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Properties Of Wall Assemblies Structural
Masonry System Data For Architects
By Clark Johnson, PE
1) General
2) Typical Structural Notes
3) Wall Reinforcement
4) Estimating Curves For Slender Walls
5) Lintels
6) Wall Anchors
1. General
Architects need preliminary data prior to engaging a structural engineer. They need to know basic things as preliminary wall thickness, reinforcement, details, etc. The information that follows is intended as a first approximation only and is not a final design.
Final design computations must be prepared by a qualified structural design professional so that all factors of a particular project are considered.
2. Typical Structural Notes
2.1. Typical structural notes for 8' CMU masonry walls.
a. Concrete masonry units grade N, per ASTM 090-71, laid up in running bond. Design f'm = 1350 PSI.
b. Mortar type S, f'c = 1800 PSI at 28 days.
1 part portland cement, 1/2 part hydrated lime, 4-1/2 parts aggregate.
c. Grout f'c = 2000 PSI at 28 days. Solid grout all cells containing reinforcement or inserts.
d. Reinforcement, unless specifically shown otherwise, shall be:
1. 1 -#5 vertical @ 48" oc. Add 1 -#5 vertical each side of openings; at wall corners and intersections, at free ends of walls, and each side of control joints. Use prefabricated wire positioners at bottom, top, and 192 bar diameters oc. maximum to hold vertical bars in position.
2. 2 - #4 horizontal @ 48 oc. Add 2 - #4 horizontal continuous at all floor and roof lines, and at tops of walls. Provide corner bars at wall intersections.
e. Lap splice bars 40 bar diameters at splice points.
2.2. Typical structural notes for 8 Hollow Clay Brick masonry walls.
a. Hollow clay brick masonry units grade SW, per ASTM 0652-75, laid up in running bond. Design f'm=2600 PSI.
b. through. e - same as for CMU wall above.
3.1. Wall reinforcement must equal at least 0.002 times the gross cross-sectional area of the wall for the sum of the areas of horizontal and vertical reinforcement. The minimum area of reinforcement in either direction must not be less than 0.0007 times the gross cross-sectional area of the wall.
3.2. Wall reinforcement at corners, intersections and ends. Intersecting walls must be properly tied together. Typical details are as per details 3.2.
3.3. Control joints require vertical reinforcement at each side of the vertical control joint. Horizontal chord reinforcement must run continuous through the vertical control joint at floor and roof levels, in order to resist lateral loads caused by wind and earthquake. See details 3.3.
3.4. Retaining wails made of masonry offer an inexpensive alternative to concrete due to high forming costs for concrete. Special inspection is required if the full allowable strength of the masonry is used. Cantilever retaining walls must be designed for: masonry and steel stresses in the wall and footing, overturning stability, sliding stability and soil pressure. ref. detail 3.4.
3.5. Freestanding fences are designed to resist lateral loads caused by wind and earthquake. A first approximation for the footing width is 30% of the distance from the bottom of the footing to the top of the wall. Fences must be designed for: masonry and steel stresses in the wall and footing, overturning stability, and soil pressure. ref. detail 3.5.
3.6. Two wythe brick wall reinforcement is designed the same as other types of masonry walls with special care to reinforcement cover and clearances. ref. detail 3.6.
The NW Masonry Guide Table of Contents
Masonry Institute of Washington
Washington State Conference of Mason Contractors
