo shall not be less than

(a) Larger lateral dimension of the member at

Section where yielding occurs,

(b) 1/6 of Clear span of the member, and

(c) 450 mm.

The spacing of hoops used as special confining reinforcement shall not exceed 1/4 of

minimum member dimension but need not be less than 75 mm nor more than 100 mm.


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BEAM DETAILING

Different things which are to be detailed in Beam Detailing is shown below vide sp 34,

page 108

SLAB DETAILING

Different things which are to be detailed in Slab Detailing is shown below vide sp 34,

page 127


43/45

Design of Retaining Wall

Height of Earth Filling =3.6m

Thickness of Wall Assumed =200mm

Unit weight of Soil = 17kN/m3

Surcharge Pressure = 5kN/m2

Co efficient of Active Earth Pressure =0.33

Earth pressure (Kah) =25kN/m2taperded to top to a Value 0 kN/m2

Analysis

The building is having two basements so the retaining wall is inevitable at basement 1and 2. An

internal retaining wall is proposed to separate basement2 and basement 1. The retaining wall is

supported on grade beams, building columns and slabs at top. Hence it is acting as a retaining

slab supported on four sides which effectively reducing the design complications. Another

retaining wall is proposed to retain the external earth forming the road. This retaining wall is

supported on beams at bottom, vertically restrained columns. The top of retaining wall is fixed to

lateral beams connecting vertical columns. This retaining wall is supported on columns

supported on cantilevered grade beams. The analysis is done with building frame in Etabs

software, the results were extracted to design the same.


44/45

Moments in Plate

Maximum Vertical Moment Mx = 50kNm

Moments in Plate

Maximum Horizontal Moment Mx = 30kNm


45/45

Depth of Section

Effective Depth dreq =Mu/ (0.138fckb)

d= 147.5mm,

Provided d =175mm with an overall depth of 200mm. hence okay.

Design for Vertical Moment

Mx = 50 kNm

Factored Moment = 75kNm

Mu/(bd2) = 2.45and

Pt =0.648

Hence provide reinforcement as T 12 @ 100mm C/C as Vertical.

Design for Horizontal Moment

Mx =30 kNm

Factored Moment = 45kNm

Mu/(bd2) = 1.50and

Pt =0.648

Hence provide reinforcement as T 12 @ 150mm C/C as Vertical.

Design for Shear

Vu =45 kN

Factored Shear Force Vu= 67.5kN

Nominal shear stress,v = Vu/bd

= 0.385

From IS 456,

Design shear stressc = 0.60

v

Documents

Structural Analysis Report of RCC Building