Masonry Magazine August 1987 Page. 29
cracking or spalling of the brick when edge distances become small. To date, no research has been conducted in this area. Therefore, due to the lack of information, it is suggested that a minimum edge distance of 12 in. (300 mm) be maintained when expansion anchors are installed in brick masonry.
Through Bolts
There are no known published reports available addressing the strength characteristics of through bolts in brick masonry. However, based on the conservatism in the allowables for bent bar anchors and proprietary anchors, the allowable load equations should provide acceptable allowable load values for through bolts used in brick masonry. The embedment depth used to calculate the allowable load values should be taken as equal to the actual thickness of the masonry.
Current Codes and Standards
At the present time, one model code and one design standard contain provisions for anchor bolt design in brick masonry. The BIA Standard, Building Code Requirements for Engineered Brick Masonry, and the Uniform Building Code cover design allowables and embedment depths for anchors loaded in shear. There are no provisions for axial tensile loads or combined tension/shear loads in these documents. Tables 3 and 4 show the allowable shear loads and minimum embedment depths from the two documents. The values in Table 4(a) are based on rational analysis and in Table 4(b) on empirical analysis. As can be seen, the tables are very similar and are generally more conservative than the allowable shear loads obtained from Eqs. 5 and 6 for the same embedment depths (Table 5).
SUMMARY
This Technical Notes is the first in a series on brick masonry anchors, fasteners and ties. It covers anchor bolt types, detailing and allowable loads for anchor bolts in brick masonry. Other Technical Notes in this series will address brick masonry fasteners and ties.
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 herein should be used along with good technical judgment and an understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project designer, owner or both.
TABLE 5
Example Calculation of Allowable Shear on Anchors From ACI/ASCE 530*
| Anchor Diameter (in.) | Anchor Gross Cross-Sectional Area (in.²) | Embedded Depth (in.) | Allowable¹ Shear Load (lbs) |
|---|---|---|---|
| 1/4 | 0.049 | 4 | 210 |
| 3/8 | 0.110 | 4 | 470 |
| 1/2 | 0.196 | 4 | 840 |
| 5/8 | 0.307 | 4 | 1,320 |
| 3/4 | 0.442 | 5 | 1,910 |
| 7/8 | 0.601 | 6 | 2,060 |
| 1 | 0.785 | 7 | 2,200 |
| 1-1/8 | 0.994 | 8 | 2,340 |
*American Concrete Institute/American Society of Civil Engineers Committee 530 on Masonry Structures.
¹Assuming: f'm = 2,000 psi
ASTM A36 steel f, = 36 ksi
Edge Distance = 12 Bolt Diameters
REFERENCES
1. Manual of Steel Construction, 8th Edition, American Institute of Steel Construction, Inc., Chicago, Illinois, 1980.
2. Whitlock, A.R. and Brown, R.H., Strength of Anchor Bolts in Masonry, NSF Award No. PRF-7806095, "Cyclic Response of Masonry Anchor Bolts", August 1983.
3. Brown, R.H. and Dalrymple, G.A., Performance of Retrofit Embedments in Brick Masonry, NSF Award No. CEE-8217638, "Static and Cyclic Behavior of Masonry Retrofit Embedments (Earthquake Engineering)", Report No. 1, April 1985.
4. Hatzinikolas, M.; Lee, R.; Longworth, J. and Warwaruk, J., "Drilled-In Inserts in Masonry Construction", Alberta Masonry Institute, Edmonton, Alberta, Canada, October 1983.
5. Building Code Requirements for Engineered Brick Masonry, Brick Institute of America, McLean, Virginia, August 1969.
6. Uniform Building Code, International Conference of Building Officials, Whittier, California, 1985.
7. Technical Notes on Brick Construction 17 Revised, "Reinforced Brick Masonry, Part I of IV", Brick Institute of America, McLean, Virginia, October 1981.
8. Technical Notes on Brick Construction 41 Revised, "Hollow Brick Masonry-Introduction", Brick Institute of America, McLean, Virginia, 1983.
9. Specification for the Design and Construction of Load-Bearing Concrete Masonry, National Concrete Masonry Association, McLean, Virginia, April 1971.
10. The BOCA Basic/National Building Code, 9th Edition, Building Officials and Code Administrators, International, Country Club Hills, Illinois, 1984.
11. Standard Building Code, Southern Building Code Congress, International, Inc., Birmingham, Alabama, 1985.
12. Technical Notes on Brick Construction 7A Revised, "Water Resistance of Brick Masonry-Materials, Part II of III", Brick Institute of America, Reston, Virginia, 1985.