Laserfiche WebLink
<br /> <br /> <br /> <br /> <br /> <br />3rd & Broadway, Santa Ana, CA <br />Volume 2 - Structural Calculations June 17, 2024 | Project # S21043.00 <br /> pg. 93 <br />5.1.1.1 SHEAR DESIGN <br />Two categories of shear checks are presented to determine the necessary shear reinforcing. <br /> <br />One-Way Shear Check <br />One-way shear forces are obtained along the design strips normal to the wall faces for the minimum and <br />maximum demand of LRFD load combinations envelope. ACI 318-14 limits the shear stress, vn.max, to <br />2 √𝑓′𝑐 for concrete mats with no shear reinforcing. <br />The foundation mat has four varying depths: 7’-6”, 4’-6”, 4’-0” and 3’-0”. In SAFE, design strips are used <br />to determine the shear forces within each strip. The shear forces within each design strip are presented in <br />the following figures. <br />As per ACI 318-14, one-way shear is checked at a distance d (taken as 0.9*h) from the face of the wall. <br />The following figures show the strip shear forces at d from the wall, for the absolute maximum of the <br />LRFD enveloped forces in the X- and Y-directions. <br />As seen in the figures below, the mat foundation has adequate shear capacity for one -way shear without <br />the addition of vertical shear reinforcing everywhere except for the 7.5 ft mat under the core walls. By <br />studying the shear demand near core wall under governing load cases, vertical shear reinforcing of <br />#7@18” for Residential building and #6@18” for Hotel building are provided. <br />At thick mat foundation locations, minimum shear reinforcement is provided when the shear stress ratio <br />exceeds 1 √𝑓′𝑐 as recommended by the NEHRP Technical Brief No. 7. This is not a code requirement, <br />but is provided as best practice. This restriction on concrete contribution to shear is not applied to the <br />thinner mats which are at most 4.5 feet thick. <br /> <br /> <br /> <br />