ADDENDA #9- RFP Sylvania CC building Re-Roof Progressive Design Build for Sylvania Campus CC Building Re-Roof Services

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1 ADDENDA #9- RFP Sylvania CC building Re-Roof Progressive Design Build for Sylvania Campus CC Building Re-Roof Services Addenda Dated: 01/25/2019 PURPOSE: The purpose of this Addenda #9 is to provide a copy of the supplemental information related to Seismic Work Clarifications, listed as Appendix L on the RFP. The document follows this cover sheet and is attached. End of Cover Sheet for Addenda #9

2 January 25, 2019 Ms. Krista Phillips, Managing Architect Portland Community College 9700 SW Capitol Hwy, Suite 260 Portland, OR Re: PCC Sylvania CC Building Seismic Work Clarifications Dear Krista: As you requested, I am writing this letter to clarify the extent of seismic retrofit work that has been completed as well as any outstanding known seismic deficiencies that have not been addressed at the PCC Sylvania CC building. This letter also discusses how the remaining deficiencies are related to the current building re-roofing project. In 2011, KPFF and GBD Architects performed seismic evaluations of several of the buildings at the Sylvania Campus. The scope of the seismic evaluations included ASCE Tier 1 screenings and limited Tier 2 deficiency only evaluations, as well as some recommendations for seismic retrofit work to address any deficiencies. The report associated with this work, titled Portland Community College Sylvania Campus - Seismic Evaluation Report is dated November 15, 2011; the report contains 29 pages. The CC building seismic evaluation is located on pages 13 thru 15 of that report; those pages are attached to this letter for reference. In 2013, KPFF and GBD Architects designed a seismic retrofit scheme for the CC building under the 2010 Oregon Structural Specialty Code/2009 International Building Code. This retrofit scheme addressed most of the seismic deficiencies that were noted in the 2011 report; as noted on the attached pages from the report the following deficiencies were not addressed: 1. Deterioration of concrete and corrosion of post-tensioning anchors. These items are not specifically a seismic deficiency but are a general building condition issue, and as such the location and extent of corrosion were not extensively documented in the report. As part of the re-roofing work we recommend as a minimum that any conditions where corrosion or deteriorated concrete will be covered by new roofing work be repaired prior to being covered. The type of repair required will depend on the location and extent of the areas needing repair; a structural engineer should be consulted prior to beginning any repairs that may impact structural members or connections. 111 SW Fifth Avenue, Suite 2500 Portland, OR kpff.com

3 Ms. Krista Phillips, Managing Architect Portland Community College Re: PCC Sylvania CC Building Seismic Work Clarifications January 25, 2019 Page 2 2. Diaphragm discontinuity. As part of the seismic retrofit, an analysis of the roof diaphragm was performed which showed that the discontinuity where roof stepping occurs was not a seismic deficiency with respect to the overall roof diaphragm demands. However, there are (4) 30 square pop-up roofs in the area bounded by gridlines C to F and 32 to 35 which have a seismic deficiency. These pop-ups are laterally braced by concrete walls on two of their four sides, with the other two sides being glazed. There is an existing load path to seismically brace these roofs, but it is not compliant with current force and detailing requirements. It was decided to exclude these areas from the seismic retrofit due to the relatively high cost to benefit of the retrofit work. Note that this deficiency is a localized issue that does not impact the overall seismic performance of the building. There are several possible options for retrofit of these roof areas that could be constructed with no impact to re-roofing work. The retrofit options would generally include adding shear walls or diagonal bracing to one or both of the glazed sides of each pop-up roof. Additionally, the retrofit could probably be designed to be installed without requiring the removal or replacement of the existing glazing systems. Our initial seismic evaluation was based on limited site observations and our review of the information included in the original structural drawings. It was assumed that the original structural drawings accurately depict existing conditions since it was not practical to verify member sizes and reinforcing, except in limited cases. The opinions we have presented are consistent with our best engineering judgment, but in no way warrant or guarantee the existing construction of the project, that concealed problems do not exist, or the future performance of the structural systems. If you have any questions or need further information, please call me. Sincerely, Nick Saari, SE Associate Attachment cc: Ryan Burt, GBD Architects NS:kw _PCC Sylvania CC Building Seismic Work Clarifications_

4 CC Amo DeBernardis College Center Structural Systems: Gravity: The roof is constructed of precast, pre-stressed concrete channels supported by post-tensioned cast-in-place beams and columns. At the center of the building is a raised portion of the roof which consist of twoway cast-in-place concrete slabs supported by concrete walls and beams. Portions of the ground floor over basements are constructed of cast-inplace one-way slabs supported by concrete joists, beams and columns. The building is supported by both piles and spread footing foundations. Seismic Force Resisting System: Lateral forces are resisted by long span concrete moment frames and small pieces of concrete walls. The roof diaphragm is made up of a light-weight concrete topping slab over the precast channels. The topping is doweled directly into the tops of the concrete frame beams. Condition / Comments: Some incidents of corrosion were seen at exterior post-tensioning anchorages and embedded steel plates. Cracking and water penetration is visible in the bottoms of the raised two-way roof slabs at the center of the building. ASCE 31 Evaluation Data: The building is classified as Type 8 - Concrete Moment Frames in both directions. The following checklists were evaluated as part of the ASCE Tier 1 screening: Year Constructed Area Footprint Stories Building Data ,000 s.f. 425 ft x 315 ft 1 + Penthouse & Basements Story Heights 15-8 Building Height Original Code Latitude: Longitude: max UBC Basic Structural Checklist Supplemental Structural Checklist 3.7.8S Geologic Site Hazards and Foundations Checklist 3.8 Basic Non-Structural Checklist Intermediate Non-Structural Checklist Seismic Data Pseudo Lateral Force Calculation C = 1.1 S a = 0.71 W = 27,418 k V = CS aw = 20,277 kips Seismic Evaluation Report - Appendix B PORTLAND COMMUNITY COLLEGE - SYLVANIA CAMPUS CC

5 CC Amo DeBernardis College Center (continued) The table below lists only items that were found to be seismically deficient: ASCE 31 Tier 1 Screening - Deficiencies Summary Checklists Non-Conforming Items Description* -Deterioration of Concrete -Cracking and water penetration visible in bottom of high two-way slabs at building center Structural Geologic Site Hazards and Foundations Nonstructural -Corrosion of Post-Tensioning Anchors -Shear Stress in Columns -Concrete Columns -Pre-stressed Frame Elements -Frame Shear Failures -Strong Column / Weak Beam -Column and Beam Bar Splices -Stirrup and Tie Spacing -Diaphragm Discontinuity -No Pile Cap Top Bar Reinforcing -No deficiencies confirmed -Cladding Isolation -Some exterior post-tensioning anchors have begun to corrode -Columns are overstressed in shear by 20% -A number of columns are not dowelled into the foundations and cannot resist lateral shears -Some post-tensioned beams have average prestresses exceeding the recommended values for moment frames -Some columns will fail in shear before failing in flexure -The frame members do not meet the strong column / weak beam criteria -Column and beam bar splices have inadequate lap lengths and/or laps occur within areas of plastic hinging -Beam stirrup and column tie spacing do not meet requirements for ductility -The raised portions of the roof at the center of the building create a discontinuity in the roof diaphragm -Pile caps do not have top reinforcing for resisting uplift -Cladding is not isolated from the structural frame in order to accommodate building drift * An ASCE 31 Tier 2 deficiency only evaluation may be performed to further investigate items found to be deficient. SEISMIC DEFICIENCIES MITIGATED BY BRBF RETROFIT. DEFICIENCIES NOT MITIGATED. Seismic Evaluation Report - Appendix B PORTLAND COMMUNITY COLLEGE - SYLVANIA CAMPUS CC

6 CC Amo DeBernardis College Center (continued) Recommendations: Further investigation should be made into the cause of cracking observed at the raised bay two-way roof slabs to determine whether strengthening is necessary. Corroded post-tensioning anchors should be repaired to prevent further damage. We recommend that a contractor who has experience in post tensioning repairs be hired to evaluate the extent of damage and develop a repair plan. Due to the high number of deficiencies found with the existing moment frame system and the difficulty in retrofitting the frames to meet acceptable standards, we recommend converting the building lateral system to a concrete shear wall or buckling restained braced frame building by adding new lateral elements throughout the building in both directions. The few existing walls within the building could be extended/thickened or otherwise used in conjunction with the new lateral elements to resist lateral forces. New lateral elements can be strategically located within the existing layout to minimize occupant disruption. Approximately 150 feet of 12 thick walls in each direction would be required or 6 bays of buckling restrained braced frames. Attempting to retrofit the moment frame system would require work to be performed on every beam and every column with significant expense and disruption to occupants. The diaphragm discontinuity created by the raised roof bays at the center of the building can be considered a low priority due to the localized nature of the discontinuity and the presence of concrete walls and beams that should be capable of transferring diaphragm loads down to the main roof diaphragm. The absence of top reinforcing bars in the pile caps would no longer be a concern once the building was converted to a shear wall building, except possibly at pile caps located at the ends of new lateral elements. These individual pile caps would only be retrofitted if further analysis determines that uplift resistance is required at lateral elements. Adding shear walls will stiffen the structure and reduce the expected building movements during a seismic event. Thus, cladding isolation would be much less of a concern once the building is seismically upgraded. Due to the high number and severity of the deficiencies found, and the high level of occupancy and use of the building, this retrofit should be considered highest priority. Seismic Evaluation Report - Appendix B PORTLAND COMMUNITY COLLEGE - SYLVANIA CAMPUS CC