Masonry Structures

Introduction : Masonry Construction Masonry : construction using building units (brick or stone) with or without mortar. Very ancient f...

Introduction : Masonry Construction

• Masonry : construction using building units (brick or stone) with or without mortar.


• Very ancient form of construction. Prior to 19th C, the dominant form of construction.


• Since about 8000 BC, 10000 years ago, masonry has had widespread use as a primary building material
  
  
  
  • Mesopotamia
  
  
  • Egyptians
  
  
  • Greeks and Romans
  
  
  • Europeans
  
  
  • Early America
  
  
  • Modern America


• Steel and concrete did not become legitimate building materials until the 1800’s

Development of Masonry Materials

• Stone


• Clay units
  
  
  
  • fired bricks 12,000 years
  
  
  • fired bricks  3000 B.C. Calcium silicate units 1800 A.D.


• Mortars
  
  
  
  • Clay
  
  
  • Clay-straw mixtures
  
  
  • Bitumen
  
  
  • Gypsum
  
  
  • Lime
  
  
  • Natural pozzolans
  
  
  • cement.

Advantages of Masonry Construction

• Relatively low cost, although bricklaying is expensive in terms of labour costs.


• Provides excellent:
  
  
  
  • weather protection
  
  
  • sound and thermal insulation
  
  
  • fire resistance.


• Flexible as an architectural medium (reasonably easy to incorporate holes, penetrations, etc into walls).

Disadvantages of Masonry Construction

• Labour intensive construction.


• Highly variable quality (a function of tradesman’s training and experience).


• Moisture penetration and thermal expansion


• Low strength-to-weight ratio


• Always on critical path for completion of load-bearing elements, unlike steel or concrete framed structures.


• Highly susceptible to cracking and movement.


• Low tensile strength when unreinforced

History of Masonry

• Some Well-Known Masonry Structures
  
  
  
  • Egyptian Pyramids (4000 - 2000 BC)
  
  
  • Greek Acropolis (450 - 400 BC)
  
  
  • Great Wall of China (200 BC ???)
  
  
  • Roman Coliseum (80 AD)
  
  
  • Notre Dame Cathedral (1100’s – 1200’s)
  
  
  • Mayan Ruins, Mexico (1400’s)
  
  
  • Taj Mahal (1600’s)
  
  
  • Palace of Versailles (1600’s)
  
  
  • The Alamo (1700’s)
  
  
  • Chicago Skyscrapers (1880’s)
  
  
  • Washington Monument (1884)

Historical Uses of Masonry

• Walls


• Pyramids


• Arches and Domes


• Cathedrals, Churches, and Temples


• Dams and Aqueducts


• Coliseums


• Towers


• Bridges


• Skyscrapers


• Schools


• Residential Structures (Apartment Buildings, etc.)


• Commercial Structures (Office Buildings, etc.)


• Retail Structures

Modern Structural Uses of Masonry

• Walls
  
  
  
  • Non-load bearing or load bearing
  
  
  • Lateral loads or no lateral loads
  
  
  • Reinforced or unreinforced
  
  
  • Single wythe or multiple wythe
  
  
  • Grouted or ungrouted


• Columns and Pilasters


• Beams and Lintels


• Arches and Domes

Types of Masonry Construction

• Unreinforced Masonry
  
  
  
  • Good for bearing walls (where compression predominates)
  
  
  • Little to no tensile resistance
  
  
  • Poor performance under lateral loads


• Reinforced Masonry
  
  
  
  • Similar to reinforced concrete
  
  
  • Steel reinforcing bars used through spaces in masonry units
  
  
  • Provides some tensile capacity
  
  
  • Improved performance under lateral loads


• Prestressed Masonry
  
  
  
  • Post-tensioned, similar to prestressed concrete
  
  
  • Significantly improved performance, as tension is reduced or eliminated altogether

Masonry Materials

• Masonry building unit


• Mortar


• Grout


• Reinforcement


• Accessories

Masonry Building Units: common types and sizes



Masonry Forms



Masonry Structural Elements



Masonry Structural Elements



Masonry Structural Elements

Columns and Pilasters (Isolated Piers)

• Isolated piers are one-dimensional, vertical load-bearing elements whose width and thickness do not exceed one-fifth of its height. They may be solid, hollow, unreinforced or reinforced

Diaphragm walls

Diaphragm walls consist of two leaves of masonry connected by header bricks or by cross walls to achieve composite action between the two leaves. They may be plain, reinforced or pre stressed.











Cavity Walls

Cavity walls consist of two leaves of masonry connected to each other by wall ties. The two leaves may or may not be of the same material and thickness. Generally, the cavity is open and the wall ties are spaced to prevent moisture penetration of the inner leaf from the outer leaf. The cavity may be filled with grout and reinforced to form a reinforced masonry wall.









Masonry Design Codes & Specifications

• MSJC (Masonry Standards Joint Committee) Code Building Code Requirements and Specification for Masonry Structures (and Commentaries)
  
  
  
  • ACI 530.1-02/ASCE 5-02/TMS 402-02  (Design code)
  
  
  • ACI 530.1-02/ASCE 6-02/TMS 602-02  (Specification)
  
  
  • First issued in 1988, then 1992, 1995, 1999, 2002 (approximate 3-year cycle)


• Model Building Codes
  
  
  
  • BOCA - Building Officials and Code Administrators (BOCA)
  
  
  • UBC - Uniform Building Code (ICBO)
  
  
  • SBC - Southern Building Code (SBCII)
  
  
  • IBC - International Building Code (ICC)

Masonry References

• Textbooks and Other Books
  
  
  
  • Masonry Structures - Behavior and Design (Drysdale, Hamid, and Baker), Prentice-Hall/TMS. 1999.
  
  
  • Design of Reinforced Masonry Structures (Taly), McGraw-Hill
  
  
  • Reinforced Masonry Design (Schneider and Dickey), Prentice-Hall
  
  
  • Masonry Designers’ Guide (Matthys, ed.), TMS
  
  
  • Concrete Masonry Handbook (Panarese, Kosmatka, and Randall), Portland Cement Association