Masonry infill
One concrete or clay masonry panel in a bounding frame, participating as an equivalent diagonal strut, or isolated and carrying only out-of-plane load. The basis is the infill chapter of the TMS code, read here as TMS 402-13 Appendix B and CMHA TEK 14-23. TMS 402-22 moved it to Chapter 12, which is not on disk for this calculation: a TMS summary says virtually no changes, and it is marked (to confirm against the code text).
Inputs of the masonry infill #
- Infill: participating, or non-participating. A participating infill must fill the frame with no openings. A partial infill, or one with openings, cannot be part of the lateral system (B.1.5) and is entered as non-participating; its effect on the frame stays yours to consider.
- Height, length, nominal thickness, fully grouted: hollow units take the two face shells as net thickness.
- f'm, Em: Em is an input, 900 f'm for concrete masonry and 700 f'm for clay.
- Bond and grouting: sets the line of the bed joint shear strength in 9.2.6. Net bedded area per foot: 30 in.² for 8 in. units on face shell bedding.
- Bounding frame: E and I of a bounding column and beam, for bending in the plane of the infill. Average different columns; on a single story use the beam above.
- At the top of the infill: tight, gap under 3/8 in. or not sized for the displacement (strength and stiffness are halved, B.3.1.2.1), or sized to pass no force (refused: non-participating). A gap at the sides removes the horizontal arch; a top gap the vertical one.
- Strut thickness: the code text at B.3.4.1 reads specified thickness, and that is prefilled. TEK 14-23's worked example uses net thickness, which gives about a third of the stiffness on hollow units. The option is yours to decide, and the Eq. B-2a stiffness parameter uses net thickness in both.
- Loads: factored shear on this panel, from your frame analysis; bed joint compression; factored out-of-plane pressure. This is strength design only, as the code says.
- Connectors and joints: spacing, at most 4 ft; on a non-participating infill, the joint width and the frame's design displacement.
Auto-design varies the nominal thickness, thinnest first, then full grouting. Height, length, frame, loads and f'm are kept.
Checks performed #
| Check | Basis |
|---|---|
| Height to thickness at most 30 | B.3.1.1 |
| In-plane shear: least of corner crushing, the strut force at 1 in. of racking, bed joint shear over 1.5, φ = 0.60 | B.3.4.3, Eqs. B-3, B-4; 9.2.6 |
| Out-of-plane arching, φ = 0.60 | B.3.6, Eqs. B-7a, B-8, B-9, thickness at most a height over 8 |
| Connector spacing | B.2.2.4, B.3.3.3 |
| Isolation joint: at least 3/8 in. and the frame's displacement | B.2.1.2 |
| Forces for the bounding frame (a note) | B.3.5 |
Limitations of the masonry infill #
- The bounding frame is not analysed or designed. Enter the shear on this panel from your own analysis of a frame with the strut in it. The note lists the strut force, the column and beam shear to add and, as a pin-jointed frame, the axial forces.
- A non-participating panel's own bending between connectors is not here: use Unreinforced masonry wall or Masonry wall. Connector design is yours; the force is listed.
- AAC infill has its own equations and is not offered.
- R and Cd for this hybrid system are not in ASCE 7's table. The Commentary recommends the smaller of the frame's and the masonry's, which is yours to decide.
- Code numbers are 402-13's. Confirm them against 402-22 Chapter 12.
Verification examples #
Verification status: 19 values compared in 4 examples (4 published, 0 hand calculations from the cited equations): 19 within tolerance, 0 recorded deviations. Code basis: written from an older edition, with the differences noted. Not yet compared line by line with the target edition.
| Source | What |
|---|---|
| CMHA TEK 14-23, Example 1, pp. 3-6 | λ 0.0392, stiffness 56,030 lb/in., the bed joint lines, Vn 22,500 lb, φVn 13,500 lb (with the net thickness option, as the example) |
| CMHA TEK 14-23, Example 2, pp. 6-7 | αarch 21, βarch 10, qn 41.4 psf, φqn 24.8 psf |
| C. J. Tucker, "So, You Need to Design a Masonry Infill", STRUCTURE magazine | 32 ft by 14 ft panel: Eq. B-3 30,000 lb, strut at 1 in. 70,340 lb, 9.2.6 lines, φVn 18,000 lb, φqn 37.6 psf |
No clay masonry example, no fully grouted example and no example with gaps was on disk: those paths are by hand in the behaviour tests. TMS's Masonry Designers' Guide Examples 15.2-1 and -2 are to be added when it is bought.