16 ATTACHMENTS - Laserfiche WebLink

Project No. JB-569 20 June 2006 Revised 18 October 2006 Page 10 The gradient of the exposed outboard surface of the fill must not exceed 2H:1 V. Additional recommendations may be made for fill slope construction depending on the soil conditions encountered. Grading should be in accordance with the Vineyard Avenue Corridor Specific Plan. 6.2 Foundations 6.2.1 Drilled Pier and Grade Beam Foundation System Piers should be designed according to the criteria in Table 3. The load-carrying capacity of the upper 2 feet of soil should be neglected in determining the allowable pier capacity. To reduce the potential for differential settlement, we recommend that all piers be cleaned of slough and loose material prior to placing steel reinforcement and concrete. The piers and grade beams should contain steel reinforcement over their entire length with reinforcement as directed by the Project Structural Engineer according to applicable UBC or American Concrete Institute standards. In no case, however, should the grade beams contain less than two No. 4 reinforcing bars (or equivalent steel areal in both the top and bottom of each beam, and the piers should have no less than two No. 4 reinforcing bars. The reinforcement steel for the pier should be tied into the top steel of the grade beam. Due to the moderate to high expansion potential of the site soil, we recommend the exterior grade beams be designed to resist a uniform upward pressure of 2,000 pounds per square foot. As an alternate, a void of approximately 4-inches should be provided below the bottom of the grade beam and the subgrade. The void may be replaced with a compressible material approved by our representative. If raising the grade beam is not desired, the beams may consist of a "knife-edge" formed at the bottoms of the beams with at least 30 degrees from horizontal. For "knife-edged" beams, the uplift pressures should be halved for design purposes. Korbmacher Engineering, Inc.