twenty eight masonry construction: www.theeagle.com beams & - PowerPoint PPT Presentation

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 Lecture 28 ARCH 331

Office Hours link to posted schedule http://faculty.arch.tamu.edu/anichols/schedule/ Masonry Construction 2 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Design • 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 International Masonry Institute (Brian Trimble) Masonry Construction 3 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Beam & Wall Design • reinforcement increases capacity & ductility Masonry Construction 4 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Design • f s is not the yield stress • f m is the stress in the masonry STRAIN STRESS  m f m C m =f m b(kd)/2 kd d n.a. jd M t  s f s /n T s =A s f s A s grout unit A s   bd BIA Teknote 17 series Masonry Construction 5 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Materials • units – stone, brick, concrete block, clay tile www.GlenGerybrick.com National Concrete Masonry Association Masonry Construction 6 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Materials • mortar – water, masonry cement, sand, lime – types: • M higher strength – 2500 psi (ave.) National Concrete Masonry Association A • S medium high strength – 1800 psi O • N medium strength – 750 psi W • O medium low strength – 350 psi R • K low strength – 75 psi Masonry Construction 7 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Materials • rebar • grout – fills voids and fixes rebar • prisms – used to test strength, Ryan-Briggs Associates f  m • fire resistant National Concrete Masonry Association Masonry Construction 8 Architectural Structures S2018abn Lecture 28 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 Masonry Construction 9 Architectural Structures S2018abn Lecture 28 ARCH 331

Allowable Masonry Stresses • tension - unreinforced only Masonry Construction 10 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Walls tension normal to bed joints WALLS Not allowed in MSJC code tension parallel to bed joints weak units strong units Masonry Construction 11 Architectural Structures S2018abn Lecture 28 ARCH 331

Allowable Masonry Stresses • flexure – F b = 1/3 f’ m (unreinforced) – F b = 0.45 f’ m (reinforced) • shear, unreinforced masonry   120 psi – F v = 1 . 5 f m • shear, reinforced masonry – M/Vd  0.25:  F v = 3 0 . f m  – M/Vd  1.0: = 2 . 0 f F v m Masonry Construction 12 Architectural Structures S2018abn Lecture 28 ARCH 331

Allowable Reinforcement Stress • tension a) Grade 40 or 50 F s = 20 ksi b) Grade 60 F s = 32 ksi c) Wire joint F s = 30 ksi • *no allowed increase by 1/3 for combinations with wind & earthquake – did before 2011 MSJC code Masonry Construction 13 Architectural Structures S2018abn Lecture 28 ARCH 331

Reinforcement, M s C m =f m b(kd)/2 kd d n.a. jd t T s =A s f s A s grout kd   F=0: A f f b unit s s m 2   ρbd 2  M about C m : M A f jd jf s s s s if f s =F s (allowable) the moment capacity is limited by the steel MSJC: F s = 20 ksi, 24 ksi or 30 ksi by type Masonry Construction 14 Architectural Structures III S2018abn Lecture 23 ARCH 631

Reinforcement, M m C m =f m b(kd)/2 kd d n.a. jd t T s =A s f s A s grout kd   F=0: A f f b unit s s m 2 kd   2  M about T M f b jd 0 . 5 f bd jk s : m m m 2 if f s =F s (allowable) the moment capacity is limited by the steel MSJC F b =0.33f’ m Masonry Construction 15 Architectural Structures III S2018abn Lecture 23 ARCH 631

Masonry Lintels • distributed load – triangular or trapezoidal Masonry Construction 16 Architectural Structures S2018abn Lecture 28 ARCH 331

Strategy for RM Flexural Design • to size section and find reinforcement – find  b knowing f’ m and f y – size section for some  <  b • get k, j M  • 2 needs to be sized bd  jF for shear also s • get b & d in nice units M s  – size reinforcement (bar size & #): A F jd   – check design: s M A F jd M s s s M   f F b b 2 0 . 5 bd jk Masonry Construction 17 Architectural Structures S2018abn Lecture 28 ARCH 331

Ultimate Strength Design • LRFD • like reinforced concrete • useful when beam shear is high • improved inelastic  0.80 f’ m c 1 model 2 C – ex. earthquake loads  1 c T Masonry Construction 18 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Columns and Pilasters • must be reinforced Masonry Construction 19 Architectural Structures S2018abn Lecture 28 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 Masonry Construction 20 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Columns – allowable axial load   2     h         0 25 0 65 1 P . f A . A F a m n st s     140 r   h/r  99 2     70 r      0 25 0 65 P . f A . A F a m n st s   h h/r > 99 h = effective length r = radius of gyration A n = effective area of masonry A st = effective area of column reinforcement F s = allowable compressive stress in column reinforcement Masonry Construction 21 Architectural Structures S2018abn Lecture 28 ARCH 331

Masonry Walls (unreinforced) – allowable axial stresses   2 2     70 r h            0 . 25 F f F 0 . 25 f 1 a m   a m     h 140 r   h/r  99 h/r > 99 Masonry Construction 22 Architectural Structures S2018abn Lecture 28 ARCH 331

Design • masonry columns and walls (unreinforced) f f     a b f f F 1 . 0 and b a t F F a b   2   h      – h/r < 99   F 0 . 25 f 1 a m     140 r   2   70 r   – h/r > 99   F 0 . 25 f a m   h   F 0 . 3 3 f b m Masonry Construction 23 Architectural Structures S2018abn Lecture 28 ARCH 331

Design • masonry columns and walls - loading – wind loading P e w – eccentric axial load – “virtual” eccentricity, e 1 h P P e o e o w w M e  1 P V V M e 1 virtual eccentricity P P Masonry Construction 24 Architectural Structures S2018abn Lecture 28 ARCH 331

Design • masonry columns and walls – with rebar – wall reinforcement usually at center and ineffective in compression    f f F f F provided a b b a a BENDING STRESS AXIAL STRESS f m C m =f m b(kd)/2 f a = P/A d n.a. jd M t f s /n T s =A s f s A s grout unit     F P C T for equilibrium: m s Masonry Construction 25 Architectural Structures S2018abn Lecture 28 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 Masonry Construction 26 Architectural Structures S2018abn Lecture 28 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 Masonry Construction 27 Architectural Structures S2018abn Lecture 28 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 Masonry Construction 28 Architectural Structures S2018abn Lecture 28 ARCH 331

Final Exam Material • my list (continued): – foundations • types • sizing & structural design • overturning and sliding – design specifics • steel (ASD & LRFD) • concrete • wood • masonry Masonry Construction 29 Architectural Structures S2018abn Lecture 28 ARCH 331