Info Shear Friction (Sliding Shear). To determine sliding shear resistance, we need to know the area of vertical reinforcement Avf crossing the assumed shear plane. For the example problem, we have not yet determined the vertical reinforcement in wall pier W1 across this plane which typically occurs at construction joints. Avf is calculated presently in the combined axial and flexural design part of this problem. It is equal to 12 #11 plus 8 #6, giving Avf = 22.24 in.2, which will be used to check the sliding shear. The sliding shear resistance is given by

Vn = Avffym

Using m = 1.0 l, where l = 1 for normal weight concrete, and Avf = 22.4 in.2,

Vn = 22.4 x 60 x 1 = 1334.4 kips > 300 kips OK Section 11.7.5 limits shear friction strength to 0.2 f'c Ac or 800 Ac. For the example wall pier,

n c c 1000

Vn = 800Ac = 800 x 16 x 8 x 12 = 1228 kips > 300 krps n c 1000

Therefore, wall pier W1 OK for sliding shear Longitudinal Reinforcement. Factored axial forces and moments for the design of W1 are as follows:

Pu = 1200 kips

Figure 4.51a shows the arrangement of vertical reinforcement in wall pier W1. Six #11 are placed near the wall boundary zones, with #6 @ 10 at each face in between the boundary elements. The printed output of the PCACOL screen is shown in Fig. 4.51b. The interaction point A, corresponding to Pu = 1200 kips, Mu = 2100 kips, is well within the interaction curve, justifying the design of W1 for the combined axial load and building moments.

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