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OUTLINEOUTLINE
1.1. INTRODUCTIONINTRODUCTION
2.2. BEAM DESIGNBEAM DESIGN2.1. FLEXURE2.1. FLEXURE
2.2. SHEAR & TORSION2.2. SHEAR & TORSION
2.3. DESIGN FOR ANCHORAGE2.3. DESIGN FOR ANCHORAGE
2.4. STAAD PRO INPUT PARAMETERS2.4. STAAD PRO INPUT PARAMETERS
2.5. STAD DESIGN OUTPUT FOR BEAMS2.5. STAD DESIGN OUTPUT FOR BEAMS
2.6. SEISMIC REQUIREMENTS FOR BEAMS2.6. SEISMIC REQUIREMENTS FOR BEAMS
OUTLINEOUTLINE
3. COLUMN DESIGN3. COLUMN DESIGN3.1. COLUMN INTERACTION DIAGRAM3.1. COLUMN INTERACTION DIAGRAM
3.2. STAAD DESIGN BRIEF FOR COLUMNS 3.2. STAAD DESIGN BRIEF FOR COLUMNS
3.3. STAAD DESIGN OUTPUT FOR 3.3. STAAD DESIGN OUTPUT FOR
COLUMNSCOLUMNS
3.4 SEISMIC REQUIREMENTS FOR 3.4 SEISMIC REQUIREMENTS FOR
COLUMNSCOLUMNS
4. CONCLUSION4. CONCLUSION
1. INTRODUCTION1. INTRODUCTION
Analysis part is always followed by the Analysis part is always followed by the
design part.design part.
However, it must be noted that the initial However, it must be noted that the initial
proportioning of beam and column sizes proportioning of beam and column sizes
is part of the design and may not be the is part of the design and may not be the
final dimension. final dimension.
Thus the Thus the design is a series of iteration design is a series of iteration
and resizingand resizing, then reanalysis, then , then reanalysis, then
redesign.redesign.
Design is an iteration process:Design is an iteration process:
1.1. Initial sizing of beams and columns.Initial sizing of beams and columns.
2.2. Analysis for stresses.Analysis for stresses.
3.3. Design of steel reinforcements.Design of steel reinforcements.
if design is inadequate, repeat step if design is inadequate, repeat step
1, 2, and 3.1, 2, and 3.
4. 4. If design is adequate, adopt sizes If design is adequate, adopt sizes
and reinforcements.and reinforcements.
1. INTRODUCTION1. INTRODUCTION
All concrete design calculation is All concrete design calculation is
governed by the current ACI 318 code.governed by the current ACI 318 code.
Unified (strength) design method is Unified (strength) design method is
adopted by the current code.adopted by the current code.
The working stress design (WSD) is The working stress design (WSD) is
deleteddeleted from the ACI 318 codefrom the ACI 318 code
STAAD Pro STAAD Pro do not do not employ the WSD for employ the WSD for
reinforced concrete design.reinforced concrete design.
1. INTRODUCTION1. INTRODUCTION
SPECIAL MOMENT RESISTING FRAMES SPECIAL MOMENT RESISTING FRAMES
(SMRF) (SMRF) are the type of frames, instead of are the type of frames, instead of
ORDINARY MOMENT RESISTING ORDINARY MOMENT RESISTING
FRAMES (OMRF) FRAMES (OMRF) are required for high are required for high
seismic risk areas, such as the seismic risk areas, such as the
Philippines.Philippines.
Therefore, the NSCP requires that all Therefore, the NSCP requires that all
buildings in the Philippines must be buildings in the Philippines must be
designed to effectively designed to effectively resist high resist high
seismic forces.seismic forces.
1. INTRODUCTION1. INTRODUCTION
At the moment, STAAD Pro has At the moment, STAAD Pro has
NO provisionNO provision for automatic for automatic
seismic detailing in reinforced seismic detailing in reinforced
concrete design.concrete design.
What shall we do????What shall we do????
1. INTRODUCTION1. INTRODUCTION
FLEXUREFLEXURE
SHEARSHEAR
TORSIONTORSION
22. . BEAM DESIGNBEAM DESIGN
2.1. FLEXURE2.1. FLEXURE
The main (longitudinal) reinforcement is The main (longitudinal) reinforcement is
calculated for calculated for midspanmidspan (sagging) and (sagging) and
support (hogging) bending moments on support (hogging) bending moments on
the basis of the section profile in the the basis of the section profile in the
design brief (design brief (ieie. PRISMATIC ZD, YD). . PRISMATIC ZD, YD).
22. . BEAM DESIGNBEAM DESIGN
22. . BEAM DESIGNBEAM DESIGN
CRITICAL SAGGING MOMENT
CRITICAL HOGGING MOMENT
CRITICAL HOGGING MOMENT
ZONE 1 ZONE 2 ZONE 3
22. . BEAM DESIGNBEAM DESIGN
2.1. FLEXURE2.1. FLEXURE
TheThe STAAD Pro does not have any limit STAAD Pro does not have any limit
of any bars in any one layer as long as of any bars in any one layer as long as
the spacing requirements specified in the spacing requirements specified in
the code are satisfied.the code are satisfied.
TheThe program can handle a maximum of program can handle a maximum of
four layers of reinforcement, two layers four layers of reinforcement, two layers
each at the top and bottom.each at the top and bottom.
22. . BEAM DESIGNBEAM DESIGN
2.1. FLEXURE2.1. FLEXURE
TheThe actual amount of steel required as actual amount of steel required as
well as the maximum and minimum well as the maximum and minimum
required for required for flexure is shown as ROW, flexure is shown as ROW,
ROWMX AND ROWMIN, respectively.ROWMX AND ROWMIN, respectively.
It is important to note that the beams are It is important to note that the beams are
designed for flexural MZ only. The designed for flexural MZ only. The
moment My is not considered in the moment My is not considered in the
design.design.
bh x
MY
y
MZ
Top bars
(max of 2 layers)
22. . BEAM DESIGNBEAM DESIGN
2.1. FLEXURE2.1. FLEXURE
bottom bars
(max of 2 layers)
22. . BEAM DESIGNBEAM DESIGN
2.2. SHEAR & TORSION2.2. SHEAR & TORSION
d
d
SFACE
OR
EFACE
BEAM ELEMENT LINE
COLUMN ELEMENT LINE
SHEAR FORCE AND TORSIONAL
MOMENT LOCATION CALCULATED
STEEL REINFORCEMENTS
22. . BEAM DESIGNBEAM DESIGN
2.2. SHEAR & TORSION2.2. SHEAR & TORSION
When required, torsional reinforcement in
the form of closed stirrups or hoop
reinforcement must be provided.
22. . BEAM DESIGNBEAM DESIGN
2.2. SHEAR & TORSION 2.2. SHEAR & TORSION
22. . BEAM DESIGNBEAM DESIGN
2.2. SHEAR & TORSION2.2. SHEAR & TORSION
In addition to the stirrups, longitudinal
steel bars are provided in corners of the
stirrups and are well distributed around
the section
22. . BEAM DESIGNBEAM DESIGN
2.2. SHEAR & TORSION2.2. SHEAR & TORSION
22. . BEAM DESIGNBEAM DESIGN
2.2. SHEAR & TORSION 2.2. SHEAR & TORSION
In the ACI Code, the design for torsion is In the ACI Code, the design for torsion is
based on space truss analogy.based on space truss analogy.
After After torsionaltorsional cracking occurs, the cracking occurs, the
torque is resisted by closed stirrups, torque is resisted by closed stirrups,
longitudinal bars, and concrete longitudinal bars, and concrete
compression diagonals.compression diagonals.
22. . BEAM DESIGNBEAM DESIGN
2.3. DESIGN FOR ANCHORAGE2.3. DESIGN FOR ANCHORAGE
In STAAD output for flexural design, the
anchorage requirement is shown with a
YES or NO at the START and END of the
beam. The designer must provide the
details of anchorage.
4db
5db
6db
4db or 2.5 min
D
PPPPWWRRPPPP'' GGEEPPPPPPPPPPPP'' GGEEPPPPPPPP'' GGEE
++RRRRNNLLIIDDQQFFKKRRUULLVV
2.42.4. . STAAD PRO INPUT PARAMETERSSTAAD PRO INPUT PARAMETERS
Parameter Default Value Description
FYMAIN * 60,000 psi (414 MPa) Yield Stress for main reinforcing
steel
FYSEC * 60,000 psi (414 MPa) Yield Stress for Secondary Steel
FC * 4,000 psi (28 MPa) Compressive Strength of
Concrete
CLT *1.5 inch (37.5 mm) Clear cover for top
reinforcement
CLB *1.5 inch (37.5 mm) Clear cover for bottom
reinforcement
CLS *1.5 inch (37.5 mm) Clear cover for side
reinforcement
MINMAIN** #4 (12mm) Min main reinforcement bar size
MINSEC ** #4 (12mm) Min secondary reinforcement
bar size
MAXMAIN ** #18 (57 mm) Max main reinforcement bar size
NSECTION*** 12 Number of equally-spaced sections to be considered
in finding critical moments for beam design.
TRACK 0.0 BEAM DESIGN:
With TRACK set to 0.0, critical moments will not be
printed out with beam design report.
A value of 1.0 will mean a print out.
A value of 2.0 will print out required steel areas for al
intermediate sections specified by NSECTION.
COLUMN DESIGN:
TRACK 0.0 prints out detailed design results.
TRACK 1.0 prints out column interaction analysis
results in addition to TRACK 0.0 output.
TRACK 2.0 prints out schematic interaction diagram
and intermediate interaction values in addition to all
of the above.
RHOMN 0.01
(1%)
Minimum reinforcement required in a concrete
column. ACI code allows 1% to 8%.
2.42.4. . STAAD PRO INPUT PARAMETERSSTAAD PRO INPUT PARAMETERS
UNIT KN METERUNIT KN METER
START CONCRETE DESIGNSTART CONCRETE DESIGN
CODE ACI 2002CODE ACI 2002
FYMAIN 414 ALLFYMAIN 414 ALL
MAXMAIN 20 ALLMAXMAIN 20 ALL
CLB 40MMCLB 40MM
DESIGN BEAM 17 10DESIGN BEAM 17 10
END CONCRETE DESIGNEND CONCRETE DESIGN
EXAMPLE EXAMPLE
DESIGN BRIEF FOR BEAMSDESIGN BRIEF FOR BEAMS
nn In STAAD Pro V8i (SELECT Series 1), In STAAD Pro V8i (SELECT Series 1),
three versions of the ACI Code are three versions of the ACI Code are
implemented: 1999, 2002, and 2005implemented: 1999, 2002, and 2005
nn To access any of the code editions, To access any of the code editions,
specify the commandsspecify the commands
START CONCRETE DESIGNSTART CONCRETE DESIGN
CODE ACI 1999 CODE ACI 1999 (for 1999)(for 1999)
or CODE ACI 2002 or CODE ACI 2002 (for 2002) (for 2002)
or CODE ACI or CODE ACI (for 2005)(for 2005)
EXAMPLE EXAMPLE
DESIGN BRIEF FOR BEAMSDESIGN BRIEF FOR BEAMS
BEAM NO. 97 DESIGN RESULTS BEAM NO. 97 DESIGN RESULTS -- FLEXURE PER CODE ACI FLEXURE PER CODE ACI 318318--0505LEN LEN -- 5000. MM FY 5000. MM FY -- 275. FC 275. FC -- 21. MPA, SIZE 21. MPA, SIZE -- 300. X 400. MMS300. X 400. MMSLEVEL HEIGHT BAR INFO FROM TO ANCHORLEVEL HEIGHT BAR INFO FROM TO ANCHOR(MM) (MM) (MM) STA END(MM) (MM) (MM) STA END__________________________________________________________________________________________________________________1 54. 5 1 54. 5 -- 12MM 802. 3989. NO 12MM 802. 3989. NO NONO2 342. 4 2 342. 4 -- 20MM 0. 1484. YES NO20MM 0. 1484. YES NO3 342. 4 3 342. 4 -- 20MM 3308. 5000. NO YES20MM 3308. 5000. NO YES____________________________________________________________________________________________________________________
Check the output if ACI318-05 to comply with NSCP 2010
Override these values Override these values if longitudinal if longitudinal reinforcement for reinforcement for torsion is requiredtorsion is required.
2.5. SAMPLE STAAD BEAM DESIGN OUTPUT2.5. SAMPLE STAAD BEAM DESIGN OUTPUT
B E A M N O. 97 D E S I G N R E S U L T S - SHEAR
AT START SUPPORT - Vu= 68.16 KNS Vc= 81.19 KNS Vs= 9.70
KNS
Tu= 0.34 KN-MET Tc= 2.9 KN-MET Ts= 0.0 KN-MET LOAD 4
NO STIRRUPS ARE REQUIRED FOR TORSION.
REINFORCEMENT IS REQUIRED FOR SHEAR.
PROVIDE 10 MM 2-LEGGED STIRRUPS AT 178. MM C/C FOR 2158. MM
ADDITIONAL LONGITUDINAL STEEL REQD. FOR TORSIONAL
RESISTANCE = 0.00 SQ.CM.
AT END SUPPORT - Vu= 70.66 KNS Vc= 81.19 KNS Vs= 13.03 KNS
Tu= 0.34 KN-MET Tc= 2.9 KN-MET Ts= 0.0 KN-MET LOAD 4
NO STIRRUPS ARE REQUIRED FOR TORSION.
REINFORCEMENT IS REQUIRED FOR SHEAR.
PROVIDE 10 MM 2-LEGGED STIRRUPS AT 178. MM C/C FOR 2158. MM
ADDITIONAL LONGITUDINAL STEEL REQD. FOR TORSIONAL
RESISTANCE = 0.00 SQ.CM.
2.5. OUTPUT 2.5. OUTPUT OF BEAM DESIGN OF BEAM DESIGN
((SHEAR and TORSION)SHEAR and TORSION)
This is not final. This is not final.
To be checked To be checked
against seismic against seismic
provisionsprovisions
Since the Philippines is located in a high Since the Philippines is located in a high
seismic risk region, adopting the seismic risk region, adopting the SMRFSMRF
((SSpecial pecial MMoment oment RResisting esisting FFrame) rame) is a is a
must. must.
Therefore, a special detailing for Therefore, a special detailing for
seismic requirement shall is required. seismic requirement shall is required.
Unfortunately, STAAD Pro at the Unfortunately, STAAD Pro at the
moment does not have the facility for moment does not have the facility for
seismic detailing.seismic detailing.
2.62.6. . SEISMIC REQUIREMENTS FOR BEAMSSEISMIC REQUIREMENTS FOR BEAMS
At this point the design output of STAAD At this point the design output of STAAD
Pro is compliant to ACI Code 318Pro is compliant to ACI Code 318--08 or 08 or
the NSCP 2010, the NSCP 2010, EXCEPT FOR THE EXCEPT FOR THE
SEISMIC DETAILING requirements.SEISMIC DETAILING requirements.
2.62.6. . SEISMIC REQUIREMENTS FOR BEAMSSEISMIC REQUIREMENTS FOR BEAMS
Flexural Flexural Members shall satisfy the following:Members shall satisfy the following:
(ACI (ACI 318318--08 Section 21.3.1 08 Section 21.3.1 or NSCP or NSCP 421.5.1421.5.1))
1. Clear span shall not be less than four (4)
times the effective depth.
2. The width-to-depth ratio , b/d, shall not be
less 0.3.
3. The width shall not be less than 250mm
4. The width, bs, of the supporting member
plus distances on each side of the
supporting member not exceeding of
the depth of the flexural member.
2.62.6. . SEISMIC REQUIREMENTS FOR BEAMSSEISMIC REQUIREMENTS FOR BEAMS
1.1. Longitudinal reinforcement for both Longitudinal reinforcement for both
top and bottom steel (A) should be in top and bottom steel (A) should be in
the range defined as follows:the range defined as follows:
Longitudinal reinforcement requirements
(ACI code Section 21.3.2 / NSCP 421.5.1)
3 fc' bd
fy
200 bd
fy
A 0 025 bd,
2. 2. The positive moment strength at joint The positive moment strength at joint
face should be greater or equal the face should be greater or equal the
negative moment strength at the face negative moment strength at the face
of the jointof the joint
Longitudinal reinforcement requirements
(ACI code Section 21.3.2 / NSCP 421.5.1)
MnL-
MnL+ 1/2 (MnL
- )
MnR-
MnR+ 1/2 (MnR
- )
3. 3. Neither the negative nor the positive Neither the negative nor the positive
moment strength in any section along the moment strength in any section along the
member should be less than the member should be less than the
maximum strength provided at the face maximum strength provided at the face
of either joint.of either joint.
Longitudinal reinforcement requirements
(ACI code Section 21.3.2 / NSCP 421.5.1)
MnL-
max
Many section 1/4 (MnL-
max )
4.4. Lap splices of flexural reinforcement are Lap splices of flexural reinforcement are
permitted only if hoop reinforcement is permitted only if hoop reinforcement is
provided over the lap length.provided over the lap length.
Maximum spacing of transverse Maximum spacing of transverse reinfreinf
enclosing the lapped bars shall not enclosing the lapped bars shall not
exceed 100mm. exceed 100mm.
Longitudinal reinforcement requirements
(ACI code Section 21.3.2 / NSCP 421.5.1)
Lap splices shall not be used:Lap splices shall not be used:
a.a. Within the joint.Within the joint.
b.b. With a distance of twice the member With a distance of twice the member
depth from the face of the joint; anddepth from the face of the joint; and
c.c. At locations where analysis indicates At locations where analysis indicates
flexural yielding (flexural yielding (ieie. Location of plastic . Location of plastic
hinges)hinges)
Longitudinal reinforcement requirements
(ACI code Section 21.3.2 / NSCP 421.5.1)
2h 2h 2h 2h
h
Yield may occur1.
Transverse reinforcement requirements
(ACI code Section 21.3.3 / NSCP 421.5.3)
For SMRF, plastic hinges will form at the For SMRF, plastic hinges will form at the
ends of flexural members. Those ends of flexural members. Those
locations should be specially detailed to locations should be specially detailed to
ensure sufficient ductility.ensure sufficient ductility.
2. Spacing of hoops should not exceed the
following:
a. d/4
b. 8 x diameter of the smallest
longitudinal bars.
c. 24 x diameter of hoop bars.
c. 300 mm
First hoop shall be located not more than
50mm from face of support.
Transverse reinforcement requirements
(ACI code Section 21.3.3 / NSCP 421.5.3)
3. Where hoops are not required, stirrups
with seismic hooks shall be spaced at a
distance not more than d/2 throughout the
length of the member.
Transverse reinforcement requirements
(ACI code Section 21.3.3 / NSCP 421.5.3)
hhoops
2h
50mm max50mm max 50mm max
Hoop spacing is smallest of:
d/4 ; 8db ; 24 hoop db ;
300mm ; STAAD Pro output
Spacing of stirrups d/2
hoops hoops
2h 2h
Special Detailing on Transverse Reinf.
Sample of design output from STAAD Pro
56J 5000 X 300 X 400 58J
4No20 H 342. | 0 TO 148414*10c/c 178
4No20 H 342. | 3308 TO 500014*10c/c178
5No12 H 54. | 802 TO 3989
5000
400
1484 1692
4-20mm 4-20mm
5-12mm 14 hoops of 10mm@ 178 o.c.14 hoops @10mm@ 178 o.c.
802 1102
Physical representation
54
342
Beam Detail With Seismic Provision
400
800mm S=90mm
2900S=178mm
From STAAD
50mm max 50mm max
4-20mm
5-12mm
b
4-20mm
2-12mm2-12mm
10mm hoops / stirrups
2-20 mm
800mmS=90mm
b5000
Hoop spacing is smallest of : d/4 ; 8db ; 24 hoop db ;
300mm and STAAD Pro
Beam Detail With Seismic Provision
5000
400
800mm S=90mm
2900S=178mm
From STAAD
50mm max 50mm max
4-20mm
2-20mm
Hoop spacing is smallest of : d/4 ; 8db ; 24 hoop db ;
300mm and STAAD Pro
b
4-20mm
2-20mm2-20mm
10mm hoops / stirrups
2-20 mm
800mmS=90mm
b
Bottom bars of 5-12mm < 2-20mm
5-12mm 2-12mm2-12mm
33. . COLUMNCOLUMN DESIGNDESIGN
Column design in STAAD per the ACI
code is performed for axial force,
uniaxial and biaxial moments.
The loading which produces the
largest amount of reinforcement is
called the critical load.
33. . COLUMNCOLUMN DESIGNDESIGN
Column design is done for square,
rectangular and circular sections.
For rectangular and circular
sections, reinforcement is always
assumed to be equally distributed on
all faces. This means that the total
number of bars will always be a
multiple of four (4).
Column design inside the STAAD program
1. The Bresler Load Contour method is
adopted by STAAD Pro for columns
under axial force, uniaxial and biaxial
moments.
2.The program will iterate a steel ratio from
1% to a maximum of 8% for a given
column dimension.
3.When the adequate steel ratio is arrived
at, the iteration terminates and adopt the
steel ratio and then a steel area is
computed.
Column design inside the STAAD program
4. Otherwise, if the section is
inadequate, the report prompts that
the size needs to be increased.
5. Seismic provision is absent in STAAD
Pro. Thus the output must be checked
and adjusted accordingly.
Nominal Pn, Mn curve
Factored Pu, Mu
(ACI Capacity)
A
x
i
a
l
c
a
p
a
c
i
t
y
(
k
N
)
Moment Capacity (kN-m)
SAFE ZONE
for(Pu, Mu) pair
3.1. COLUMN INTERACTION DIAGRAM3.1. COLUMN INTERACTION DIAGRAM
UNIT KN METER
START CONCRETE
DESIGN
CODE ACI
FYMAIN 414
MAXMAIN 25 ALL
DESIGN COLUMN 23 25
END CONCRETE DESIGN
3.2. 3.2. STAAD DESIGN BRIEF
FOR COLUMNS
The following output is generated without any TRACK
definition, thus using the default of TRACK 0.0
==========================================================
COLUMN NO. 1 DESIGN PER ACI 318-05 - AXIAL + BENDING
FY - 415.0 FC - 25.0 MPA, RECT SIZE - 275.0 X 300.0 MMS, TIED
AREA OF STEEL REQUIRED = 882.8 SQ. MM
BAR CONFIGURATION REINF PCT. LOAD LOCATION
PHI
---------------------------------------------------------------------------------------------------------
8 - 12 MM 1.097 4 END 0.650
(PROVIDE EQUAL NUMBER OF BARS ON EACH FACE)
TIE BAR NUMBER 12 SPACING 192.00 MM
3.3. 3.3. STAAD DESIGN OUTPUT
FOR COLUMNS
33. . 44. SEISMIC REQUIREMENTS . SEISMIC REQUIREMENTS FOR FOR
COLUMNCOLUMN
1. Longitudinal Reinforcements
(NSCP2010 421.6.3.1)
The reinforcement ratio g shall not be
less than 0.01 and shall not exceed 0.06.
The STAAD allows up to a maximum of
8%. Therefore, should the design be
adequate with a steel ratio more than
6%, the section size shall be increased
in order to satisfy a steel ratio of less
than or equal to 6%.
Flexural Strength (NSCP2010 421.6.1)
The flexural strength of the column should satisfy
the following:
Mnc (6/5) Mnb
Where:
Mnc - the sum of nominal flexural strengths of
columns framing into the joint, evaluated
at the faces of the joint.
Mnb - the sum of nominal flexural strengths of
the beams framing into the joint,
evaluated at the faces of the joint.
Mncbot
Mnctop
MnbrightMnbleft
(Mnctop + Mncbot) (6/5) (Mnbtop + Mnbbot)
VXPRIFROXPQPRPHQWFDSDFLW\PXVWEHKLJKHUWKDQWKHVXPRIWKHEHDPPRPHQWFDSDFLW\
Flexural Strength (NSCP2010 421.6.1)
33. 4. SEISMIC REQUIREMENTS . 4. SEISMIC REQUIREMENTS FOR FOR
COLUMNCOLUMN
2. Limiting size of columns
(NSCP2010 421.6.1)
The shortest cross-sectional
dimension, measured on a straight
line passing through the geometric
centroid, shall not be less than
300mm. (Sec 421.6.1.1)
The ratio of the shortest cross-
sectional dimension to the
perpendicular dimension shall not be
less than 0.4. (Sec 421.5.1.2)
33. 4. SEISMIC REQUIREMENTS . 4. SEISMIC REQUIREMENTS FOR FOR
COLUMNCOLUMN
3. Transverse reinforcement spacing
(NSCP2010, 421.6.4.3)
1. of the minimum member dimension.
2. Six times the diameter of the longitudinal
bar, and
3. as defined by the given equation.
So = 100 + (350-hx)
3
where 100mm < So < 150mm
hx = spacing of additional cross ties
or overlapping hoops, which
need not exceed 350mm on
centers.
33. 4. SEISMIC REQUIREMENTS . 4. SEISMIC REQUIREMENTS FOR FOR
COLUMNCOLUMN
3. Transverse reinforcement spacing
(NSCP2010, 421.6.4.3)
b
hx hx hx
hx
hx
h
b/4
s 100+ (350- hx)
3
where
100mm
33. 4. SEISMIC REQUIREMENTS . 4. SEISMIC REQUIREMENTS FOR FOR
COLUMNCOLUMN
3. Transverse reinforcement spacing
(NSCP2010, 421.6.4.1)
The transverse reinforcements shall be provided
over a length, lo, from each joint face . The
length, lo, shall not be less than the largest of:
1.1. The depth of the member at the joint face or The depth of the member at the joint face or
where the flexural yielding is likely to occur.where the flexural yielding is likely to occur.
2.2. OneOne--sixth of the clear span of the membersixth of the clear span of the member
3.3. 450 mm450 mm..
33. 4. SEISMIC REQUIREMENTS . 4. SEISMIC REQUIREMENTS FOR FOR
COLUMNCOLUMN
3. Transverse reinforcement spacing
(NSCP2010, 421.6.4.1)
Where transverse reinforcements are not required
throughout the full length of the column, the hoops
of the remainder of the column length shall be
spaced at the smaller of :
a) 6 times the diameter of the longitudinal bars.
b) 150mm
COLUMNS WITH SEISMIC DETAILING
S
S
Clear height, lu
Larger of b or h
1/6 lu
450mm
6 Ldb
150 mm.
b
hx hx hx
hx
hx
h
b/4
s 100+ (350- hx) where 100
OUTPUT FOR COLUMN DESIGN
COLUMN NO. 333 DESIGN PER ACI 318-05 - AXIAL + BENDING
FY - 413.7 FC - 27.6 MPA, SQRE SIZE - 500.0 X 500.0 MMS, TIED
AREA OF STEEL REQUIRED = 9850.0 SQ. MM
BAR CONFIGURATION REINF PCT. LOAD LOCATION PHI
----------------------------------------------------------------------------------------------
8 - 40 MM 4.021 9 STA 0.70
(PROVIDE EQUAL NUMBER OF BARS ON EACH FACE)
TIE BAR NUMBER 12 SPACING 320.00 MM
----------------------------------------------------------------------------------------------
coincides with NSCP2010
reinf. pct is with 1% to 6%, ok.
not adequate for seismic requirements:
S= (500)=125mm
S=6(40)=240mm
S=4+(14-8.5)/3=5.8=145mm
Adopt S=125mm at lo=18 from joint
Adopt S=150mm at remainder.
125
450
450
2850
650
3500
125
150 500
500
424
424
8-40mm
12mm hoops
COLUMN DETAIL WITH SEISMIC PROVISION
BEAM / GIRDER
BEAM / GIRDER
SECTION
SAMPLE EXERCISE
800mm S=90mm
50mm max
300
2-20mm
4-20mm
300
8-20mm
400
300
STAAD Hoops without
seismic detailing:
16Lb = 16 (20) = 120
48Tb = 48 (10) = 480
Dcol = 300
Beam moment capacities:
Mnneg = 116 kN-m
Mnpos = 61 kN-m
(6/5) x (Mn++Mn-)= 212.4 kN-m
Column moment capacities:
Mnctop=Mncbot = 63 kN-m
Mnctop + Mncbot = 126 kN-m
Column is inadequate for seismic requirements.
Therefore, increase capacity of column
Mnctop
Mncbot
Mnneg
Mnpos
INCREASE COLUMN FLEXURE CAPACITY
COLUMN STRENGTH REQUIREMENT
(6/5) x (Mn++Mn-)= 212.4 kN-m
300MM X 300MM WITH 8-20MM BARS :
Mnctop +Mncbot = 126 kN-m, not ok
300MM X 300MM WITH 12-20MM BARS :
Mnctop +Mncbot = 162 kN-m, not ok
375MM X 375MM WITH 12-20MM BARS :
Mnctop +Mncbot = 219 kN-m >212.4 , thus ok
MAX STIRRUPS SPACING
a) 6 (20) = 120 mm
b) 150mm
smax = 120mm
STIRRUPS SPACING from the joints
at length lo = greater of
a) 375mm
b) 450mm
c) 1/6 of lu =1/6 (2850)=475mm
so that, lo = 450mm
1) s= b/4 = 375/4 = 94mm
2) s = 100+(350-0)/3 = 217 ,
100
REQUIRED STIRRUP SIZE
Where:
S spacing of stirrups
hc column core dimension measured from
center-to-center of confinng stirrups
Ag gross area of section
Ach area of column core
fc` - compressive strength of concrete
fyt yield strength of stirrups
Ash total area of number of legs in one
direction
s = 94mm fc` = 21 Mpa fyt = 275 Mpa
hc = 375 2 (32) = 311mm
Ag = (375)(375) = 140,625 sq.mm.
Ach = (311)(311) = 96,721 sq.mm.
REQUIRED STIRRUP SIZE
Using 10mm stirrups with 4 legs in one direction:
At = 4(78.54) = 314.16 sq.mm.
Ok since greater than 304.004 sq.mm
800mm
S=90mm
50mm max
400
300
Lo = 450
Lo = 450
4-20mm
2-20mm
smax= 120mm of 10mm hoops
sr= 94mm of 10mm hoops
375
375
12-20mm
3 sets of 10mm hoops
CONCLUSION
1.STAAD Pro output does not, as of yet,
have provisions for seismic detailing
requirement. All the generated design
results are based on maximum
stresses only.
Therefore, the output should not be
used as the final detail without
modification when designing for SMRF.
2. The seismic detailing should start first
on the beam: supports and midspan
requirements must be satisfied before
going to the columns.
Modify the beam STAAD output to suit
the seismic requirements.
CONCLUSION
3.The columns connected at a joint should
be 20% (or 6/5) stronger than the beams
connected at that same joint in terms of
flexure.
Since the beam is already fixed, the
column STAAD results must be adjusted
to fit the seismic requirements at that
joint.
CONCLUSION
4. Finally, once the seismic requirements
are satisfied, then and only then the
detailed drawings are carried out.
CONCLUSION
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