Training 10: Worked calculation, masonry
A reinforced CMU lintel over an 8 ft opening. New calculation, Masonry lintel and beam.
Inputs:
| Input | Value |
|---|---|
| Wall | 8 in. CMU, f'm = 2,000 psi, Type M or S mortar (the defaults) |
| Lintel | 2 courses |
| Opening | 8 ft, bearing 8 in. each side |
| Bottom bars | 2 #5, embedment past the opening 32 in. |
| Applied loads | D = 400 plf, Lr = 300 plf, plus the wall above and self-weight (defaults) |
2 #5: not adequate, and not for strength #
The moment strength is ample, 31.0 kip-ft, yet the status is Not adequate. The failing check is Bottom bar embedment ≥ ld (TMS 402-22 6.1.6.3.1): 38.932 in. needed and 32 in. provided, a ratio of 1.217.
This is why you read the rows and not only the governing strength check.
2 #4: adequate #
Change the bars to 2 #4.
8 in. CMU lintel, 2 courses, 8 ft opening, Adequate. The effective span is 8.67 ft.
| Check | Clause | Required | Available | Ratio |
|---|---|---|---|---|
| Flexural strength (positive moment) | TMS 402-22 9.3.2 | 13.7 kip-ft | 21.0 kip-ft | 0.656 |
| Shear strength | TMS 402-22 9.3.3.1.2 | 5.1 kips | 7.7 kips | 0.656 |
| Deflection (service) | TMS 402-22 4.6, 5.3.1.6 | 0.069 in | 0.173 in | 0.397 |
The factored reaction at each end is 6.3 kips. Take that to the bearing below.
A plain word on the code basis. TMS 402-22 itself is not on hand: the masonry types are built on TMS 402-13 wording and the TMS cross-reference, as the chapter records. References marked (to confirm against the code text) in the checks are clauses not yet confirmed against the 2022 text. Read those yourself until they are cleared.