Masonry Magazine August 1992 Page. 34
The allowable flexural tensile stress, F₁
The allowable flexural tensile stress, F₁, is determined from Table 2. The percent of grouted to ungrouted area is used to interpolate between 68 psi and 25 psi for fully grouted and ungrouted hollow unit masonry, respectively, giving an allowable flexural tensile stress:
F₁4/3 [25 psi + (68 psi 25 psi) (# of grouted cores)/(# of cores)]
4/3 [25 psi + (43 psi)(4/22)] 44 psi <55 psi
Therefore, try partial grouting to increase F₁. If 4 more cells are grouted, the flexural tensile stress, f, reduces to 49 psi, and the allowable flexural tensile stress, Fr, equals 54 psi 49 psi, OK.
Step 9: Sliding and overturning resistance of the caisson is a function of the lateral soil pressure and is beyond the scope of this Technical Notes.
SUMMARY
This Technical Notes discusses the structural design of brick masonry noise barrier walls. Design procedures are given following working stress analysis provided in the ACI/ASCE/TMS standard. Example designs are presented for recommended design of pier and panel, pilaster and panel and cantilever brick noise barrier walls.
The information and suggestions contained in this Technical Notes are based on the available data and the experience of the technical staff of the Brick Institute of America. The information and recommendations contained in this publication must be used in conjunction with good engineering judgment and a basic understanding of the properties of brick masonry and related construction materials. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project designer and owner.
REFERENCES
1. Anand, S.C., Brick Masonry Noise Barrier Walls, A Refined Structural Analysis of Wall Panel for Pier/Panel Case, Submitted to the Brick Institute of America, December 1991, 16 pp.
2. Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-92) and Specifications for Masonry Structures (ACI 530.1/ASCE 6/TMS 602-92), American Concrete Institute, Detroit, MI, 1992.
3. Guide Specifications for Structural Design of Sound Barriers, American Association of State Highway and Transportation Officials, Washington, D.C., 1989.
4. Load and Resistance Factor Design Manual of Steel Construction-First Edition, American Institute of Steel Construction, Chicago, IL, 1986.
5. Minimum Design Loads for Buildings and Other Structures (ASCE 7-88), American Society of Civil Engineers, New York, NY, 1990.
6. Noise Barrier Design Handbook, (Report No. FHWA-RD-76-58), United States Department of Transportation, Federal Highway Administration, Washington, D.C., 1976.
7. Technical Notes on Brick Construction 3, "Building Code Requirements for Masonry Structures ACI 530/ASCE 5 and Specifications for Masonry Structures ACI 530.1/ASCE 6," February 1990.
8. Technical Notes on Brick Construction 45, "Brick Masonry Noise Barrier Walls-Introduction," February 1991.
9. Uniform Building Code, 1991 Edition, International Conference of Building Officials, Whittier, California, 1991.