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A RCHITECTURAL S TRUCTURES : F ORM, B EHAVIOR, AND D ESIGN A RCH 331 D R. A NNE N ICHOLS S PRING 2018 lecture twenty eight masonry construction: www.theeagle.com beams & columns Masonry Construction 1 Architectural Structures S2018abn

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SLIDE 1

S2018abn Masonry Construction 1 Lecture 28 Architectural Structures ARCH 331

lecture

twenty eight

masonry construction:

beams & columns

ARCHITECTURAL STRUCTURES: FORM, BEHAVIOR, AND DESIGN ARCH 331

  • DR. ANNE NICHOLS

SPRING 2018

www.theeagle.com

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SLIDE 2

S2018abn Masonry Construction 2 Lecture 28 Architectural Structures ARCH 331

Office Hours

link to posted schedule

http://faculty.arch.tamu.edu/anichols/schedule/

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SLIDE 3

S2018abn

  • Masonry Standards Joint Committee

– ACI, ASCE, TMS – ASD (+empirical)

  • linear-elastic stresses

– LRFD added in 2002 – referenced by IBC – unreinforced allows tension in flexure – reinforced - all tension in steel – walls are also in compression

Masonry Construction 3 Lecture 28 Architectural Structures ARCH 331

Masonry Design

International Masonry Institute (Brian Trimble)

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SLIDE 4

S2018abn Masonry Construction 4 Lecture 28 Architectural Structures ARCH 331

Masonry Beam & Wall Design

  • reinforcement increases capacity &

ductility

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SLIDE 5

S2018abn Masonry Construction 5 Lecture 28 Architectural Structures ARCH 331

Masonry Design

BIA Teknote 17 series

grout unit t d n.a. STRAIN STRESS As fm kd s M T

s=Asfs

fs/n m Cm=fmb(kd)/2 jd

bd A s  

  • fs is not the yield stress
  • fm is the stress in the masonry
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SLIDE 6

S2018abn Masonry Construction 6 Lecture 28 Architectural Structures ARCH 331

Masonry Materials

  • units

– stone, brick, concrete block, clay tile

www.GlenGerybrick.com National Concrete Masonry Association

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SLIDE 7

S2018abn Masonry Construction 7 Lecture 28 Architectural Structures ARCH 331

Masonry Materials

  • mortar

– water, masonry cement, sand, lime – types:

  • M

higher strength – 2500 psi (ave.)

  • S

medium high strength – 1800 psi

  • N

medium strength – 750 psi

  • O

medium low strength – 350 psi

  • K

low strength – 75 psi

W R A O

National Concrete Masonry Association

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SLIDE 8

S2018abn Masonry Construction 8 Lecture 28 Architectural Structures ARCH 331

Masonry Materials

  • rebar
  • grout

– fills voids and fixes rebar

  • prisms

– used to test strength, fm

  • fire resistant

Ryan-Briggs Associates National Concrete Masonry Association

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SLIDE 9

S2018abn Masonry Construction 9 Lecture 28 Architectural Structures ARCH 331

Masonry Materials

  • moisture resistance

– weathering index for brick – bond and detailing – expansion or shrinking from water

  • provide control joints
  • parapets, corners,

long walls

parapet with no control joint

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SLIDE 10

S2018abn Masonry Construction 10 Lecture 28 Architectural Structures ARCH 331

Allowable Masonry Stresses

  • tension - unreinforced only
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SLIDE 11

S2018abn Masonry Construction 11 Lecture 28 Architectural Structures ARCH 331

Masonry Walls

tension normal to bed joints tension parallel to bed joints Not allowed in MSJC code

strong units weak units

WALLS

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SLIDE 12

S2018abn Masonry Construction 12 Lecture 28 Architectural Structures ARCH 331

Allowable Masonry Stresses

  • flexure

– Fb = 1/3 f’m (unreinforced) – Fb = 0.45 f’m (reinforced)

  • shear, unreinforced masonry

– Fv =  120 psi

  • shear, reinforced masonry

– M/Vd  0.25: Fv = – M/Vd  1.0: Fv

=

m

f .  5 1

m

f .  3

m

f .  2

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SLIDE 13

S2018abn Masonry Construction 13 Lecture 28 Architectural Structures ARCH 331

Allowable Reinforcement Stress

  • tension

a) Grade 40 or 50 Fs = 20 ksi b) Grade 60 Fs = 32 ksi c) Wire joint Fs = 30 ksi

  • *no allowed increase by 1/3 for

combinations with wind & earthquake

– did before 2011 MSJC code

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SLIDE 14

S2018abn

MSJC: Fs = 20 ksi, 24 ksi or 30 ksi by type

Masonry Construction 14 Lecture 23 Architectural Structures III ARCH 631

Reinforcement, Ms

grout unit t d n.a. As T

s=Asfs

Cm=fmb(kd)/2 jd

F=0: M about Cm:

kd

2 kd b f f A

m s s

if fs=Fs (allowable) the moment capacity is limited by the steel

s 2 s s s

jf ρbd jd f A M  

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SLIDE 15

S2018abn Masonry Construction 15 Lecture 23 Architectural Structures III ARCH 631

Reinforcement, Mm

grout unit t d n.a. As T

s=Asfs

Cm=fmb(kd)/2 jd

F=0:

jk bd f 5 . jd 2 kd b f M

2 m m m

 

kd

MSJC Fb =0.33f’m

2 kd b f f A

m s s

if fs=Fs (allowable) the moment capacity is limited by the steel M about T

s:

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SLIDE 16

S2018abn Masonry Construction 16 Lecture 28 Architectural Structures ARCH 331

Masonry Lintels

  • distributed load

– triangular or trapezoidal

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SLIDE 17

S2018abn Masonry Construction 17 Lecture 28 Architectural Structures ARCH 331

Strategy for RM Flexural Design

  • to size section and find reinforcement

– find b knowing f’m and fy – size section for some  < b

  • get k, j
  • get b & d in nice units

– size reinforcement (bar size & #): – check design:

s

jF M bd  

2

needs to be sized for shear also

jd F M A

s s  b b s s s

F jk bd . M f M jd F A M    

2

5

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SLIDE 18

S2018abn Masonry Construction 18 Lecture 28 Architectural Structures ARCH 331

Ultimate Strength Design

  • LRFD
  • like reinforced concrete
  • useful when beam shear is high
  • improved inelastic

model

– ex. earthquake loads

T 1c 0.80f’m C

2 c

1

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SLIDE 19

S2018abn Masonry Construction 19 Lecture 28 Architectural Structures ARCH 331

Masonry Columns and Pilasters

  • must be reinforced
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SLIDE 20

S2018abn Masonry Construction 20 Lecture 28 Architectural Structures ARCH 331

Masonry Columns and Pilasters

  • considered a column when

b/t<3 and h/t>4

  • b is width of “wall”
  • t is thickness of “wall”
  • slender is

– 8” one side – h/t  25

  • needs ties
  • eccentricity may be required
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SLIDE 21

S2018abn Masonry Construction 21 Lecture 28 Architectural Structures ARCH 331

Masonry Columns

– allowable axial load

h/r  99 h/r > 99

h = effective length r = radius of gyration An = effective area of masonry Ast = effective area of column reinforcement Fs = allowable compressive stress in column reinforcement

 

                 

2

140 1 65 25 r h F A . A f . P

s st n m a

 

2

70 65 25          h r F A . A f . P

s st n m a

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SLIDE 22

S2018abn Masonry Construction 22 Lecture 28 Architectural Structures ARCH 331

Masonry Walls (unreinforced)

– allowable axial stresses

h/r  99 h/r > 99

                

2

140 1 25 . r h f F

m a 2

70 25 .         h r f F

m a

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SLIDE 23

S2018abn Masonry Construction 23 Lecture 28 Architectural Structures ARCH 331

. 1  

b b a a

F f F f

Design

  • masonry columns and walls

– h/r < 99 – h/r > 99

                

2

140 1 25 . r h f F

m a 2

70 25 .         h r f F

m a

m b

f F   3 3 . and

t a b

F f f  

(unreinforced)

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SLIDE 24

S2018abn Masonry Construction 24 Lecture 28 Architectural Structures ARCH 331

Design

  • masonry columns and walls - loading

– wind loading – eccentric axial load – “virtual” eccentricity, e1

h P e w

eo P M V P w w eo P V P e1 P M e 

1

virtual eccentricity

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SLIDE 25

S2018abn Masonry Construction 25 Lecture 28 Architectural Structures ARCH 331

Design

  • masonry columns and walls – with rebar

– wall reinforcement usually at center and ineffective in compression

b b a

F f f  

provided

a a

F f 

grout unit t d n.a. BENDING STRESS As fm M T

s=Asfs

fs/n Cm=fmb(kd)/2 jd fa = P/A AXIAL STRESS

  

s m

T C P F for equilibrium:

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SLIDE 26

S2018abn Masonry Construction 26 Lecture 28 Architectural Structures ARCH 331

Design Steps Knowing Loads

  • 1. assume limiting stress
  • buckling, axial stress,

combined stress

  • 2. solve for r, A or S
  • 3. pick trial section
  • 4. analyze stresses
  • 5. section ok?
  • 6. stop when section is ok
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SLIDE 27

S2018abn Masonry Construction 27 Lecture 28 Architectural Structures ARCH 331

Final Exam Material

  • my list:

– systems

  • components & levels
  • design considerations

– equilibrium - F & M

  • supports, trusses, cables, beams, pinned frames,

rigid frames

– materials

  • strain & stress (E), temperature, constraints
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SLIDE 28

S2018abn Masonry Construction 28 Lecture 28 Architectural Structures ARCH 331

Final Exam Material

  • my list (continue):

– beams

  • distributed loads, tributary width, V&M,

stresses, design, section properties (I & S), pitch, deflection

– columns

  • stresses, design, section properties (I & r)

– frames

  • P, V & M, P-, effective length with joint

stiffness, connection design, tension member design

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SLIDE 29

S2018abn Masonry Construction 29 Lecture 28 Architectural Structures ARCH 331

Final Exam Material

  • my list (continued):

– foundations

  • types
  • sizing & structural design
  • overturning and sliding

– design specifics

  • steel (ASD & LRFD)
  • concrete
  • wood
  • masonry