Moment Resisting Frame.pdf

LATERAL RESISTING STRUCTURAL
SYSTEM:
MOMENT RESISTING FRAME
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Presented By
Eng. ZEINAB AWADA
Email
Zeinabawada198@gmail.com
MASTER OF CIVIL ENGINEERING - LEBANON
ADVANCED STRUCTURAL SYSTEMS COURSE
Mon, Nov 29-2021

OUTLINE
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❑ INTRODUCTION
❑ CONCRETE MOMENT RESISTING FRAME
❑ STEEL MOMENT RESISTING FRAME
❑ COMPOSITE MOMENT RESISTING FRAME

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• The seismic analysis and design has traditionally focused on reducing
the risk of loss of life.
• Building codes have developed provisions around life safety concerns,
i.e., to prevent collapse under the most intense earthquake expected at
a site during its life.
• The successful performance of buildings in areas of high seismicity
depends on a combination of strength, ductility manifested in the
details of construction, and the presence of a fully interconnected,
balanced, and complete lateral-force-resisting system.
• Very brittle lateral-force-resisting systems can be excellent performers
as long as they are never pushed beyond their elastic strength.
INTRODUCTION
❖ General Requirements

❖ What is a Moment Resisting Frame!
INTRODUCTION
• Used in steel and reinforced concrete buildings
• This system consists of beams, columns and rigid joints
• Capable of resisting both vertical and lateral loads by the bending
of beams and columns
• Beam-column connections have adequate rigidity to hold the
original angles between intersecting members unchanged
• Reinforced concrete is an ideal material for this system by virtue of
its naturally monolithic behavior
• For steel buildings, rigid framing is achieved by reinforcing beam-
column connections
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❖ Disadvantages of Moment Resisting Frame!
1. Greater deflection and drift compared to that of braced frames or shear walls
2. localized stress concentrations at rigid joints
3. Requires care in the erection of connections in order to resist lateral loads
properly
4. Expensive moment connections
5. A highly rigidity in the upper floors, where there is a little deformation more than
the lower floors
1. Provides flexibility for architectural design and layout
2. Sufficient stiffness to resist wind and earthquake induced lateral loads in buildings
of up to about 25 stories
❖ Advantages of Moment Resisting Frame!
CHARACTERISTICS OF MRF

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CONCRETE MOMENT FRAME
DESIGN REQUIREMENTS AND ASSUMPTIONS
PART 1

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❖ Types of Moment Resisting Frame!
• An ordinary reinforced concrete moment is permitted
to be used in buildings assigned to SDC B
• Structures assigned to SDC C are permitted to utilize
intermediate concrete moment resisting frames
• Special reinforced concrete moment frames are
required in structures assigned to SDC D,E and F
ACI 318-19 CHAPTER 18
✓ Ordinary moment frames shall satisfy 18.3
✓ Intermediate moment frames shall satisfy
18.4
✓ special moment frames shall satisfy 18.2.3
through 18.2.8 and 18.6 through 18.8
1. Ordinary moment frames
2. Intermediate moment frames
3. special moment frames

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There are two causes of lateral drift:
1. Due to cantilever bending of the building
(bending deformation), which is
approximately 20 per cent of the total lateral
drift
2. Due to bending of the beams and columns
(shear deformation), approximately 65 per
cent is due to the bending of the beams, and
15 per cent to the columns, totaling
approximately 80 per cent of the total lateral
drift
❖ Drifts in Moment Resisting Frame

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• Capacity of building materials, systems, or
structures to absorb energy by deforming into the
inelastic range
• The capability of a structure to absorb energy, with
acceptable deformations and without failure, is a
very desirable characteristic in any earthquake-
resistant design
• Concrete, a brittle material, must be properly
reinforced with steel to provide the ductility
necessary to resist seismic forces
❖ Definition of Ductility

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• dissipate energy through their ductility and may
undergo excessive lateral deformations.
• ductility is achieved by the formation of plastic hinges in
the columns and beams.
• when they are deformed beyond their elastic limits, a
large part of the energy is dissipated by the plastic
hinges.
• ductility of reinforced concrete depends on the design.
• In reinforced concrete rigid frames, it is necessary to
design the columns to be stronger than the beams so
that plastic hinges can be formed in the beams.
❖ Ductility in Rigid Frames

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• The formation of plastic hinges at the beam-column interface
results in large inelastic strain demands at the connection leading
to brittle failure.
• the prequalified connections are designed to produce the plastic
hinges within the beam span.
• the formation of plastic hinges within the beam span is capable of
dissipating large amounts of energy, without failure.
• This condition may be achieved by reducing the section of the
beam at the desired location of the plastic hinge or by reinforcing
the beam at the connection to prevent the formation of a hinge in
this region.
❖ Strong Column–weak Beam

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• frames with columns that are weaker in flexure than the
framing beams can form weak-story mechanisms, in which
plastic hinges form at the base and top of all columns in a
story.
• large inelastic displacements produced in the columns increase
the P-delta effect and may lead to column failure.
• The strong column–weak beam concept may be achieved in
accordance with the requirement:
1. By assuring that, at each beam–column joint, the flexural
resistance of columns is substantially (20%) more than
the flexural strength of beams.
❖ Strong Column– Weak Beam

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• When axial load is imposed on the deflected shape of the
frame, additional sway occurs in the frame.
• This additional deflection imposes secondary moments in
the column.
• At any point, the total moment M can be considered as a
combination of the moment M0 due to end moments plus
the addition of the moment caused by P acting at an
eccentricity y.
• Thus, M = M0 + P∆
❖ P∆- Effect

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• The factor R in the denominator of base shear equations is an empirical response reduction factor
intended to account for both the damping and ductility.
• A higher value of R has the effect of reducing the design base shear.
• for RC special moment-resisting frame, the factor has a value of 8, whereas for ordinary moment-resisting
frame, the value is 3.
❖ Structural System Coefficient R
• This reflects the fact that a special
moment-resisting frame performs better
during an earthquake.

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ORDINARY CONCRETE MOMENT FRAMES (OMF) SDC B
❖ General Requirements: Frame Beams
• The flexural reinforcement at both top and bottom
faces of the section must include at least two
continuous bars along the span.
• The area of the Continuous bottom bars in the
section, shall have an area not less than 25% of the
maximum area of bottom bars along the span.
• These bars(flexural RFT.) shall be anchored to develop
fy in tension at the face of support.
• These requirements for structures not expected to be
subjected to strong ground motion.

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• flexural reinforcement :
1. similar to ordinary moment beams.
2. The limits of gross reinforcement ratio:
• Shear reinforcement:
a. minimum ties are required in the rectangular sections:
1. Minimum diameter of ties is 10 mm (# 3).
2. Maximum spacing of ties is given as:
✓ b = Dimension of the shorter side of the member.
✓ db = Diameter of the main reinforcement bars.
✓ dt = Diameter of the tie bars.
ORDINARY CONCRETE MOMENT FRAMES (OMF) SDC B
❖ General Requirements: Frame Columns
• The spacing of spirals:
1. smax = 80 mm (3 in)
2. smin = 25 mm (1 in)
Ratio of the volume of spirals to the
volume of concrete

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❖ Flexural Reinforcement: Frame Beams
• Positive moment strength at joint face ≥ one-
third negative moment strength provided at
that face of the joint.
• Neither the negative nor the positive
moment strength at any section along the
member length shall be less than one-fifth
the maximum moment strength provided at
the face of either joint.
• The top reinforcement is usually spliced near
mid span and the bottom reinforcement is
spliced near the support.
INTERMEDIATE CONCRETE MOMENT FRAMES (IMRF) SDC C

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❖ Transverse Reinforcement: Frame Beams
• The first stirrup shall be located no more than 2 in or
50mm, from the face of the supporting member.
• Maximum stirrup spacing shall not exceed
• d/4.
• 8 × diameter of smallest longitudinal bar
• 24 × diameter of stirrup bar
• 12 in. or 300mm
• Stirrups shall be spaced at no more than d/2
throughout the length of the member
• The potential plastic hinge region is assumed to extend a distance (2h) from the face of the support.
• Stirrups shall be provided at both ends of a member over a length equal to 2h from the face of the supporting
member toward mid-span.

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❖ Transverse Reinforcement: Frame columns
• L0 is assumed length of the anticipated plastic hinge region
• The length L0 shall not be less than the largest of
• Clear span/6.
• Maximum cross-sectional dimension of member.
• 18 in.
• Maximum tie spacing shall not exceed S0 over a length L0
measured from each joint face.
• Spacing S0 shall not exceed the smallest of:
• The first tie shall be located no farther than S0/2 from the joint face.
• Tie spacing outside of the length Lo shall not exceed 2S0.

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❖ General Requirements: JOINT
• Beam longitudinal reinforcement must extend to the
far of the joint core and must be developed in
tension.

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❖ Dimension limit: Frame Beams
SPECIAL CONCRETE MOMENT FRAMES (SMRF) SDC D-E-F
• The web width shall not be less than 0.3
times its height and 250 mm,
• The web width shall be greater than 3C2 and
C2+1.5C1
• Projection of the beam width beyond the
width of the supporting column on each side
shall not exceed the lesser of c2 and 0.75c1.
• The clear span of the beam shall not be less
than four times its effective depth.

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• The positive moment at the face of the
column must exceed one half the negative
moment strength provided at the face of the
supporting column.
• The minimum positive and negative
moments at mid-span must exceed one
fourth the maximum moment strength
provided at the face of the supporting
column.
• At least two bars at the top and bottom
faces of the beam must be continuous.

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• The required development length for straight bars are
multiples of the hooked bar development lengths in ACI
18.8.5.1:
• Minimum development length 2.5Ldh for bottom bars
• Minimum development length 3.25Ldh for top bars

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• The requirements for lap splices in beams of
special moment frames are given in ACI
18.6.3.3:
1. Hoop or spiral reinforcement spaced on
center no more than the lesser of d/4
and 4in. Must be provided over the lap
splice length.
2. The splice location shall not be less than
2h from the face of the support or from
the critical section of any plastic hinge.
3. Lap splices must not be located within
joints

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❖ Transversal Reinforcement: Frame Beams
• The calculated hoop spacing, s, within 2h must be
less than or equal to the smallest of the following:
• The center to center spacing of the transversely
supported longitudinal bars in beams must be less
than or equal to 14in

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❖ Dimension Limit: Frame Columns
• Shortest cross-sectional dimension
measured on a straight line passing through
the geometric centroid ≥12 in.
• Ratio of the shortest cross-sectional
dimension to the perpendicular dimension
≥0.4.

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• The splice location shall be limited to the center half of
the beam column to keep the splice outside of the
regions of the plastic hinges.
• the clear height of the column is greater than or equal
to 2.5 times the tension development length of the
bars.
• At least six longitudinal bars are required in columns
• The potential plastic hinge region is assumed to be
within a distance ( Lo ) from the face of the support.
• The minimum length of plastic hinge region ( Lo ) is
given as a function of the clear span of the column, the
dimensions of the section and 500 mm (18 in).
❖ Flexural Reinforcement: Frame Columns

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• The amount and spacing of hoops in the plastic hinge region
must extend through the joint as shown in figure.
• The spacing of hoops in the middle of the beam shall neither
exceed 6db nor 150 mm (6 in) and 5db.
❖ Transversal Reinforcement: Frame Columns

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STEEL MOMENT FRAME DESIGN REQUIREMENTS
AND ASSUMPTIONS
PART 2

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• steel moment frames have been in use for more than one hundred years.
• It was believed that:
1. Welded steel moment-frame buildings as being among the most
ductile systems contained in the building code.
2. The steel moment-frame buildings were essentially invulnerable to
earthquake-induced structural damage and thought that should such
damage occur, it would be limited to ductile yielding of members
and connections.
3. the typical connection employed in steel moment-frame
construction, was capable of developing large plastic rotations,
without significant strength degradation.
• Following the 1994 Northridge earthquake, engineers were surprised to
discover that more than 20 modern special steel moment frame structures
had experienced brittle fracturing of their welded beam-to-column
connections.
HISTORY OF SPECIAL MOMENT FRAME DEVELOPMENT
❖ History Of Steel Moment Frame

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• Many different types of fractures were also
discovered, the majority initiating where the
bottom beam flange joined the column flange.
• The SAC research, conducted at a cost of $12
million over eight years, resulted in the basis for
the current design provisions for moment frames
contained in AISC 341, AISC 358, and AWS D1.8.

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• Typically, but not always, fractures
initiated at the complete joint penetration
(CJP) weld between the beam bottom
flange and column flange (Figure 1-2).
• Once initiated, these fractures progressed
along a number of different paths,
depending on the individual joint
conditions.

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STEEL MOMENT FRAMES LIMITATIONS
1. ORDINARY MOMENT FRAMES
• AISC 341 §E1
• light, single-story structures and low-rise residential structures in all SDC
• permitted without restriction in SDC-A, B, and C
2. INTERMEDIATE MOMENT FRAMES
• AISC 341 §E2
• permitted without restriction in SDC- A, B, and C
• In SDC-D, are permitted for structures up to 35 feet (11 m) in height
• In SDC-E and F, are permitted for light, single-story structures only
3. STEEL SPECIAL MOMENT FRAMES
• AISC 341 §E3
• are permitted without restriction in all SDC
Recommendations
• are required as part of the seismic force-resisting system in SDC-D, E, and F for most structures exceeding
160 feet (49 m) in height
❖ Steel Moment Frames Types Limitations

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• Impractical to design structures to resist such severe but rare earthquakes
without damage.
• The building codes have adopted a design philosophy intended to provide
safety by minimizing the risk of collapse.
• Inelastic behavior is intended to be accommodated through the formation of plastic hinges in beams at
beam-column joints, as well as at column bases.
• Plastic hinging in beams and columns can be accompanied by local buckling of beam and column flanges or
webs.
• In recognition of the highly ductile inelastic behavior of panel zones and the ability of this behavior to
minimize the damage to beams, AISC341 encourages design to accommodate balanced yielding between
plastic hinge zones in beams and the panel zones.
STEEL MOMENT FRAME SEISMIC BEHAVIOR
0. Introduction

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• When buckling becomes excessive, strength loss and ultimately fractures
associated with low-cycle fatigue will occur.
• The use of highly compact sections for members intended to experience
hinging, minimizes the potential for strength loss and fracturing at deformation
levels likely to occur in response to MCER shaking.
1. Beam behavior
• Provision of lateral bracing in zones of
anticipated plastic hinging is required to
avoid lateral torsional buckling and the
strength loss associated with that behavior
mode.

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• Transfer the yield-level stresses and strains that develop in the beam to the column.
• Failure modes:
1. Fractures in or around welds
2. Fractures in highly strained base material
3. Fractures at weld access holes
4. Net section fractures at bolt holes
5. Shearing and tensile failures of bolts
6. Bolt bearing and block shear failures
• AISC 341 requires demonstration by conformance with prequalified details or through prototype testing:
1. at least +/- 0.04 radians of total rotation
2. No strength loss associated with these OR other failure modes when subjected to a specified
loading consisting of repeated cycles of increasing displacement.
2. Beam-to-column Connections

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• Consist of that portion of the column bounded by the
top and bottom beam flanges, resists significant
shear, tension, and compression forces from the
beams framing into the column.
• Potential failure modes include web compressive
buckling, web shear buckling, and, if doubler plates
are used to reinforce the panel zone, fracture at
welds.
• AISC 341 design procedures control these behaviors
through requirements for minimum shear strength,
provision of stiffener plates opposite beam flanges,
and control of welding details.
3. Joint Panel Zones

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• Doubler plate is needed to locally strengthen the column web.
• Adding doubler plates is expensive because of the significant shop
fabrication time that is needed to prepare the plate and weld it
into the column web.
• A rule of thumb that commonly applies for most typical moment
frame configurations, story heights of approximately 5m, and
beam spans of approximately 10 m, is as follows:
• if the designer can increase the weight per foot of the column by
less than 150 kg/m and avoid the need for doubler plates, the cost
of the frame will be reduced
4. Doubler plate

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• Except at restrained column bases, where plastic hinging is likely to
occur, columns are designed to behave in an essentially elastic
manner.
• This is accomplished through requirements that columns be stronger
in flexure than beams connected to the columns at the same joint.
• Columns can experience significant inelastic rotations in response to
severe shaking, resulting in excessive local buckling and lateral-
torsional buckling.
• To minimize this potential, columns must have adequate axial
strength, compactness, and lateral bracing to withstand the axial
forces associated with formation of full frame yield mechanisms.
5. Columns

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• In multistorey buildings, it is very convenient to splice the column
just above the floor .
• Multi-Storey structures generally require that the columns be
‘spliced’ in order to extend their length for the full height of the
structure.
• Splices may be either bolted or welded
• Potential failure modes at column splices are similar to those
enumerated for beam-tocolumn connections.
• the expected flexural strength of the smaller column cross
section be developed at column splices, either through the use
of complete joint penetration groove welds or through other
means that can provide similar strength.
6. Column Splices

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• Many steel special moment frame connections include a groove weld
between the beam flanges and the column flange.
• this joint is made with a single bevel weld that is detailed with weld
backing across the width of the flange, with the weld being made in
the flat position.
• The backing is typically a steel bar, 1 inch wide by 3/8 inch thick (10
mm).
• To accommodate this backing and to provide access for the welder to
make the weld at the bottom flange, a weld access hole is provided.
• Welds may be classified as either Complete Joint Penetration (CJP) or
Partial Joint Penetration (PJP).
• CJP welds extend completely through the thickness of components
joined.
• A CJP weld transmits the full load-carrying capacity of the structural
components joined, and is important for seismic safety.
8. Weld Access Holes

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• They do not have structural walls or diagonal braces.
• Impose smaller forces on foundations than do other structural systems.
• Provide architectural freedom in design, permitting open bays and
unobstructed view lines.
FEATURES OF STEEL MOMENT FRAME
1. Advantages
2. Disadvantages
• can be more costly to construct than braced frame or shear wall structures.
• The added cost results from the use of larger sections in moment frames
than is common in braced structures and more labor-intensive connections.
• drift-sensitive nonstructural components, such as cladding and glazing, can
experience more damage in these structures compared with other
structural types

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• The reduced seismic forces decreases progressively from OMRF to IMRF to
SMRF.
• The added level of detailing required for the better-performing systems can
significantly increase construction cost.
• lateral drift often control the selection of moment frame member sizes
• The reduced required strength associated with the more ductile systems do
not necessarily translate to savings in member sizes or frame weight.
• For tall buildings in SDC- D, E, and F, use dual systems, in which steel special
moment frames capable of providing at least 25% of the required lateral
strength are used in combination with shear walls or braced frames.
• The dual system allows economical control of lateral drift
Steel Moment Frames Features
FEATURES OF STEEL MOMENT FRAME

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FRAME PROPORTIONING
• factors affecting steel SMRF member size:
1. need to control design drifts below specified limits
2. need to avoid P-D instabilities
3. need to proportion structures to comply with the strong-column/weak-beam criteria of AISC 341 §E3.4a
• Use of deep section columns (ex: W24s, W36s, and built-up box sections)
1. economical choice
2. achievement of drift control
3. achievement strong column/weak-beam requirements
• deep wide flange sections, particularly those with lighter weights
1. susceptible to undesirable local and lateral-torsional buckling.
• The performance of deep column sections is the subject of ongoing research.
Steel Moment Frame Proportioning

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3.5 Connection Type Selection
• Prequalified connections have been demonstrated to be acceptable.
• connection prequalifications contained in the standard are acceptable to most
building officials. AISC 341
• Each prequalified connection has unique limits of applicability associated with
member type, depth, and weight.
• not every connection can be used in the same applications.
• Some types of connection:
1. The reduced beam section
2. end plate connection
3. welded unreinforced flange-welded web,
4. and double-tee connections.
AISC Prequalified Connections

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AISC Prequalified Connections

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COMPOSITE MOMENT FRAME
DESIGN REQUIREMENTS AND ASSUMPTIONS
PART 3

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• C-SMFs usually consist of CFT columns, wide flange steel beams, and rigid
beam-to-column connections.
• C-SMFs have been widely used around the world, for example, in
1. Two Union Square in Seattle, USA;
2. Shimizu Super High Rise in Tokyo, Japan
• C-SMFs have excellent earthquake resistance
• AISC 360-16 (2016c) provides design provisions for CFT members, including
• steel tube slenderness limits (i.e., limits on the steel tube width-to-
thickness ratio) to categorize CFT members into compact, noncompact,
and slender.
• design equations for estimating the strength of CFT members as
columns, beams, and beam-columns.
COMPOSITE SPECIAL MOMENT RESISTING FRAME
❖ Wide Flange Beam To Concrete-filled Steel Column Connections

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• Rigid beam-to-column moment connections should be designed to resist the forces
transferred from the connected members with negligible rotation.
• These forces produce shear in the panel zone, which is resisted by elements within the
panel zone (e.g., concrete infill, steel tube webs, and steel beam web).
• If the connection is unable to resist such shear, panel zone failure will occur because of
excessive shear deformations.
• Typical panel zone shear failure modes of composite beam-to-column connections
include
1. shear buckling of the steel tube webs
2. shear yielding of the beam web and steel tube webs
3. localized bearing failure in the concrete (Koester 2000)
4. diagonal shear cracks in the concrete (Ricles et al., 2004).
• The failure modes depend on the connection type.

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• AISC 341-16 (2016b) has the following requirements for
beam-to-column connections in C-SMFs:
1. Fully restrained (i.e., rigid)
2. Capable of accommodating a story drift angle of at
least 0.04 rad
3. Measured flexural resistance of the connection,
determined at the column face, shall equal at least to
0.80Mp at a story drift angle of 0.04 rad, where Mp is
the nominal plastic flexural strength of the connected
beam.

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• it consists of CFT columns, wide flange beams, tapered T-stubs, and high-
strength through bolts.
• The T-stub flange was attached to the column flange using pre-tensioned
high strength through bolts, and the T-stub stem was bolted or fillet welded
to the beam flange.
• the shear resistance of DST connections is mainly provided by the steel tube
webs and the concrete compression strut in the panel zone.
• Shear is transferred from the beam to CFT column through a shear tab
connection welded to the CFT column steel and bolted or welded to the
wide-flanged beam web.
❖ Double Split-tee Connections Dst Connection

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• Two types of DST connections were tested
by Ricles et al. (2004).
1. T-stub stem connected to beam
flange using high strength bolts
2. T-stub stem welded to the beam
flange.
• The test results indicated that both types
of connection could accommodate story
drift angles greater than 0.04 rad without
noticeable strength degradation.
• Therefore, these connections satisfy the
AISC 341-16 (2016b) requirements.

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• The governing limit states of DST connections are listed as follows, from most ductile
(desirable) to least ductile:
1. plastic hinge formation in beam,
2. gross yielding of the T-stem,
3. net section fracture of the T-stem,
4. compression of the T-stem caused by flexural buckling
5. weld fracture between the T-stem and the beam flanges,
6. prying of the T-stub flanges,
7. bolt fracture owing to the prying action of the T-stub flange,
8. panel zone shear failure.
• It should be designed and detailed so that plastic hinging occurs in the beam prior to
any of the other limit states.

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• The panel zone shear strength (Vn) of DST connections for rectangular CFT columns is
contributed from two parts
1. the shear strength of steel tube walls in the panel zone (Vtw)
2. the concrete compression strut (Vcs).
• The design equations proposed by Koester (2000) were used to calculate the panel zone
shear zone strength as follows:

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❖ DESIGN EXAMPLE FOR A WELDED DST CONNECTION
This example presents the design of a DST connection as an interior joint in a C-SMF.
o The wide flange beams are ASTM A992 (2015) wide flange sections (W24 × 76, Fy = 345 MPa, Fu = 448
MPa, Ry = 1.1).
o The beam depth (h) is 607 mm, flange width (bf) is 228 mm, flange thickness (tbf) is 17.3 mm, and web
thickness (tbw) is 11.2 mm.
o The CFT columns Hollow Steel Section (HSS) 406.4 × 406.4 × 19.1 made from ASTM A500 (2018) Grade B
steel (Fy = 317 MPa, Fu = 448 MPa) and filled with normal-weight, 55.2 MPa concrete (f ′c).
o A490 bolts with the diameter (dbt) of 25.4 mm are used.
o The distributed dead and live loads considered on the beams are 12.3 kN/m and 8.8 kN/m, respectively.
o The beam and column length are Lb = 9,144 mm and Lc = 3,810 mm, respectively.

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A 14-step design procedure is proposed as follows:
• Step 1: Calculate the flexural and shear demands for the connection at the face of the
column, and then use the flexural demand to calculate the beam flange forces in the
DST connection. These demands should include a material overstrength factor, Ry, and
a factor to account for peak connection strength, including strain hardening, local
restraint, additional reinforcement, and other connection conditions, Cpr.
• Step 2: Determine the length and size of welds required to resist the beam
• flange forces in the connection.
• Step 3: Estimate the flange force in the T-stub caused by the expected moment at the
face of the column.

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• Step 4: Size the T-stem based on limit states of gross section yielding, net section
fracture, and compression caused by flexural buckling.
• Step 5: Determine the size of the bolts connecting the T-stub flanges to the column.
• Step 6: Determine an initial configuration of the T-flange, including the layout of the
bolts, width of the T-stub flanges, and flange thickness to minimize or eliminate prying
action.
• Step 7: Select a W-shape or final sizes of built-up plates for dimensions of the T-stub.
• Step 8: Check the connection rotational stiffness to ensure that the connection is
classified as fully restrained.
• Step 9: Compute the maximum force in the T-stub using actual T-stub dimensions chosen
in Step 7.

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• Step 10: Back-check the strength of the weld with the actual flange force to ensure
the weld has adequate strength to resist the actual flange force.
• Step 11: Back-check the strength of the T-stem using the maximum beam flange
force calculated in Step 9. This includes gross section yielding, net section fracture,
and flexural buckling strengths of the T-stem.
• Step 12: Back-check the flange strength of the T-stub using the maximum beam
flange force calculated in Step 9.
• Step 13: Determine the configuration of the shear connection to the web
considering eccentric loading on the bolts.
• Step 14: Check panel zone strength using Equation (3-1).

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• Step 10: Back-check the strength of the weld with the actual flange force to ensure
the weld has adequate strength to resist the actual flange force.
• Step 11: Back-check the strength of the T-stem using the maximum beam flange
force calculated in Step 9. This includes gross section yielding, net section fracture,
and flexural buckling strengths of the T-stem.
• Step 12: Back-check the flange strength of the T-stub using the maximum beam
flange force calculated in Step 9.
• Step 13: Determine the configuration of the shear connection to the web
considering eccentric loading on the bolts.
• Step 14: Check panel zone strength using Equation (3-1).

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REFERENCES
✓ Design and detailing of reinforced concrete buildings based on ACI
✓ Earthquake engineering theory and implementation
✓ Wind and earthquake resistant building- structural analysis and design
✓ Seismic design of steel special moment frames a guide for practicing engineers
✓ Composite Special Moment Frames wide flange beam to concrete-filled steel column connections
✓ Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings
✓ AISC Live Webinar Series July 16, 2018
✓ AISC Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic
Applications

Moment Resisting Frame.pdf

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