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Correspondence (2) i 92 - ov 76 #/. *-- w . S. iiii Fi . 6' ' ' .1)- if A.G i JOB MEMORANDUM 16125 S W. BOONS FERRY ROAD LAME OSWEGO. OREGON 97034 5031635-0784 TO: Mr. Don Foster, AIA May Design and Construction FROM: Steve Entenman, PE Froelich Consulting Engineers 16325 SW Boones Ferry Rd #104 Lake Oswego, OR 97035 DATE: 26 April 1993 RE: Meier & Frank Washington Square 93 -94 Remodel Remodel of Existg Bracing Along Line M Job No. 130.1 -93 MESSAGE: A meeting was held today, 26 April 1993, to discuss design alternatives regarding the existing bracing along grid line M that the May Company is proposing to remove. Attendees included Frank Ellis (EEA), Jim Jaqua (City of Tigard), and the writer. Items discussed and decisions made follow. 1. Existing chevron bracing in the east most four bays along grid line M from the second floor level to the roof structure is proposed to be removed to allow the remodel of existing spaces to be additional retail. The existing bracing fastens to the top of the columns at the roof beam and runs diagonally down to the second floor level at mid -point between each column. 2. A scheme was presented earlier to provide horizontal bracing in the plane of the roof from line M south to the perimeter walls which would serve as shear walls. This scheme would change the reaction of the building under lateral loading. When stronger, more ductile elements are installed as required by code, these elements will draw more lateral loading to them and change the structural response of the building to lateral loads. We would be creating conditions of overloading on some 1j existing structural components and may cause failure of the system. It was decided not to pursue this scheme further. 3. Another scheme was introduced that would remodel the existing bracing along line M and keep the lateral load resisting elements along the same line. Advantages include: A) remodeled bracing along line M would be the same stiffness and more ductile than the existing, which would absorb more lateral loading; B) the existing roof diaphragm will act and react the same as before; and C) the second floor concrete diaphragm would be loaded from above In the same manner as previously. 4. The remodeled bracing would conform to seismic zone 3 requirements and designed for seismic zone 2 loads since that is what the existing roof diaphragm, the second floor diaphragm, and the lower level shear walls are designed for. Jim Jaqua agreed with our approach and stated that we should proceed with our design based on the remodel of the bracing system along line M. Short of upgrading the whole of the original building to seismic zone 3, he agreed this was the most prudent solution. 5. We may have to install bracing above the 10' -6" ceiling line all along line M and reinforce each column, but would depend on our computer analysis as we match up the stiffness of the existing bracing with that of the remodeled. The preliminary layout as shown in the attached sketch depicts our intent and Jim Jaqua's understanding of our approach. Please call as soon as possible if you take any exception, or if you have any questions. We will proceed with our design of the remodeled bracing based on these agreements and approvals as soon as practicable. cc: File Frank Ellis (EEA) Jim Jaqua (City of Tigard) o ® ® o.0 o ® o If 0 7 ® . _ _. 0 • ._ _ © • _ .. . .. .. ___ _ ..._.._ .._. . .. © - - -- - -- -- - - - O . O AS �..w.P{nds 0 < @ O E„VJf'b .......F v.."....AS,.., Aora 7 •rs SA4td 0 1 1 E ® Wi..l Da."''.'?. Ato.t. 0 /Aw.e. 'brifT -.J en4 h4 I t- r' . bcc.A.'asv 00•15.. © - vaw.b sr.w.r O - - -- -- - - - - - - - - - - - - -- -- ---- -- . O - . r Z w p.o •2 co... eye.... 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Merlag„,, ' + FRA444... 1106 St9LUNaer t I p1.4.1 E...L.. A-CA A" / 1 \ I I .. a \ A\ / Frae aaraa4 C0 P4re er■frard.04 si-E-•. OF e-'s I 5.1" IL 242-4. 1 rJas. 41 /61)9P zepA oo to g3aO A A , S Re( F - V ii)k° JOB MEMORANDUM 16325 &W. BOONES FERRY ROAD LA11E OSINEGO, OREGON 97034 5031636-0784 TO: Mr. Frank Ellis / Mr. Martin Hanson Ellis Eslick Architects FROM: Steve Entenman Froelich Consulting Engineers 16325 SW Boones Ferry Rd #104 Lake Oswego, OR 97035 DATE: 19 March 1993 RE: Lateral Load Design Criteria Meier & Frank 1993 Additions Job No. 130.0 -93 MESSAGE: To confirm our telecon of Wed 17 March 1993 with Martin, we offer the following: It is our understanding that the City of Tigard has ruled and authorized us to proceed with the lateral design of the 1993 North Addition under 1991 UBC requirements using Seismic Zone 3 criteria. The 1984 North Addition was designed for Seismic Zone 2 and will have to be upgraded. The original building was designed under previous code and Seismic Zone 2 requirements. As you know, the 1984 Addition included providing substantial first story shear walls along existing building grid line A that brace not only the addition structure but also a significant portion of the original building. The City of Tigard is not requiring that any of the existing building be brought up to current Zone 3 requirements, even with the major revisions and modifications planned for the second story shear walls along grid line A. It will be our intent, then, to design the revised second story shear walls to withstand at least the same forces as the present second story walls with the earlier design requirements and with the additional loads from the proposed addition as noted above. It is important to us that Ellis Eslick Architects and Meier & Frank understand that under this design criteria, the Washington Square M & F building will not have a lateral load design that is consistent. The North Additions will be designed under more stringent requirements than the original building and theoretically withstand higher seismic forces. We will comply with the City of Tigard ruling. Please call if have any questions or take any exceptions. cc Mr. Chris Hampson, M & F Mr. Jim Jaqua, City of Tigard