2107.1 General. The design of masonry structures using allowable stress design shall comply with Section 2106 and the requirements of Chapters 1 and 2 of ACI 530/ASCE 5/TMS 402 except as modified by Sections 2107.2 through 2107.8.

2107.2 ACI 530/ASCE 5/TMS 402, Section 2.1.2, load combinations. Delete Section 2.1.2.1.

2107.3 ACI 530/ASCE 5/TMS 402, Section 2.1.3, design strength. Delete Sections 2.1.3.4 through 2.1.3.4.3.

2107.4 ACI 530/ASCE 5/TMS 402, Section 2.1.6, columns. Add the following text to Section 2.1.6:

2.1.6.6 Light-frame construction. Masonry columns used only to support light-frame roofs of carports, porches, sheds or similar structures with a maximum area of 450 square feet (41.8 m²) assigned to Seismic Design Category A, B or Care permitted to be designed and constructed as follows:

1. Concrete masonry materials shall be in accordance with Section 2103.1 of the International Building Code. Clay or shale masonry units shall be in accordance with Section 2103.2 of the International Building Code.

2. The nominal cross-sectional dimension of columns shall not be less than 8 inches (203 mm).

3. Columns shall be reinforced with not less than one No. 4 bar centered in each cell of the column.

4. Columns shall be grouted solid.

5. Columns shall not exceed 12 feet (3658 mm) in height.

6. Roofs shall be anchored to the columns. Such anchorage shall be capable of resisting the design loads specified in Chapter 16 of the International Building Code.

7. Where such columns are required to resist uplift loads, the columns shall be anchored to their footings with two No. 4 bars extending a minimum of 24 inches (610 mm) into the columns and bent horizontally a minimum of 15 inches (381 mm) in opposite directions into the footings. One of these bars is permitted to be the reinforcing bar specified in Item 3 above. The total weight of a column and its footing shall not be less than 1.5 times the design uplift load.

2107.5 ACI 530/ASCE 5/TMS 402, Section 2.1.10.7.1.1, lap splices. Modify Section 2.1.10.7.1.1 as follows:

2.1.10.7.1.1 The minimum length of lap splices for reinforcing bars in tension or compression, l_d, shall be

l_d = 0.002d_bf_s (Equation 21-2)

For SI: l_d = 0.29d_bf_s

but not less than 12 inches (305 mm). In no case shall the length of the lapped splice be less than 40 bar diameters.

where:

d_b = Diameter of reinforcement, inches (mm).

f_s = Computed stress in reinforcement due to design loads, psi (MPa).

In regions of moment where the design tensile stresses in the reinforcement are greater than 80 percent of the allowable steel tension stress, F_s, the lap length of splices shall be increased not less than 50 percent of the minimum required length. Other equivalent means of stress transfer to accomplish the same 50 percent increase shall be permitted. Where epoxy coated bars are used, lap length shall be increased by 50 percent.

2107.6 ACI 530/ASCE 5/TMS 402, Section 2.1.10.7, splices of reinforcement. Modify Section 2.1.10.7 as follows:

2.1.10.7 Splices of reinforcement. Lap splices, welded splices or mechanical splices are permitted in accordance with the provisions of this section. All welding shall conform to AWS D1.4. Reinforcement larger than No. 9 (M #29) shall be spliced using mechanical connections in accordance with Section 2.1.10.7.3.

2107.7 ACI 530/ASCE 5/TMS 402, Section 2.3.6, maximum bar size. Add the following to Chapter 2:

2.3.6 Maximum bar size. The bar diameter shall not exceed one-eighth of the nominal wall thickness and shall not exceed one-quarter of the least dimension of the cell, course or collar joint in which it is placed.

2107.8 ACI 530/ASCE 5/TMS 402, Section 2.3.7, maximum reinforcement percentage. Add the following text to Chapter 2:

2.3.7 Maximum reinforcement percentage. Special reinforced masonry shear walls having a shear span ratio, M/V_d, equal to or greater than 1.0 and having an axial load, P, greater than 0.05 f _mA_n that are subjected to in-plane forces shall have a maximum reinforcement ratio, ρ_max, not greater than that computed as follows:

        (Equation 21-3)

The maximum reinforcement ratio does not apply in the out-of-plane direction.