Analysis Report
Residential Building,
Thalidanchhi – 1, Kageshwori Manohara
Municipality, Kathmandu
Owner: Designed By:
Mrs. Sushila Khadka Er. Samrak Karmacharya
Thalidanchhi-1, Kageshwori,
Kageshwori Manohara Municipality
BACKGROUND
This Building project is located at Kageshwori – 1, Kageshwori Manohara Municipality. This
project comprises planning architectural design, structural design, electrical design and
sanitary design components. The basic aim of the structural design is to build a structure,
which is safe, fulfilling the intended purpose during its estimated life, economical in terms of
initial and maintenance cost, durable and also maintaining a good aesthetic appearance. The
construction of any building consists of three phases: a) Design b) Drawing with proper
detailing and c) construction as per drawing and details. The design of structure consists of
two parts. i) Analysis and ii) Design. At first the preliminary size of various member for
specific structure are fixed and the analysis is carried out. With the result obtained from
analysis, necessary design is carried out. After the completion of the design, drawings are
prepared with all necessary details. The presentation of the design calculation and drawing
should be clear. After completion of the office works which include design and drawing, the
construction of the building is carried out. The effort with which design has been carried out
becomes worthwhile only if the design is translated to a correspondingly high quality
structure.
Nepal lies in seismically active
region in the boundary of the two
colliding tectonic plates – the India
plates and the Tibetan plates.
Records of earthquake are available
in Nepal since 1255AD. Those
records reveal that Nepal has hit by
18 major earthquakes, the 1833 and
1934 earthquakes were the most
destructive ones. And recently, 2015
Gorkha Earthquake is felt by us.
However, it would not be
economically feasible to design the
building so as to ensure that they
remain elastic and damage free
because the occurrence of maximum
earthquakes low say one in 75 years .
Thus it is reliable to design the ductile structure and not to design damage free structure but
non – collapsible structure for minimum destruction in lives and properties. The design
should ensure the structure against stability, strength and serviceability with acceptable levels
of seismic safety.
Thus the seismic design of the building is done and the brief report has been prepared. All the
design data are considered in the detail architectural and structural drawing.
MATERIAL AND SECTIONAL PROPERTIES
MATERIAL PROPERTY
Concrete Grade of concrete M20
Young's Modulus of Elasticity; It is calculated according to the following formula
Ec=5000 𝜎
=5000 √20
= 22360N/mm2
Grade of Steel Fe500
Assuming Damping = 0.05
SECTIONAL PROPERTIES
Moment of Inertia: The beams in the building frames will act as rectangular in the end
portion near the support and will act as T or L beams in the central portion . For the
purpose of analysis, a general practice is to assume the equivalent Moment of Inertia for
the whole length of the beams . The Moment of inertia is calculated for the rectangular
portion and multiplying it by 2.0 for T- beams and 1.5 for L-beams.
Lateral stiffness: The lateral stiffness of the column is calculated using the following formula
12𝐸𝐼
𝐷=
𝑙
LOAD CASES AND COMBINATIONS
Load cases
. Dead load (DL)
. Live load (LL)
. Earthquake load in + ve X – direction (EQX)
. Earthquake load in – ve X – direction (-EQX)
. Earthquake load in + ve Y – direction (EQY)
. Earthquake load in – ve Y – direction (-EQY)
Load combination as per IS 1893:2016
1. COMB1 1.5(DL+LL)
2. COMB2 1.5(DL + EQX/WL)
3. COMB3 1.5(DL – EQX/WL)
4. COMB4 1.5(DL +EQY/WL)
5. COMB5 1.5(DL – EQY/WL)
6. COMB6 0.9DL +1.5EQX/WL
7. COMB7 0.9DL - 1.5EQX/WL
8. COMB8 0.9DL +1.5EQY/WL
9. COMB9 0.9DL - 1.5EQY/WL
10. COMB10 1.2(DL + LL+EQX)
11. COMB11 1.2(DL + LL-EQX)
12. COMB12 1.2(DL + LL+EQY)
13. COMB13 1.2(DL + LL-EQY)
BUILDING PARAMETRS
ARCHITECTURAL AND FUNCTIONAL REQUIREMENTS
Types of building: Residential Building
Types of structural system: Reinforced Concrete Frame
Number of stories 4 storey
Design provision for future extension 0 storey
Story Height 2.84m
Height of parapet wall 1m
Total height of the Building 11.38 m
Least lateral base dimension of the building 9.27 m
External wall/ some internal wall 230 mm
Few internal wall 115 mm
Plaster thickness 15 mm
CONSTRUCTION SITE
Location Kageshwori - 1, Kathmandu
Soil type Type II (stiff clay)
Bearing capacity 150 KN/mm2
DIMENSIONS AND MATERIALS
Slab thickness 125mm
Footing thickness 600mm & 650mm
Tie Beam size (mm) 230 x 300
Beam size (mm) 230 x350
Column size (mm) 300 x 300
CONSTRUCTION MATERIALS
Cement Ordinary Portland cement
Grade of concrete M20
Grade of steel Fe415, Fe500
ASSESSMENT OF UNIT LOADS OF MATERIALS
DENSITY OF MATERIALS
Reinforced concrete 25.0 KN/m3
Plain cement concrete 24.0 KN/m3
Brick masonry 19.2 KN/m3
Rebar 78.5 KN/m3
Light Weight Filling in Sunken area 0.8 KN/m3
Cement mortar / plaster 2.08 KN/m3
Floor finish 1.2 KN/m3
Brick Bat coba for terracing 2 KN/m3
ASSESSMENT OF LIVE LOAD
Unit loads on floor
All Rooms and kitchen 2.0 KN/m2
Toilet and Bathrooms 2.0 KN/m2
Corridors, passage, staircases, Verandas 3.0 KN/m2
Roof (accessible) 1.5 KN/m2
Roof (Non accessible) 0.75 KN/m2
WIND LOADS
Wind and seismic loads shall not be taken to act simultaneously. Kathmandu being high
seismic area, Seismic Forces are expected to govern and hence Wind load have not been
considered in design.
OTHER LOADS
Following effects expected to be insignificant and shall be ignored.
Shrinkage, creep and temperature stresses, excepting special cantilevers.
Erection loads (for usual cast-in-situ framed structure DL+LL shall be more severe).
METHOD OF ANALYSIS
The framing systems (including the sizes of various structural elements) have been worked
out, on the basis of a preliminary structural analysis and also in co-ordination with relevant
architectural & services requirements. Space frame analysis using ETABS software has been
undertaken to obtain refined results for all load combinations in accordance with IS:456-
2000.
Column/Shear walls and Beams have been modeled as line members but additional points
have been taken at beam/column face. The Beam Column Junction is understood to behave as
rigid and therefore each member has been idealized as consisting of three segments. The
central one represents the linear elastic member and the other two end segments that represent
the parts common to beam and column/wall junction as rigid.
Analysis method adopted for EQ resistant design: Seismic coefficient
Total number of design load cases considered: Thirteen
Seismic zoning factor: 1.0
Basic seismic coefficient: 0.08
Important factor: 1.0
Structural performance factor: 1.0
Seismic weight of structure: 4747.45 KN
Horizontal base shear at plinth level: 379.79 KN
Fundamental time period considered: 0.71 sec (software)
Top Storey Deflection: 20.02 mm
Max. Storey Drift: 0.0023
DESIGN PROCEDURE
The RCC design shall be based on provisions laid down in IS:456-2000: Code of practice for
plain and reinforced concrete, following Limit State philosophy. Structural design for typical
members has been done for the combination of loads that produces maximum stress in the
structural elements, and in turn requires maximum reinforcing steel provisions.
The design of Columns and Beams is done directly using ETABS design software. The
design of Slab, Staircase is down by in house developed Worksheets in Excel. Clause 7.1.3 of
IS:13920 states that preferably the proportion of shorter to longer side of a column section
should be not less than 0.4. Similarly, the design of Foundations is done using SAFE design
software.
CALCULATION OF HORIZONTAL BASE SHEAR FORCE:
SEISMIC LOAD CALCULATION:
Calculation of Seismic Weight of Building
Seismic wt. at any floor level = Wi = (total Gravity loads due to beams, slabs, column and
walls for 1/2 ht. above and 1/2 ht. below the level + 50% of Live load)
Calculations of Total Base shear:
Design Seismic Base shear
VB=Ah*W
Where,
Ah = Design Horizontal Seismic Coefficient
W = Seismic Weight of the building
Design Horizontal Seismic Coefficient
Ah = Z/2 * I/R * Sa/g
Where,
Z = Zone Factor = 0.36 as applicable for structures built in Zone V.
I = Importance factor for the building = 1
R = Response Reduction factor = 5
Sa/g = Average Response Acceleration Coeff. is taken for Soil Type-2 and
5% Damping.
DETAIL OF COLUMNS, BEAMS, SLABS AND FOOTINGS
SLAB REINFORCEMENT BARS
SN Type Thickness Reinforcement at short span Reinforcement at Long span
1 Slab 125mm 8mm ф @ 150 mm c/c 8mm ф @150 mm c/c
FOOTING DETAILS
Foundation depth = 5'-6" from original Ground Level
For Combined footings: Rebar- 12mm ф @ 150mm c/c both ways (bottom)
16mm ф @150mm c/c (top main bar)
12mm ф @ 150mm c/c (top secondary bar)
Eff. Depth of footing (d): 600mm and 650mm
(Details shown in str. dwg.)
BEAM REINFORCEMENT BARS
For Floor beams:
At supports (top) rebar; 2-16mm ф (regular) + 2-20mmф (extra)
At mid (bottom) rebar; 2-16mmф (regular)
(Details shown in str. dwg.)
For Plinth Tie-beams:
At support (top) rebar; 3-16mmф (regular)
At mid (bottom) rebar; 3-16mmф (regular)
Note: - Stirrups at Beam;
8mm ф @ 4"c/c at support; 6"c/c at Mid
COVER TO REINFORCEMENTS:
Minimum values for nominal cover to be provided to all reinforcement, including links of
normal weight aggregate concrete depending on the condition of exposure and minimum
specified period of fire resistance.
Environment exposure conditions considered are ‘moderate’ for sub structure, and ‘mild’ for
superstructure. Minimum fire rating considered is four hours for columns, two hours for
beams and one hour for slabs.
Clear Cover to the main reinforcement in the various structural elements depends on above
criteria shall be:
a) Footing (Bottom) 50 mm
Footing (Top and Sides) 50 mm
b) Columns 40 mm
c) Pedestals 40 mm
d) Beams 30 mm or bar diameter whichever is greater
e) Slabs 20 mm
f) Staircase waist slab 20 mm
g) Water tank walls and slabs 30 mm
h) Retaining walls (Earth Face) 25 mm
i) Retaining walls (Other Face) 20 mm
DUCTILE DETAILING
Detailing provisions of IS:13920 have been followed as applicable for a Special Moment
Resisting Frame with shear walls, in order to provide appropriate ductile properties to the
structure and improve Seismic Response of the structure.
