ETABS Building Structure Analysis and Design Report

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1. INTRODUCTION 1.1. Problem Statement

Analyse and design an economical and stable RCC framed building for the usage in Residential

purpose using CSI-ETABS and manual calculations.

1.2. Scope

The main scope of this project is to apply standards of Nepal National building codes and IS- 456,

IS-13920, IS-1893 in designing a building. These building require great extent consideration of

earthquake effects on building. This building is located in seismic zone V therefore the lateral

loading of earthquake considered is predominant to the effects of wind loads. Hence wind loads are

not considered. Almost materials and their sizes are so chooses that these are easily available in the

market.

1.3 General

This report summarizes the structural analysis and design of building of .. at . Municipality/VDC ward no..It has planned to utilize the building as educational aspect. The aim of design is the achievement of an acceptable probability that

structures being designed will perform satisfactorily during their intended life.

1. The building will be used dwellings or hotels so that there are Partition walls inside the building.

External walls 230 mm thick and internal walls 115mm thick with 12 mm plaster on both sides are

considered. For simplicity in analysis, no sloping shades are used in the building analysis even though

balconies and terraces are intentionally included.

2. At ground floor, slabs are not provided and the floor will directly rest on ground. Therefore,

only ground beams passing through columns are provided as tie beams. The floor beams are

thus absent in the ground floor.

3. The main beams rest centrally on columns to avoid local eccentricity.

4. For all structural elements except slabs, M25 grade concrete will be used. However, higher M30

grade

concrete is used for central columns up to plinth, in ground floor and in the first floor.

5. Column size are kept in similar group to ascertain simplicity in construction.

6. The floor diaphragms are assumed to be rigid 7. Preliminary sizes of structural components are assumed by experience.

8. Tie Beams are provided in connecting the footings. This is optional in zones II and III; however, it is

mandatory in zones IV and V.

9. Seismic loads will be considered acting in the horizontal direction (along the two principal

directions) and not along the vertical direction, since it is not considered to be significant.

10. The analysis and design has been based on the prevailing codes that are in practice in India

and Nepal, the Indian Standard code IS 1893(Part 1):2002 and the NBC (105:1994) code at places

if required. This report consists of the design procedures adopted, the assumptions made, the

inputs made in the design and the design output.

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11. As per IS 1893(Part 1):2002, the seismic zoning of Nepal can be taken as ZONE IV and ZONE

V , most severe zone of India. For our case, we take the site lies on Zone V. Hence the building is

designed with great consideration towards earthquake resistant practices.

12. All dimensions are in mm, unless specified otherwise

1.4 Building Configuration and Features

The arrangements of Beams, Columns, Balcony slabs, T/B slabs, Room floors are done according as

the figures shown below. Storey height for all floors is taken as 3200mm. The numbering of beams and

columns are presented in Annex I

Building Type : Residential Building of ..

Located at .

Structural system : RCC Space frame, ductile moment resisting frame with infill wall

Plinth area covered : .

Column : Square size 300x300mm

Rectangular size (Main beams) :230 x 355 mm

Slab : 125 mm thick two way slab

Type of foundation : Isolated footing with STRAP BEAM for footing

No. of Storey : Three story including stair cover

Total Height : 9.6 with stair case cover

Wall : 250 mm & 125mm thick brick masonry (1:5 C/S ratio)

Probable Partition : (Actual Partition walls are not considered but 1KN/m2 equivalent

Dead Load is assumed for possible partition)

Type of Sub-Soil : II (Medium type as per NBC 105)

Bearing Capacity of soil adopted = 200 KN/m2 as per site condition.

1.5 Loads on Buildings

1.5.1 Dead Load: A constant load in a building structure that is due to the weight of the members, the

supported structure, and permanent attachments or accessories. This analysis deals with dead loads to

be assumed in the design of buildings and same is given in the-form of unit weight of

materials. The unit weight of other materials that are likely to be stored in a building should be

also included for the purpose of load calculations due to stored materials. These loads are

calculated as specified in IS875-1987(part I)

1.5.2 Live Load : The load assumed to be produced by the intended use or occupancy of a building, including the weight of movable partitions, distributed, concentrated loads, load due to impact and

vibration, and dust load but excluding wind, seismic, snow and other loads due to temperature changes,

creep, shrinkage, differential settlement, etc. This analysis covers imposed loads*(live loads) to be

assumed in the design of buildings. The imposed loads, used in this building analysis, are minimum

loads which should be taken into consideration for the purpose of structural safety of buildings. These

loads are calculated as specified in IS875-1987 (part II)

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1.5.3 Seismic Load: The force on a structure caused by acceleration induced on its mass by an

earthquake. This load is included in design to determine the extent of seismic reinforcing. The

seismic loads on the structure during an earthquake result from inertia forces which were created by

ground accelerations. The magnitude of these loads is a function of the following factors: mass of

the building, the dynamic properties of the building, the intensity, duration, and frequency content

of the ground motion, and soil-structure interaction. The analysis method and earthquake loads

are calculated as specified in IS1893-2002.

1.5.4 Wind Load: Wind is air in motion relative to the surface of the earth. The primary cause of wind is traced to earths rotation and differences in terrestrial radiation. The radiation effects are primarily responsible for convection either upwards or downwards. The wind generally blows horizontal to the

ground at high wind speeds. Since vertical components of atmospheric motion are relatively small, the

term wind denotes almost exclusively the horizontal wind, vertical winds are always identified as such. Wind load on the building would be usually uplift force perpendicular to the roof due to suction

effect of the wind blowing over the roof. The positive or negative force of the wind acting on the

structure; wind applies a positive pressure on the windward side of the building and a negative suction

to the leeward side.. This analysis ignored the wind loads as the building is located in seismic zone V

and hence the earthquake loads predominant it and the height of the building is less.

2. METHODOLOGY

The project provided to us is completed performing each section works mentioned in the contents

before The following stages are involved in the analysis and design of three and half storey

building.

2.1 Load Calculation

Load calculation is done using the IS 1893:2002 and NBC105: 1994 as code of standards. The

exact value of unit weights of the materials from the code is used in the calculation. The thickness

of materials is taken as per design requirements.

2.2 Preliminary Design

The tentative size of structural elements are determined through the preliminary design so

that after analysis the pre assumed dimensions might not deviated considerably , thus

making the final design both safe and economical . Tentative sizes of various elements

have been determined as follows:

2.2.1 Slab

For slab, preliminary design is done according to deflection criteria span /effective depth =

26*modification factor.( IS456-2000 Art 23.2.1)

2.2.2 Beam

Thumb rule of d=L/12 to L/15 basis is adopted to consider the preliminary design of the

beam section .

b/D=1/2

2.2.3 Column

Preliminary design of column is done consideration and interior column. For the load acting in the

column, live load is decreased according to IS456-2000 & SP 16. Cross-sections of the columns

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are adopted considering the economy. Square column section is adopted in this building project as

per the internal aesthetic requirements.

2.2.4 Staircase

Stairs is designed as per drawing. Coolum for stairs boxes is not included in the grid

system but they are assumed to be simply tied with main frame with beam.

2.3 Loading Patterns

Loading pattern from slab to beam is obtained by drawing 450 offset lines from each corners then

obtained trapezoidal as well as the triangular loading and is converted into the equivalent UDL as

described in the respective sections .The loading from cantilever slab part is converted to UDL

acting in beam by dividing the total load by beam. Load from all cantilever part is converted to

UDL acting in beam by dividing total load (wall UDL*total wall length) by length of the beam.

Self-weight of the projected beam

2.4. Gravity Load Calculation

There are three types of loads for which the provided proposed project is designed:

Dead load

Live load

Seismic load

Dead load consists of the load from each element of building i.e. weight of column, beam, slab and

wall. Dimensions of column, beam, and slab are taken from preliminary design and Corresponding

density from code. For wall load thickness of wall is taken from plan. Live load is taken from

relevant code. In case of different live loads in one panel of slab, highest value of load is taken for

the panel. For seismic load whole mass lump of building is calculated from which base shear is

obtained according to code.

2.5 Tools for Analysis

For analysis, different softwares are available during these days. Concerning to the project CSI-ETABS V-15 integrated building software is used for analysis of frames. Manual analysis and design using IS456:2000 carried out for the slabs and foundations with the help of me created

excel-templates made accordingly.

2.6 Design Method

Limit State Method

It uses the concept of probability and based on the application of method of statistics to the

variation that occurs in practice in the loads acting on the structures or in the strength of material.

The structures may reach a condition at which it becomes unfit for use for one of many reasons e.g.

collapse, excessive deflection, cracking, etc. and each of this condition is referred to a limit state

condition. The aim of limit state design is to achieve an acceptable probability that a structure will

not become unserviceable in its lifetime for the use for which it has been intended i. e it will not

reach a limit state. It means structures should be able to withstand safely all loads that are liable to

act on it throughout its life and it would satisfy the limitations of deflection and cracking. We

adopt limit state method for design.

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3. FRAME DESIGN

3.1 ETABS Analysis

3.1.1 Assignments Materials

Table 1 - Material Properties Concrete

Concrete

Grade

E

G Unit

Weight Fc

Lightweight?

MPa 1/C MPa kN/m MPa

M20 20 0.2 5.50E-06 9316.95 25 20 No

Table 2 - Material Properties - Rebar

Name E

Unit

Weight Unit Mass Fy Fu

MPa 1/C kN/m kN-s/m MPa MPa

HYSD415 200000 1.17E-05 76.9729 7.849 415 485

Table 3 - Reinforcing Bar Sizes

Name Diameter Area

mm mm

8 8 50

12 12 113

16 16 201

Loads

The following considerations are made for the assignment of loads on the structural model:

The loads distributed over the area are imposed on area element and that distributed over length are

imposed on line element whenever possible.

Where such loading is not applicable, equivalent conversion to different loading distribution is carried

to load the model near the real case as far as possible.

The imposed loading of infill walls are considered(as per architectural drwg.) as equivalent UDL with

25% to 30% deductions for openings, but the actual modelling of infill walls as equivalent Struts are

not performed. Hence the stiffness of infill walls are not considered.

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The Plinth Tie Beams are designed as purely tie members for lateral loads only, not designed as

flexural members as floor beams.

For simplicity of Structural analysis, Modelling of stair case is not performed & no landing beam is

considered. The DL & LL load of stair case is transferred to the floor beam as equivalent UDL.

Load Patterns

Table 4 - Load Patterns

Name Type Self-Weight Multiplier Auto Load

Dead Load Dead 1

Live Load Live 0

Seismic Load(X) Seismic 0 IS1893 2002

Seismic Load(Y) Seismic 0 IS1893 2002

Load cases

Name Stiffness From Mass Source Load Type Load Name Scale Factor Design Load Type

Dead Preset P-delta MsSrc1 Load Pattern Dead 1 Program Determined

Live Preset P-delta MsSrc1 Load Pattern Live 1 Program Determined

EQX Preset P-delta MsSrc1 Load Pattern EQX 1 Program Determined

EQY Preset P-delta MsSrc1 Load Pattern EQY 1 Program Determined

Dead loads (DL)

Assessment of unit Dead loads

Table 7 Assessment of unit Live Loads

Unit Weight of Concrete = 25 KN/m3 Unit Weight of Brickwork with

Plaster = 20 KN/m3 Unit Weight of Floor Finish 20 KN/m3 Probable Partition Equivqlent Dead

Load = 1 KN/m2 Beam-1 Width = 230 mm, Beam-2 Width = 230 mm,

Beam-1 Depth = 355 mm, Beam-2 Depth = 355 mm, Height Of wall = 3200 mm

Width Of External Wall = 250 mm

Slab Thickness = 150 mm,

Width Of Internal Wall = 135 mm

Floor Finish Thickness = 50 mm,

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Percentage of Opening on wall = 30 %

Stair Area = 10.6 m2

Loads on Beams supporting Two- ways Slabs:

In case of Beams supporting two-way slabs, the load distribution is trapezoidal on long beams and

triangular on short beams with base angle of 45 as shown in fig. The ordinates of trapezoidal and

triangular loads=qLx/2.

Fig:1 Two-way slab Loading

Applications of loads on model

Table 6 Applications of loads on model

a) Beams subjected to External Wall

Dead Load = 11 KN/m

b) Line along the brick masonry partition walls

Dead Load = 6 KN/m

c) StairCase Beam ( Beam-2)

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Length = 2743 mm

Self Weight DL = 2 KN/m

Dead Load from Stair = 9 KN/m (considering one-way spanning of slab)

Dead Load from Wall = 11 KN/m

Live Load from Stair = 12 KN/m

Additional Dead Load= 20 KN/m (other than self-wt. load.i.e.applied on model)

Additional Live Load= 12 KN/m (due to Live load on stair.i.e.applied on model)

d) Floor Slab

Self-Weight DL = 3.75 KN/m2

Furnishing DL = 1 KN/m2

Possible Partition DL = 1 KN/m2

Total Additional Dead Load= 2.00 KN/m2 (other than self-wt. load.i.e.applied on model)

Imposed Load (LL) The imposed loads on the structural system are taken from IS 875(part2)-1987 for

Residential/Commercial building

Assessment of unit Live Loads

Table 7 Assessment of unit Live Loads

Type of Building = Residential

(IS875(II)-1987; Table 1) Clause 3.1

Corridor = 3 KN/m2

Stair = 3

BedRoom = 2

Toilet/BathRoom = 2

Balcony = 3

Roof = 1.5

Terrace =

Note-1: While applying the loads on structural model rounding values are used for simplicity

Note-2: Point load consideration is ignored as the slab has sufficient rigidity to spread the

concentrated load; IS875 (II) Clause 3.1

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Lateral Load Calculation (Earthquake Load)

According to NBC105:1994 & IS 1823-2002, Chitwan lies on the zone 2, V. Hence, the effect of

the earthquake is predominant than the wind load. So, the frame is analysed for the EQ as lateral

load. Among the methods of seismic analysis Seismic Coefficient Method defined in clause 10.1

NBC 105:1994 and equivalent IS 1893-2002 clauses 6.4.2 is used to calculate seismic

coefficient. And hence lateral loads are determined

Assessment of Seismic Loading

Auto Seismic Loading

Table - Auto Seismic - IS 1893:2002 (Part 1 of 2)

Load

Pattern Type

Directio

n

Eccentri

city

%

Ecc.

Overridd

en

Period

Method

Ct

m

Top

Story

Bottom

Story Z Type Z

Soil

Type I

EQX Seismic X + Ecc. Y 5 No Program

Calculated StairCover Base Per Code 0.36 II 1

EQX Seismic X - Ecc. Y 5 No Program


EQY Seismic Y + Ecc. X 5 No Program


EQY Seismic Y - Ecc. X 5 No Program


Table - Auto Seismic - IS 1893:2002 (Part 2 of 2)

R

Period

Used

sec

Coeff

Used

Weight

Used

kN

Base

Shear

kN

4 1 0.0612 1145.9946 70.1349

4 1 0.0612 1145.9946 70.1349

4 1 0.0612 1145.9946 70.1349

4 1 0.0612 1145.9946 70.1349

15/04/2015

Page 10 of 34

IS1893 2002 Auto Seismic Load Calculation

This calculation presents the automatically generated lateral seismic loads for load pattern EQX according to

IS1893 2002, as calculated by ETABS.

Direction and Eccentricity

Direction = Multiple

Eccentricity Ratio = 5% for all diaphragms

Structural Period

Period Calculation Method = Program Calculated

Factors and Coefficients

Seismic Zone Factor, Z [IS Table 2]

Response Reduction Factor, R [IS Table 7]

Importance Factor, I [IS Table 6]

Site Type [IS Table 1] = II

Seismic Response

Spectral Acceleration Coefficient, Sa /g [IS

6.4.5]

Equivalent Lateral Forces

Seismic Coefficient, Ah [IS 6.4.2]

Calculated Base Shear

Direction

Period

Used

(sec)

W

(kN)

Vb

(kN)

X + Ecc. Y 1 1145.9946 70.1349

X - Ecc. Y 1 1145.9946 70.1349

Applied Story Forces

15/04/2015

Page 11 of 34

Story Elevation X-Dir Y-Dir

m kN kN

StairCover 9.144 14.9102 0

Second

Floor 6.096 43.542 0

First Floor 3.048 11.6826 0

Base 0 0 0

15/04/2015

Page 12 of 34

IS1893 2002 Auto Seismic Load Calculation

This calculation presents the automatically generated lateral seismic loads for load pattern EQY according to

IS1893 2002, as calculated by ETABS.

Direction and Eccentricity

Direction = Multiple

Eccentricity Ratio = 5% for all diaphragms

Structural Period

Period Calculation Method = Program Calculated

Factors and Coefficients

Seismic Zone Factor, Z [IS Table 2]

Response Reduction Factor, R [IS Table 7]

Importance Factor, I [IS Table 6]

Site Type [IS Table 1] = II

Seismic Response

Spectral Acceleration Coefficient, Sa /g [IS

6.4.5]

Equivalent Lateral Forces

Seismic Coefficient, Ah [IS 6.4.2]

Calculated Base Shear

Direction

Period

Used

(sec)

W

(kN)

Vb

(kN)

Y + Ecc. X 1 1145.9946 70.1349

Y - Ecc. X 1 1145.9946 70.1349

Applied Story Forces

15/04/2015

Page 13 of 34

Story Elevation X-Dir Y-Dir

m kN kN

StairCover 9.144 0 14.9102

Second

Floor 6.096 0 43.542

First Floor 3.048 0 11.6826

Base 0 0 0

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Load Combinations

The load combinations are based on NBC105:1994, clause 4.4 for Limit state design method.

The following load combinations are used during analysis.

Table 9- Load Combinations

S.N

. Name

Load

Case/Combo Scale Factor Type Auto

1 1.Combo1.5(DL+LL) Dead 1.5 Linear Add No

Live 1.5 No

2 5.Combo (DL+1.3 LL-1.25EQY) Dead 1 Linear Add No

Live 1.3 No

EQY -1.25 No

3 6.Combo (0.9DL+1.25EQX) Dead 0.9 Linear Add No

EQX 1.25 No

4 7.Combo (0.9DL-1.25EQX) Dead 0.9 Linear Add No

EQX -1.25 No

5 8.Combo (0.9DL+1.25EQY) Dead 0.9 Linear Add No

EQY 1.25 No

6 9.Combo (0.9DL-1.25EQY) Dead 0.9 Linear Add No

EQY -1.25 No

7 4.Combo (DL+1.3 LL+1.25EQY) Dead 1 Linear Add No

Live 1.3 No

EQY 1.25 No

8 3.Combo (DL+1.3 LL+1.25EQX) Dead 1 Linear Add No

Live 1.3 No

EQX 1.25 No

9 2.Combo (DL+1.3 LL-1.25EQX) Dead 1 Linear Add No

Live 1.3 No

EQX -1.25 No

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Geometry Assignments

Table 10 Geometry Assignments

Story Diaphragms Slab thickness

All Rigid 125 mm

Story Mesh Option Beams/Lines Wall Edges Further Subdivide Max Element Size

mm

All Auto Cookie Cut Yes Yes Yes 300

Other Assignments

1) 100mm2 steel sections is overridden to beam section at top for ductile reinforcement

consideration.

2) Minimum rebar sizes and numbers are overridden

for beam 12mm dia and 4 numbers of bars

for column 16mm dia and 8 number of bars 3) In every floor slabs are interconnected to act as a diaphragm.

3.1.2 Analysis Preparation

Selection of Analysis Sections

Preliminary design is carried out to estimate approximate size of the structural members.

Grid diagram is the basic guiding parameter for analysis (both approximate and exact)

and is presented below.

Slab

For limit state of serviceability (deflection) criteria,

Span / depth ratio < Where

, , ,, are modification factors given by IS 456: 2000 = 26, for continuous slab [IS 456: 2000, CL: 23.2.1(a)] = 1, for span < 10m, [IS 456: 2000, CL: 23.2.1(b)] = 1.24, for pt = 0.5% (assumed) [IS 456: 2000, CL: 23.2.1(c)]

S.

N.

Design

Type Story Section Type Analysis Section

Design

Procedure Design Section

1

Column All*

Concrete

Rectangular COL300*300 (4-16,4-12)

Concrete

Frame

Design COL300*300 (4-16,4-12) 2

Beam All Tie Beams

Concrete

Rectangular BM 230*300

Concrete

Frame

Design BM 230*300

3

Beam All***

Concrete

Rectangular BM 230*355

Concrete

Frame

Design BM 230*400

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= 1, for pt = 0% [IS 456: 2000, CL: 23.2.1(d)] = 1, for rectangular section [IS 456: 2000, CL: 23.2.1(e)]

Take Overall depth (D) = 150 mm Beam

For main beam

Depth of beam = (1 / 13) * Longest span [IS 456: 2000 CL 22.2]

The section of main beam = 230 * 355 mm, 230*400 mm

Column

For main column

d = H/8 to H/10

D= 3200/ (8 to 10)

= 400 mm to 320 mm

Adopt Size of Column

= 350* 350 mm and 400*400 mm

3.1.3Analysis Outputs

Base Reactions

Table Base Reactions and Foundation Groups

S.N. Joint

Label FX FY FZ MX MY

Foundation

Group

kN kN kN kN-m kN-m

1 1 11 9 359 9 15 F2

2 2 11 2 240 14 15 F1

3 3 6 1 420 15 11 F2

4 4 3 2 210 12 8 F1

5 5 2 8 337 9 7 F2

6 6 7 10 610 9 11 F3

7 7 7 5 559 13 11 F3

8 8 2 5 305 11 7 F2

9 9 5 6 665 11 10 F3

10 10 2 6 343 10 6 F2

11 11 5 10 391 8 10 F2

12 12 2 8 196 7 7 F1

13 13 10 8 221 8 14 F1

14 14 12 7 385 11 17 F2

15 15 11 5 326 13 15 F2

Storey Drifts

Table: 12 Storey drift

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Storey Drift ratio for all storied are checked as defined in clause 7.11.2, IS 1893-2002.It is found that

storey drift ratio for all stories are within permissible limit 0.004. OK. All the reaction forces, drifts and

deflections are shown in ANNEX-I

Base Reactions are used to Design Foundation

Sections Forces

Typical analysis forces of beam/column and slab are presented below. All the beam/column

forces are presented in ANNEX-II

Fig:5 Direction of forces in Beam Fig:6 Direction of Forces in Column

Storey Maximum Drift

Stair Cover 0.000789

Second Floor 0.000605

First Floor 0.000521

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Fig:7 Axial Force Diagram in Columns of Elevation B

Fig:8 SFD of First floor Beams in (2-2) of First Floor Beams

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Fig:9 Bending Moment Diagram (3-3) of Elevation A and B

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Fig:10 Resultant Bending Moment (1-1 and 2-2 ) contour in First Floor Slab

3.2 Design Outputs

Preliminary designed sections are provided and the structure is checked for different load

combinations. The detail check and pass of all the message is shown in ANNEX-III

3.2.1 Typical Output of Critical Sections

ETABS 2015 Concrete Frame Design

IS 456:2000 Column Section Design(Envelope)

Column Element Details

Level Element Section ID Length (mm) LLRF

First Floor C7 COL300*300 (4-16,4-12) 3048 0.701

Section Properties

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

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

300 300 56 30

Material Properties

Ec (MPa) fck (MPa) Lt.Wt Factor (Unitless) fy (MPa) fys (MPa)

22360.68 20 1 415 415

Design Code Parameters

C S

1.5 1.15

Longitudinal Check for Pu - Mu2 - Mu3 Interaction

Column End Rebar Area

mm

Rebar

% D/C Ratio

Top 1257 1.4 0.603

Bottom 1257 1.4 0.606

Design Axial Force & Biaxial Moment for Pu - Mu2 - Mu3 Interaction

Column End Design Pu

kN

Design Mu2

kN-m

Design Mu3

kN-m

Station Loc

mm Controlling Combo

kN kN-m kN-m mm

Top 600.9743 7.929 -12.0195 2693 1.5 (DL+LL)

Bottom 610.0605 -4.8085 12.2012 0 1.5 (DL+LL)

Shear Reinforcement for Major Shear, Vu2

Column End Rebar Asv /s

mm/m

Design Vu2

kN

Station Loc


Top 332.53 0.2183 2693 0.9DL-1.25EQY

Bottom 332.53 0.2183 0 0.9DL-1.25EQY

Shear Reinforcement for Minor Shear, Vu3

Column End Rebar Asv /s

mm/m

Design Vu3

kN

Station Loc


Top 332.53 21.706 2693 0.9DL-1.25EQY

Bottom 332.53 21.706 0 0.9DL-1.25EQY

Joint Shear Check/Design

Joint Shear

Ratio

Shear

Vu,Tot

kN

Shear

Vc

kN

Joint

Area

mm

Controlling

Combo

Major(Vu2) 0.507 0 0 0 DL+1.3LL+1.25EQX

Minor(Vu3) 0.507 0 0 0 DL+1.3LL+1.25EQX

Beam/Column Capacity Ratios

1.1(B/C)

Ratio

Column/Beam

Ratio

SumBeamCap

Moments

kN-m

SumColCap

Moments

kN-m

Controlling

Combo

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1.1(B/C)

Ratio

Column/Beam

Ratio

SumBeamCap

Moments

kN-m

SumColCap

Moments

kN-m

Controlling

Combo

Major33 0.653 1.685 0 0 0.9DL-1.25EQY

Minor22 0.432 2.547 0 0 0.9DL-1.25EQY

ETABS 2015 Concrete Frame Design

IS 456:2000 Beam Section Design (Envelope)

Beam Element Details

Level Element Section ID Length (mm) LLRF

First Floor B10 BM230*355 2743.2 1

Section Properties

b (mm) h (mm) bf (mm) ds (mm) dct (mm) dcb (mm)

230 355 230 0 60 60

Material Properties

Ec (MPa) fck (MPa) Lt.Wt Factor (Unitless) fy (MPa) fys (MPa)

22360.68 20 1 413.69 413.69

Design Code Parameters

C S

1.5 1.15

Flexural Reinforcement for Major Axis Moment, Mu3

End-I

Rebar Area

mm

End-I

Rebar

%

Middle

Rebar Area

mm

Middle

Rebar

%

End-J

Rebar Area

mm

End-J

Rebar

%

Top (+2 Axis) 227 0.28 212 0.26 262 0.32

Bot (-2 Axis) 212 0.26 212 0.26 212 0.26

Flexural Design Moment, Mu3

End-I

Design Mu

kN-m

End-I

Station Loc

mm

Middle

Design Mu

kN-m

Middle

Station Loc

mm

End-J

Design Mu

kN-m

End-J

Station Loc

mm

Top (+2 Axis) -5.1633 150 -0.8944 1828.8 -25.512 2593.2

Combo 1.5 (DL+LL) 0.9DL-1.25EQY 1.5 (DL+LL)

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End-I

Design Mu

kN-m

End-I

Station Loc

mm

Middle

Design Mu

kN-m

Middle

Station Loc

mm

End-J

Design Mu

kN-m

End-J

Station Loc

mm

Bot (-2 Axis) 4.3834 532.2 5.4108 1828.8 3.2232 2211

Combo 0.9DL-1.25EQY 0.9DL-1.25EQY 0.9DL-1.25EQY

Shear Reinforcement for Major Shear, Vu2

End-I

Rebar Asv /s

mm/m

Middle

Rebar Asv /s

mm/m

End-J

Rebar Asv /s

mm/m

442.08 378.52 446.36

Design Shear Force for Major Shear, Vu2

End-I

Design Vu

kN

End-I

Station Loc

mm

Middle

Design Vu

kN

Middle

Station Loc

mm

End-J

Design Vu

kN

End-J

Station Loc

mm

47.2187 150 0.0394 1828.8 48.9573 2593.2

DL+1.3LL-1.25EQX DL+1.3LL-1.25EQX DL+1.3LL-1.25EQX

Torsion Reinforcement

Shear

Rebar Asvt /s

mm/m

505.54

Design Torsion Force

Design Tu

kN-m

Station Loc

mm

Design Tu

kN-m

Station Loc

mm

4.386 2593.2 4.386 2593.2

1.5 (DL+LL) 1.5 (DL+LL)

3.1.2 Summary of Design Sections

Column The brief description of column sections is tabulated below. The detailed column section

reinforcements are presented in Column Schedule attached in structural drawing section

of this report

Structural drawings are explained in ANNEX-IV

Table: 12 Column Sizes and Brief Rebar Schedule

Column Sizes Rebar Area Rebar numbers Ties Remarks

mm*mm mm2

1 300*300 8mm ,6-legged ties @

100mm at joint

and @150mm

at middle of

column

Ties spacing explained

here is a general idea

proper spacing is

presented in column

schedule 1257 4-16,4-12

*Spacing is illustrated in structural drawing attached with this report

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**Column Framing Plan and Column Schedule are attached in structural drawing sheets.

Beam All the sizes of beams and their labels and corresponding rebar are tabulated in Beam Rebar

Table attached with this report in structural drawing section (ANNEX-IV). Mainly the adopted

structurally passed sections are tabulated below

Table:13 Types of Adopted Beams and Their Sizes

Beams Width (mm) Depth(mm)

Main Beams 230 355

Staircase stair landing Beams 230 355

Tie Beams 230 230

Cantilever Overhanging Beams 230 230

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4. SLAB DESIGN 4.1 General

Slabs are plate elements forming floors and roofs of buildings and carrying distributed

loads primarily by flexure. A staircase can be considered to be an inclined slab. They

may be supported on walls or beams or in the columns. The beam supporting the slabs

are considered stiff and do have deflections relative small as that compared to the slabs.

The slabs supported on the wall or beams are called edge supported slab. 4.1.1 Types of Slab

Slabs are classified according to the manner of the support

a) One-way Slab spanning in one direction b) Two-way slab spanning in two direction c) Circular slab d) Flat slab e) Ribbed slab

Two-way slabs are analysed and designed for this building

4.1.2 Methodology of slab design

Important information regarding the design of slab according to IS456:2000

1. Slab is designed for 1m wide strip

2. Temperature reinforcement (Ast min) = 0.12% bD for deformed bars along the

transverse direction to the main bars (Cl.26.5.2.1)

3. Cover minimum = 25mm

4. If Ly/Lx < 2, two way slab is designed

Design Steps for two way restrained slab

1. Effective depth (d) is taken from the preliminary design

2. Find out the loading

3. Find out the effective span

Leff = lo+ t

= lo + d whichever is less

4. Bending moment is calculated according to Annex D IS 456:2000

Mux = x * wu * (lx)2 Muy = y * wu * (lx)2 x and y are the bending moment coefficient from table 26 (IS 456: 2000) Mux and Muy are the moments on the strips of unit width spanning lx and ly

respectively.

Lx and ly are the length of shorter span and longer span respectively.

5. Find out the area of the steel

Mu = 0.87 *fy *Ast*(d- (fy*Ast/fck * b))

6. Find out the spacing for the arrangement of steel.

Sv = 1000 * ( / 4 * 2) / Ast 7. Check for development length according to cl. 25.2.1 IS 456:2000

8. Check for deflection according to cl.23.2.1 IS 456:2000

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4.2 Analysis and Design of Two-way slab

Table: 14 Two-way Slab Sizes and Bottom Main Reinforcement

Calculations of sample slab are presented in ANNEX-V

DL

(KN/m2)

LL

(KN/m2)

Lx (Short

Span)_mm

Ly (Long

Span)_mm

fy

(N/mm2) fck Mpa

Overal thickness of

slab (mm)

clear cover

(mm)

S1 5.750 2.000 4000 4700 415 20 125 20 535 10 125 209 8 300 126 8 300

S2 5.750 2.000 3700 4700 415 20 125 20 512 10 125 179 8 300 126 8 300

S3 5.750 2.000 3700 4000 415 20 125 20 416 10 125 142 8 300 126 8 300

S4 5.750 2.000 3000 4000 415 20 125 20 386 10 125 93 8 300 126 8 300

Atx mm2 (mm)

c/c

spa.(mm)

Reinforcements along Long

span (Middle Strip)

Reinforcements along ANY

Span (Column Strip)

Slab

group

Er. Buddhi Sagar Bastola, NEC 7059 'CIVIL' A

Atx mm2 (mm)

c/c

spa(mm) Aty mm2

(mm) c/c spa.

Table : Slab Dimensions and Rebars Positive Moment Side

Client

Reinforcements along short

span (Middle Strip)

Table :

DL

(KN/m2)

LL

(KN/m2)

Lx (Short

Span)_m

m

Ly (Long

Span)_m

m

fy

(N/mm2) fck Mpa

Overal

thickness

of slab

(mm)

clear

cover

(mm)

S1 5.750 2.000 4000 4700 415 20 125 20 614 10 125 286 8 300 126 8 300

S2 5.750 2.000 3700 4700 415 20 125 20 593 10 125 244 8 300 126 8 300

S3 5.750 2.000 3700 4000 415 20 125 20 484 10 125 189 8 300 126 8 300

S4 5.750 2.000 3000 4000 415 20 125 20 440 10 125 124 8 300 126 8 300

Reinforcements along Long

span (Middle Strip)

Reinforcements along ANY

Span (Column Strip)

Slab group

Er. Buddhi Sagar Bastola, NEC 7059 'CIVIL' A

Atx mm2 (mm)

c/c

spa(mm) Aty mm2 (mm) c/c spa. Atx mm2 (mm)

c/c

spa.(m

m)

Slab Dimensions and Rebars

Client

Reinforcements along short

span (Middle Strip)

Negative Moment Side

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5. FOUNDATION DESIGN 5.1 General

Foundation are the structural element that transfer the loads from the building or

individual columns to the earth. The scope of foundation design is to consider the

excessive settlement, rotation, differential settlement and safety against sliding

/overturning of foundation.

5.1.1 Types of Footings

a) Isolated Footing: used for single column and may have square rectangular or circular shapes

b) Strip Footing: Wall footing

c) Combined footing: supports two or more columns

d) Raft/Mat foundation: Support all columns. Used when soil bearing capacity is low

and sum of individual footing area is more than 50% of plinth area.

e) Pile/Well foundations: minimum three piles are capped to support the structures.

Well foundations are used in bridge foundations.

Selection of footings is made from experience but for economical foundations following

factors governs the major.

- Bearing capacity of soil and N-values of SPT - Permissible differential settlement - Soil strata - Type of structures and loadings on them

Here the type of footing adopted is an isolated footing of size .

5.1.2 Bearing Capacity of soil The total load per unit area under the footing must be less than permissible bearing capacity of

the soil. Foundations must be designed to resist vertical loads, horizontal loads and moments.

Typical net bearing capacity of different soil types are described below.

Rock: 3300KN/m2 to 450 KN/m2

Non-cohesive soil: 450 KN/m2 to 100 KN/m2

Cohesive soil: 450 KN/m2 to 50 KN/m2.

Here the safe bearing capacity adopted is a minimum 200KN/m2 for the proposed site.

5.1.3 Depth of Foundation Factors

-Seasonal weather change e.g. erosion and movement of upper soil

-Lateral earth pressure required to resist horizontal loads.

-safe bearing capacity

Minimum depth of foundation = p/ [(1-sin)/ (1+sin)] =angle of repose of soil, p= gross bearing capacity, = density of soil However minimum depth of 500mm is mandatory.

Here the depth of foundation adopted is a minimum of 1 m from the existing ground level.

5.2 Analysis and Design of Foundation

The reaction forces are obtained from ETABS analysis and the corresponding designs are

made manually with the help of EXCEL template following the criterion of IS: 456-2000.

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Here the safe bearing capacity is taken on the basis of categorization of site soil and

peripheral geographical/hydrological features. Experiences with similar soil type and location

as the determination of proper value is out of the scope of this report. The design parameters

are shown in below and corresponding drawing are also attached in structural drawing section

of the architectural report.

Table: 15 Foundation design assignment of forces and output results.

Calculations of major footings are presented in ANNEX-VI

20

200

415

S.N. F-Group # Joint

Labels

FZ MX MY Bar Spacing c/c

kN kN-m kN-m Lx (mm) Ly (mm) Depth

(mm)

(mm) (mm) Bar No

..

1 F1 2,4,12,13 250 14 15 1250 1200 1000 12 200 10 0

2 F2

1,3,5,8,10,

11,14,15 500 15 15 1700 1600 1000 12 200 12 0

3 F3 6,7,9 750 13 11 2100 2000 1000 12 200 20 4

Note: 1.Foundation are grouped so as to make simplicity in construction.

# F-Group(1) = [Fz=0 to 250 KN] ,F-Group(2) = [Fz=250 to 500 KN] ,F-Group(3) = [Fz=500 to 750 KN],F-Group(4) = [Fz=750 to

1000 KN], F-Group(5) = [Fz=1000 to 1250 KN],F-Group(6) = [Fz=1250 to 1500 KN],

2. Minimum dowels of 10 mm bar is provided in each face of column(4 numbers)

3. All footings have 75mm brick/stone soling and 75mm PCC base from where the depth of footings is so defined in this table.

Client

Location

Date

.

.

Cocrete Strength

MPA

Bearing Capacity

of Soil (KN/m2)

Rebar Strength

MPASize of Footings Dowels

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Fig: 11 Joint Labels at footing

6. CONCLUSION

The purpose of this building is mainly residential as well as small scale of commercial with

limited resources. Hence due to high cost of soil investigation actual borehole site

exploration and the determination of bearing capacity of soil is omitted and adopted with

the experience and visual inspection of site and local possibilities. The frame system

analysis is made with an well powered software ETABS V17.Attempts are made to

economise and simplified the construction ensuring earthquake safety and adopting

common materials, common sections, and schedules. Design process is interactive process

of selecting frames and checking for loads considered. Final safe checked and passed

model with possible minimum sizes of frame members and minimum reinforcement is

adopted. However this design is safe against earthquake no doubly, however more iteration

are avoided in selection of members which make a little costly but not more than 10%.

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Foundations and Slabs are designed manually with the help of excel- design templates

made on the basis of IS 456:2000.Client is suggested to employ supervisor in the

construction periods to ensure the quality control of works/materials within a limit. All

necessary calculations; analysis results and design outputs are presented in annexes as a

Adarsha.pdf version of soft copy file.

REFERENCES

Books and Journals

1) Jain, A.K- R.C.C Limit State Design, Nem Chand & Bros, Roorkee, 1990

2) Shah & Kale- R.C.C Design, Macmillan India Limited

3) Ashok k. Jain- Advanced Structural Analysis, Nem Chand & Bros, Roorkee, 1990

4) S.S. Bhavikati-Structural Analysis- II, Vikas Publishing House Pvt. Ltd.

5) V.N. Vazirani- Analysis of Structures-II, Khanna Publishers

6) S. Ramamrutham-Theory of Structures, Dhanpat Rai Publishing Company

7) www.csiamerica.com

8) Bothara,Jitendra Kumar- Protection of educational buildings against earthquake,NSET-Nepal publication

9) Shrestha, Hima -Retrofitting of common Frame structural houses, NSET-Nepal publication

Codes

1) I.S. 456-2000 -Code of Practice for Plain and Reinforced Concrete 2) I S. 456-1978 -Design Aids for Reinforced Concrete ( S.P.-16 ) 3) S.P.34-1987 - Handbook on Concrete Reinforcement and Detailing 4) I S 1893-2003 -Criteria for Earthquake Resistant Design Structure 5) I S 13920-1993 -Ductile Detailing of Reinforced Concrete Structures subjected to

Seismic forces

6) I S 875-1987 -Code of practice for Design Loads for Buildings and Structures Part 1- Dead Loads

Part 2- Imposed Loads

7) NBC 105 :1994- Seismic Design of Building in Nepal

8) NBC 108 :1994- Site Consideration for Seismic Hazards

9) NBC 201 :1994 - Mandatory Rules of Thumb Reinforced Concrete Buildings with Masonry Infill

Tools

CSI-ETABS V.17: The frame analysis and design of this building is made with CSI-ETABS software

choosing the integrated IS codes of standards. The innovative and revolutionary ETABS is the ultimate

integrated software package for the structural analysis and design of buildings. Incorporating 40 years of

continuous research and development, this latest ETABS offers unmatched 3D object based modelling and

visualization tools, blazingly fast linear and nonlinear analytical power, sophisticated and comprehensive

design capabilities for a wide-range of materials, and insightful graphic displays, reports, and schematic

drawings that allow users to quickly and easily decipher and understand analysis and design results. The

entire building structure was analyzed for gravity (including P-Delta analysis), wind, and seismic loadings

utilizing ETABS version 8.4, from Computers and Structures, Inc (CSI). Major success story of software

are shortly explained below.

- ETABS is used in the structural design of the Burj Dubai in the United Arab. The Burj Dubai

Tower is the worlds tallest structure, passing all previous height records. The entire building structure was

analyzed for gravity (including P-Delta analysis), wind, and seismic loadings utilizing ETABS version 8.4,

from Computers and Structures, Inc (CSI).

- ETABS is used in the design of the new Museum for African Art on Fifth Avenue in New York

City

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Microsoft Office Excel Templates: The Design of Foundations and Slabs are made with Excel-Template

prepared by myself. The so prepared design templates are based on IS 456:2000 - Code of Practice for Plain

and Reinforced Concrete

ANNEXES

1. ANNEX-I-Base Reactions and Drifts/Deflection Of Structural Elements (Soft Copy)

2. ANNEX-II-Frame Section Forces (Soft Copy)

3. ANNEX-III-Design Outputs (Soft Copy)

4. ANNEX-IV-Structural Drawings (Soft as well as Hard Copy)

5. ANNEX-V- Calculations of Sample Slabs (Soft Copy)

6. ANNEX-VI-Calculations of Sample Footings (soft Copy)

Er.Buddhi Sagar Bastola NEC CIVIL A 7059

Page 33 of 34

27/03/2015

Page 34 of 34

ETABS Building Structure Analysis and Design Report

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