3000 ROCKEFELLER AVE ADMIN BLDG WEST 2022-05-13

Mr. Bob Egleston August 2, 2018 'Page 3 Structure Comment 15. This comment does not appear to be addressed by the submitted calculations as indicated. Please specify the pertinent calculation pages for each comment. Original Comment 15a: Additional documentation for the design of the shear wall foundation at Grid C18- 7 7 should be submitted for review. See IBC Section 1604.4. The following comments should be addressed. - a. The foundation appears to be designed as a monolithic element. However, the foundation encases three existing gravity footings. The foundation should be evaluated considering its actual geometry, including discontinuities in its structure. Response: See attached supplemental calculations (Shear Wall Foundations), b. The foundation is anticipated to have rigid bearing zones at the ends due to the micropiles. The foundation shall be designed as needed by analysis to span between the ends and distribute vertical loads to the piles. Response: See attached supplemental calculations (Sheor Wall Foundations). C. The load path between the shear wall and the continuous sides of the foundation shall be substantiated Response.: See attached supplemental calculations (Shear Wall Foundations). MAGNUSSON KLEMENCIC ASSOCIATES MKA Response At locations where the foundation encases existing footings, the foundation region above the existing footing was designed as a pile cap with strut and tie modeling in order to account for the discontinuities (See previously submitted calculation pages 1061-1062). The foundation elements were designed with the micropiles accounted for as point supports with an assigned spring constant matching the recommendations of the geotechnical engineer. See previously submitted calculations sheet 1004 for geotechnical engineer's recommendation for micropile spring stiffness. Foundation bearing stresses are distributed to the micropiles and surrounding soil based on relative stiffness and the concrete foundation design is consistent with this distribution. See previously submitted calculation sheet 1011 for the corresponding point spring stiffness used in the SAFE model. See previously submitted calculations (pages 1061-1062). The portion of the new footing above the existing footing was designed as a shallow depth pile cap. Bottom steel was added on the previously submitted drawings to "bridge' over the existing footing. The bottom reinforcement on either side of the existing footing runs continuous over the entire length of the new footing and satisfies the demands determined from the SAFE model.