ABBREVIATIONS A
bf D
-
-
Area Effective width of flange 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
E C C
-
Modulus of elasticity of concrete
EL
-
Earthquake load
Es
-
Modulus of elasticity of steel
f ck ck
-
characteristic cube compressive strength of concrete
f y
-
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 column
lef
-
Effective span of beam or slab or effective length of
lex
-
Effective length about x-x axis
ley
-
Effective length ab 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
column
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
l’2
-
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 Radius
r
-
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
γf
-
Partial safety factor for load
γm
-
Partial safety factor for material
δm
-
Percentage reduction in moment
-
Creep strain of concrete
σcbc
-
Permissible stress in concrete in bending compression
σcc
-
Permissible stress in concrete in direct compression
σsc
-
Permissible stress in steel in compression
σst
-
Permissible stress in steel in tension
σsv
-
Permissible tensile stress in shear reinforcement
τc
-
Shear stress in concrete
τc,max
-
Maximum shear stress in concrete with shear
reinforcement τv
-
Nominal shear stress
φ
-
Diameter of bar
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
l’2
-
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 Radius
r
-
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
γf
-
Partial safety factor for load
γm
-
Partial safety factor for material
δm
-
Percentage reduction in moment
-
Creep strain of concrete
σcbc
-
Permissible stress in concrete in bending compression
σcc
-
Permissible stress in concrete in direct compression
σsc
-
Permissible stress in steel in compression
σst
-
Permissible stress in steel in tension
σsv
-
Permissible tensile stress in shear reinforcement
τc
-
Shear stress in concrete
τc,max
-
Maximum shear stress in concrete with shear
reinforcement τv
-
Nominal shear stress
φ
-
Diameter of bar
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 public hospital is considered considered to be a preferable option option for the not- sorich lot of people who despite acute illness can’t 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 buildi building ng is designed designed for Basement Basement+ + Lower Ground Ground + Ground Ground +4 floors. floors. OPDS, OPDS, Regis Registra tratio tion n Facili Facilitie tiess are plann planned ed in Groun Ground d floor. floor. Baseme Basements nts are are used used for for occupying various services like Medical Gases, Laundry, Electrical room, Generator etc. Operation theatres, Wards, Labour Rooms, pediatrics wards and Nursing Station are planned planned in Other Other Floors. Floors. So it is planne planned d to construc constructt Basement Basement+ + Lower Lower Ground+ Ground+ Ground Ground floors (3 floors) floors) for accommoda accommodating ting the important important facilitie facilitiess which which is inevitable inevitable for the functionin functioning g of M&C Hospital. Hospital. A Ramp is is provided provided for connec connecting ting all all the floors. floors. The other 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 submitted soil soil report report of nearest nearest building. building. The Sbc recomm recommende ended d by soil expert expert was 2
150kN/m 1.5m from GL. The Building is proposed with two basements, so the founding level will be 4m below from existing existing GL, the N value at this this level is good and hence hence the calculation of Sbc at this level yields as 200kN/m 2. The design of foundation was done 2
adopting a sbc of 200kN/m and the DPR was submitted to Executive Engineer. On scrutiny of the same, he doubted bout the adoption of Sbc and the the joint site visit with 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 ordi nate from Mar Athanasius College of Engineering.
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 dead loads are in in accordance accordance with with IS 875 – Part 1 (1987). (1987). For the calculation of dead load acting over beams at various levels the unit weight of the the building materials are taken 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 structure is taken by the software itself. The unit weight of hollow brick masonry is taken as =20 kN/m
3
The unit weight of concrete is taken as
=25 kN/m
3
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/m
Load considered for water tank
= 15 kN/m
2
2
Live loads The live live loads are are in accordanc accordance e with IS 875 – Part 2 (1987). (1987).
Live load (kN/m2)
type Wards, Nursing stations
2
Operating Operating rooms, rooms, X rays, Scan, Scan, store
3
Stair cases, Balconies, Corridors, OPDs, Offices, Laboratories, laundries, Kitchen
4 2.5 3
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 building – all 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 it’s 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: V B = Ah W
where, V B = The design base shear Ah = Design horizontal acceleration spectrum value using the fundamental natural
W = Seismic weight of the building.
The design horizontal seismic coefficient Ah
Z I Sa 2Rg
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. S a g
Average response acceleration coefficient.
Distribution of Design Force
The design base shear V B was distributed along the height of the buildings as per the following expressions.
Qi VB
W i hi
2
in
W h i
2
i
i 1
Where, Qi = Design lateral force at floor i W i = Seismic weight of floor i
n = Number of storey’s 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
Percentage of imposed load
loads kN/m²
%
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) h = height of building exclude basement floor
= 0.09h/ d = 20.30 m
d- base dimension at plinth level in respective direction=36.6 = 0.50sec For 0.1
Sa /g = 2.5
(Clause 6.4.5) Zone factor (clause 6.4.2 table 2) Importance factor (clause6.4.2 table 6)
Z = 0.16 (zone 3) I = 1.5
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.
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
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, Poisson’s 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.
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 outof-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
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
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
Completed Model
Completed Extruded Model
Completed Extruded Model of Ramp
DESIGN OF ELEMENTS Analysis Results
Axial Force on Columns
Bending Moment Diagram of Beams
Shear Force Diagram of Beams
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 2
hence the calculation of Sbc at this level yields as 200kN/m . The design of foundation was done adopting a sbc of 200kN/m 2 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. 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%
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
Geotechnical Capacity of Piles
450mmDia
500mm dia
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
Total No of Pile
=134 No.s
= 3.6m
Base Shaer( Result from Etabs)= 4354kN Horizontal Force M
td
t h i
=32.73kN t l fo
117 8kN
Factored Moment
Mu
=176kN-m
For 450mm dia pile;
P
=970kN
Pu
=1445kN
Pu f ck D 2 = (1445x1000)/ (25x4502)
=0.284
M u f ck D
3
176 10
6
25 450
3
=0.077 Providing 40 mm clear cover and assuming 20 mm dia bar d'
=50
d 1 D = 0.106 P f ck
.062 , p = 1.55
pmin= 0.8 Area of longitudinal steel
2 As 2403 mm
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 2
=635 mm
Hence provide 6 nos of Y16mm dia bars as longitudinal reinforcement Provide circular links of 8 mm dia at 150 mm c/c spacing. Provide circular spacers of 12mm dia at 3000mm c/c
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
Pu f ck D 2 = (1650x1000)/ (25x5002)
=0.264
M u f ck D
3
196 10
6
25 500
3
=0.062 Providing 40 mm clear cover and assuming 20 mm dia bar d'
=50
d 1 D = 0.10 P f ck
.041 , p = 1.01
pmin= 0.8 Area of longitudinal steel
As 1982 mm 2
This is to be provided up to fixity depth 8d = 4m Hence provide 10 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 =785 mm2 Hence provide 5 nos of Y16mm dia bars as longitudinal reinforcement Provide circular links of 8 mm dia at 150 mm c/c spacing. Provide circular spacers of 12mm dia at 3000mm c/c Design of Pile Cap Two pile group Material Constants Concrete, f ck = 25 N/mm² Steel,
f y = 500 N/mm²
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
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 2
Mu / (bd )
% of tension steel, pt
= 1030 kN-m = 1.69 = 0.428
Area of tension reinforcement, Ast =
3425mm²
Provide reinforcement of Y25mm dia bars 7 Nos Area of steel provided
= 3430 mm²
Hence Maximum shear force on pile cap = 1100kN Ultimate shear, V u
= 1650 kN
Nominal shear stress,
τv
100 As/ (bd ) Deign shear strength, τ c ie, τ v > τ c
= 2.4 N/mm² = 0.48 = 0.49 N/mm²
so shear reinforcement are needed
Assume 12mm dia 6 legged stirrups V us
= V u - τ c bd
Diameter of bar Area of shear reinforcement effective in shear, Asv
= 1372 kN = 12 mm = 678.58 mm²
Provide Y12 mm dia 6 legged stirrups Spacing of shear reinforcement, Sv
= 0.87 x d x f y x Asv V us
<300mm c/c Provide Y20 mm dia 6 legged stirrups at 200mm c/c As per IS 456:200 Depth of pile cap is greater than 750 mm. Hence side face reinforcement is needed. Side face reinforcement
= 0.1 % of web area = 0.1 x 800 x900/100 = 720 mm²
Side face reinforcement on one face
= 360 mm²
Hence provide 5 Nos of Y10mm diameter bar on one face
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
3 Design of column subjected to biaxial bending (with reinforcement equally on all the four sides.) Ref IS 456-2000 & SP 16 charts for compression with bending
f ck N/mm 30
f y 2
size of column
N/mm 500
2
design loads & moments
m 3.4
bar dia.
d
mm 16
mm 48.00
b
D
Pu
Mux
Muy
mm 500
mm 500
kN 3560
kN.m 10
kN.m 16
mm 40
Lex/D
Ley/b
Check for short or slender column unsupported unsupported Leff/L Elx Ely Lx, Cl 25.1.3 Ly, Cl 25.1.3 m 3.4
Cc
1.200
effective length Lex Ley m 4.08
1.200
Result Cl 25.1.2
m 4.08
8.16
8.16
Lex/D
Ley/b
< 12,s hort
<12, short
Longitudinal steel percentage assumed for column Reinf. details at support p Asc Nos. dia assumed p prov. 2 mm mm % % 8 20 4 16 1.33 3317.52 1.33 Additional moments in slender column / Pbx, SP 16 Table 60 d /D Pbx obtained considered k1 k2 value
value
0.096
0.10
Puz
0.207
reduction factor, k
Cl 39.6
kN 4576.988
0.425
ky 0.353
Pby, SP 16 Table 60
o bt ai ne d
c on si de red
value
value
0.096
0.10
additional moments
additional moments
Cl 39.7.1
Cl 39.7.1.1
Cl 39.7.1.1
kx 0.353
kN 1693.81
/
d /b k1
k2
Pby
0.207
0.425
kN 1693.81
Mux1
Muy1
kN.m 131.250
kN.m 131.250
Max ,kN.m May ,kN.m Max ,kN.m May ,kN.m
0.000
0.000
0.000
0.000
Moments due to minimum eccentricity minimum eccentricity Cl 25.4
ex
ey
0.023
0.023
moments due to minimum eccentricity
Mex,kN.m Mey,kN.m 83.54 83.54
Total moments to be considered for column design are: Mux Muy Pu/f ck bD p/fck Chart No 45 SP16 kN.m 83.54 Pu/Puz
kN.m 83.54 n
Cl 39.6
Cl 39.6
0.778
1.963
/
0.475
0.04 n
d /D 0.10
(Mux/Mux1) + (Muy/Muy1)
n
<1
Mux1/f ck b D
0.035 Result
IS 456-2000 Cl 39.6
Cl 39.6
0.82
<1 Ok
Chart No 46 SP16 2
/
d /b 0.10
Muy1/f ck b D
0.035
2
ETABS 2013 13.1.3
License #*192TZNDF9YDF4PW
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)
GF
C83
C300X500
DCON7
0
LLRF
3900
0.594
Section Properties b (mm) h (mm) dc (mm) 300
500
Cover (Torsion) (mm)
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 ɣC
ɣS
1.5
1.15
Axial Force and Biaxial Moment Design For P u , M u2 , M u3 Design P u kN
Design M u2 kN-m
Design M u3 kN-m
Minimum M 2 kN-m
Minimum M 3 kN-m
2092.8237
-45.7945
142.2591
41.8565
48.693
Rebar Area Rebar % mm² % 3152
2.1
Axial Force and Biaxial Moment Factors K Factor Length Initial Moment Unitless mm 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
Final Model with Pile.EDB
Page 1 of 2
7/16/2014
ETABS 2013 13.1.3
License #*192TZNDF9YDF4PW
Shear Design for V u2 , V u3 Shear V u kN
Shear V c kN
Shear V s kN
Shear V p kN
Rebar A sv /s mm²/m
Major, V u2
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 Shear Force V Top kN kN
Shear V u,Tot kN
Shear Vc kN
Joint Area cm²
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) Ag cm²
A sc cm²
1500
31.5
P uz kN
Pb kN
Pu kN
k Unitless
3207.0354 989.5549 2092.8237
0.502467
Additional Moment (IS 39.7.1) Consider Length Section KL/Depth KL/Depth KL/Depth Ma Ma Factor Depth (mm) Ratio Limit Exceeded Moment (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
Final Model with Pile.EDB
Page 2 of 2
7/16/2014
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
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
f y
f ck
b
D
Cc
Cg of bar
d
Mu lim
pt lim
N/mm2 500
N/mm2 25
mm 200
mm 500
mm 25
mm 8
mm 467
kN.m 145.03
% 0.94
Mu support
Ast req. spt
pt req.spt
Mu span
Ast span
pt req.span
% 0.86
kNm 55
mm
%
d req mm
d prov mm
Result
288.73
0.31
450.56
467
okay
2
kNm 135
mm 802.93
check for depth
Reinforcement details provided at support and span of beam Reinf. details at support Nos.
Reinf. details at span
dia
Ast support
pt support
mm
mm
%
804.25
0.86
2
16
2
16
Result
Nos.
okay
dia
Ast span
mm
mm
pt span %
804.25
0.86
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
f ck
Vu
N/mm2 25
pt
Cl 40.1 prov. N/mm2 % 0.86 1.18
kN 110
c
v
c max
Table 19
Table 20
N/mm2 0.61
N/mm2 3.1
Result tau_v > tau_c,design for shear tau_v
Design for shear reinforcement (vertical stirrups) Ref IS 456-2000 Cl 40.4a
Vu kN 110
c b
d
Vus req kN 53.03
kN 56.97
Vus/d req kN/cm 1.14
f y
2
N/mm 415
assuming
no.
stirrup dia of stirrup mm legs 8 2
stirrup sp assumed
Vus/d prov.
kN/cm
mm 100
Cl 40.4 a
MFt
MFc
1.924
1
3.630
Check for minimum and maximum spacing of stirrup Min stirrup
Max stirrup
spacing mm
spacing mm
C l 2 6. 5. 1. 6
Cl 26 .5 .1 .5
546.64
300
stirrup sp prov. mm 100
Result
Hence ok
Side face reinforcement Ref IS 456-2000 Cl 26.5.1.3
D of web mm 500
b
mm 200
side face reinf. req. / face
2
side face reinf. mm /face prov.
spc b/w bars not to
no.
dia of
Ast prov.
exceed
Cl 26.5.1.3
per face
bar
Cl 26.5.1.3
not req
2
12
mm 226.19
span
d
pt req.
pt prov.
pc
mm 5250 Result
mm 467
% 0.31
% 0.86
% 0
200 mm
Check for span to depth ratio Ref IS 456-2000 Cl 23.2.1
f y
Type of beam l/d
N/mm 500 l/d
prov
Cl 23.2.1
Cl 23.2.1
11.24
50.02
Okay
Cont.Beam
2
Design of slab Design of slab Material Constants: Concrete, f ck = 25 N/mm² Steel,
f y = 500 N/mm²
Loads: Using
120 mm thick slab
Dead Load on Slab = 0.12 x 25 = 3 kN/m² Live Load on Slab =
3kN/m²
Finishes
1.5 kN/m²
=
Partition load
=
2.5 kN/m²
Total
=
10.0 kN/m²
Boundary Conditions –one long edge discontinuous Assume a clear cover of 20 mm & 8 mm dia bars Eff: depth along shorter direction d x
= 96 mm
Eff: depth along longer direction dy
= 88 mm
Effective span as per IS 456: 2000 clause 22.2.b l yef f = 3.2+0.088 = 3.288 m l xeff = 3.9+0.096 = 3.996 m l yeff /l xeff =1.22, Hence design as Two Way Slab.
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
Result <2, Hence two way slab
Grade of concrete, steel, & overall depth of slab f y f ck b D N/mm 500
2
2
N/mm 25
mm
mm
1000
120
Lx-shorter span Cc bot
Cg of bot bar
d bot
Cc top
Cg of top bar
d top
mm
mm
mm
mm
mm
mm
20
4
96
20
4
96
Cg of top bar
d top
Ly-longer span d bot Cc top
Cc bot
Cg of bot bar
mm
mm
mm
mm
mm
mm
20
12
88
20
12
88
Load calculation of the slab Dead Load of the slab
Floor finish of the slab
Total Live load Misc. load unfactored of the slab of the slab load of the slab
Partial safety factor
Design load of the slab
f
DL kN/m
FF kN/m
LL kN/m
ML kN/m
TL kN/m
IS 456-2000
w kN/m
3
1.5
3
0
7.5
1.5
11.25
Table 18
Moment & Shear calculation Moment calculation for '1m' strip of the slab spanning Lx w
2
Lx 2
kN/m 11.25
m
w Lx kNm
3.2
115.20
- Mux cont. edge 'kNm' -
x
-
0.049
x w
2 Lx
+ Mux mid-span 'kNm' +
x
5.64
0.037
Ast min
pt req.span
+
x w
Vu 'kN' Table 13 IS 456
2 Lx
4.26
Coef-shear
C w Lx
0.600
21.60
Calculation of Ast req for slab spanning Lx Ref IS 456-2000 Cl G-1.1b & G-1.1c - Mux cont. Ast min pt req.cont. + Mux span kNm 5.6448
2
mm 144.00
%
kNm
mm
%
0.15
4.26
144.00
0.15
Reinforcement details provided at support and span of slab spanning Lx Reinf. details at support dia prov.
Reinf. details at span
spacing
Ast cont.
mm
mm
mm
%
8
150
0
250
335.10
0.35
Result
pt cont.
dia prov.
spacing
Ast span
pt span
mm
mm
mm
%
8
150
0
150
335.10
0.35
okay
Moment calculation for '1m' strip of the slab spanning Ly w
Lx 2
kN/m 11.25
2
m
w Lx kNm
3.2
115.20
- Muycont. edge 'kNm' -
y
0.037
-
y w
2 Lx
4.26
+ Muy mid-span 'kNm' +
y
0.028
+
y w
2
Lx
3.23
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 kNm 4.26
2
mm 144.00
Ast min
pt req.span
%
kNm
mm
%
0.16
3.23
144.00
0.16
Reinforcement details provided at support and span of slab spanning Ly Reinf. details at support
Reinf. details at span
dia prov.
spacing
Ast cont.
pt cont.
mm
mm
mm
%
8
150
0
250
335.10
0.38
Result
okay
dia prov.
spacing
Ast span
pt span
mm
mm
mm
%
8
150
0
250
335.10
0.38
MFt
MFc
2.936
1
Check for shear in solid slabs for limit state design method Ref IS 456-2000 Cl 4 0.1, Cl 40.2.3, Table 19, Table 20 & Cl 40.2.1.1 f ck
Vu
b
N/mm
kN
mm
25
21.6
1000
pt
k
v
%
Cl 40.1 N/mm
0.35
0.23
D
c
clear
cg
of slab mm cover mm of bar mm 120
20
3.1
d mm
4
c max
96
Result
Cl 40.2.1.1 Table 20 N/mm N/mm 0.55
tau_v < k tau_c, Ok tau_v <1/2 tau_c max,Ok
Check for span to depth ratio Ref IS 456-2000 Cl 23.2.1 f y Type of span beam
2
d
pt req.
pt prov.
pc
mm
mm
%
%
%
Cont.slab
N/mm 500
3200
96
0.15
0.35
0
l/d
l/d
Result
prov
Cl 23.2.1
Cl 23.2.1
33.33
76.34
Okay
DESIGN OF DOG LEGGED STAIRCASE
Data Internal Dimensions Length Width Floor Height Fck Fy Riser Tread Landing width Effective Span Height of each flight No. of risers in each flight No. of Tread in each flight
= = = = = = = = = =
4.76 2.6 3.9 25 500 160 280 1200 4.8 1.95 12.1875 11.1875
m m m N/mm N/mm mm mm mm m m Nos Nos
d
=
152
mm Required
D d
= =
175 154
mm mm
=
.
Design
Loads DL on horizontal area DL of steps LL FF Total load Factored load
kN/m kN/m kN/m kN/m kN/m (of one flight)
= = = = = =
5.04 2 5 1.5 13.54 20.3
= =
58 49
kN-m kN
146
mm
= = =
2.466 0.652 1005
% mm
= =
12 112
mm mm
Ast
=
185
mm
Dia of bar Spacing
= =
8 270
mm mm
BM and SF Mu Vu d from BM consideration k pt Ast
Main Reinforcement Dia Spacing
D i s t r i b u t i o n S t e el
D e v e lo p m e n t L e n g t h
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
ETABS 2013 13.1.3
License #*192TZNDF9YDF4PW
ETABS 2013 Shear Wall Design IS 456:2000 Pier Design Pier Details S tory 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 ΓS
ΓC
IP MAX
IP MIN
P MAX
1.15
1.5
0.02
0.0025
0.8
Pier Leg Location, Length and Thickness Station Location
ID
Left X 1 mm
Left Y 1 mm
Right X 2 mm
Right Y 2 mm
Length Thickness mm mm
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 (mm²)
Required Current Flexural Reinf Ratio Reinf Ratio Combo
Pu kN
M u2 kN-m
M u3 kN-m
Pier A g mm²
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 Shear Combo mm²/m
Pu kN
Mu kN-m
Top
Leg 1
OS
DW AL12
430.2772 1013.9719 -1311.7222 130.8789
500.7702
Top
Leg 2
1018.78
DW AL7
297.3436 -172.3923
272.992
50.4431
272.992
Top
Leg 3
OS
DW AL11
493.7266 -892.7358
1127.576
115.2453
4 31.0062
Bottom
Leg 1
OS
D WAL12
72.6428 -1121.5661
-1314.807
147.0513
516.9426
Bottom
Leg 2
861.61
DW AL9
167.9797
238.6595
50.4431
238.6595
Bottom
Leg 3
OS
D WAL12
878.7701 -880.6772
189.7462
Vu kN
Vc kN
-1092.6488 153.1835
Vc+ Vs kN
468.9444
Number of legs where shear force exceeds max allowed (top, bottom) = 2, 2
Final Model with Pile.EDB
Page 1 of 2
7/16/2014
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
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.
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
Design of Retaining Wall
Height of Earth Filling
=3.6m
Thickness of Wall Assumed
=200mm
Unit weight of Soil
= 17kN/m
Surcharge Pressure
= 5kN/m
Co efficient of Active Earth Pressure
=0.33
Earth pressure
3
(Kah)
2
2
2
=25kN/m taperded to top to a Value 0 kN/m
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.
Moments in Plate Maximum Vertical Moment Mx = 50kNm
Moments in Plate Maximum Horizontal Moment Mx = 30kNm
