55 Laguna Street Draft EA
Total Page:16
File Type:pdf, Size:1020Kb
CONSULTING STRUCTURA REPORT L ENGINEERS RICHARDSON & WOODS HALLS SEISMIC REVIEW PREPARED FOR MERCY HOUSING & A.F. EVANS San Francisco Telephone 415 693 1600 Facsimile 415 693 1760 Internet Address www.holmesculley.com 130 Sutter Street Suite 400 Date: June14, 2004 Project No: 04033.10 San Francisco Prepared by: Reviewed by: CA 94104 USA Offices in John Hare, P.E. Denny Kwan, P.E. New Zealand PRESIDENT SENIOR ENGINEER Australia PAGE i Executive Summary Holmes Culley has completed a phase 1 seismic review of 4 buildings at the UC Extension Laguna Site, for the purposes of a possible lease to Mercy Housing and A.F. Evans for housing purposes. The buildings are: · Woods Hall · Woods Hall Annex · Richardson Hall (in two parts – the main building and the annex) · Middle Hall Gymnasium The buildings are all of a similar age, having been designed and constructed during the 20’s and 30’s. They are generally of one or two stories in height, and most with partial basements. The construction of each is similar. Typically they have clay tile roofs, supported on wood sheathing and steel or wood trusses. The main structure below roof level is reinforced concrete, either load-bearing walls or frames. The foundations are typically either concrete pads or strip footings, for columns and walls respectively. The buildings are generally in good condition, and well maintained, although there is some cracking in the north side of Woods Hall, and some water damage, in particular in the basement of the Middle Hall. Seismically, the roof structures of all of the buildings are deficient, due to the lack of strength of the sheathing and its connection to the supporting structure. This may be mitigated generally either through steel cross-bracing or the installation of a plywood ceiling diaphragm. Richardson Hall has severe deficiencies in the discontinuity of the concrete shear walls below the north floor, in both the north wing of the main building, and the entire annex building. There is also a horizontal offset of the north wall of the west wing, above the second floor. These are potential life safety and collapse hazards. There are also some non-structural hazards comprising mainly the hollow clay tile partitions (which should be removed, encapsulated, or strengthened; and possibly the chimney of Richardson Hall, which requires further assessment. Mitigation measures have been proposed for all of the conditions above, and broad cost estimates have been developed, based on an earlier report prepared for Richardson Hall, by Degenkolb. These cost estimates are presented below, excluding any allowance for architectural upgrades that may be triggered by this work. These cost estimates are for preliminary budgeting purposes only, and should not be construed as a final estimate of the overall cost of strengthening. They exclude any allowance Richardson & Woods Halls Seismic Review File:H:\#HC_SFO.STR\2004\04033.10\WP\04033.10RT_FINAL.DOC Project No: 04033.10 Date: Tuesday, 15 June 2004 PAGE ii for soft costs. It should be noted also that this assumes that the main structures of each building are compatible with any envisaged uses. If significant alterations are required to the structure to incorporate new uses, there may be significant cost penalty. In particular, it is apparent that both Woods Hall and Richardson hall have internal shear walls that are likely to conflict with future planning requirements. Partial or total removal of these walls will add significant cost penalty to the project. These costs are generally in line for what might be expected for similar levels of seismic upgrade for buildings in the San Francisco area, with the exception of the Richardson Hall Annex, which is distorted by the amount of work required at both foundation and roof level, for a single story building. It is recommended that further study is completed to develop a more comprehensive preliminary design for cost estimating purposes. Table 1 : Preliminary Cost Estimates Building Overall cost Unit Rate cost $,000 $ per sq. ft. Woods Hall $1,401 $55 Woods Hall Annex $516 $48 Richardson Hall $2,234 $64 Richardson Hall Annex $790 $235 Middle Hall Gymnasium $737 $60 Sub-Total $5,679 Overhead and Profit, 10% $568 Contingency, 15% 852 Total $7,098 Richardson & Woods Halls Seismic Review File:H:\#HC_SFO.STR\2004\04033.10\WP\04033.10RT_FINAL.DOC Project No: 04033.10 Date: Tuesday, 15 June 2004 PAGE iii CONTENTS Executive Summary............................................................................................................i 1. Introduction ............................................................................................................... 1 2. Scope of Work ........................................................................................................... 2 3. Limitations.................................................................................................................. 2 4. Statutory Requirements............................................................................................... 2 5. Earthquake Loads ...................................................................................................... 3 6. Documents Reviewed ................................................................................................. 3 7. Building Evaluations................................................................................................... 3 7.1. General ............................................................................................................ 4 7.1.1. Site Geology and Soils..................................................................................................................4 7.1.2. Building Types ................................................................................................................................4 7.2. Woods Hall....................................................................................................... 4 7.2.1. Existing Structure...........................................................................................................................4 7.2.2. Seismic Assessment .......................................................................................................................4 7.2.3. Recommendations .........................................................................................................................4 7.3. Woods Hall Annex ............................................................................................ 4 7.3.1. Existing Structure...........................................................................................................................4 7.3.2. Seismic Assessment .......................................................................................................................4 7.3.3. Recommendations .........................................................................................................................4 7.4. Richardson Hall ................................................................................................ 4 7.4.1. Existing Structure...........................................................................................................................4 Richardson & Woods Halls Seismic Review File:H:\#HC_SFO.STR\2004\04033.10\WP\04033.10RT_FINAL.DOC Project No: 04033.10 Date: Tuesday, 15 June 2004 PAGE iv 7.4.2. Seismic Assessment .......................................................................................................................4 7.4.3. Recommendations .........................................................................................................................4 7.5. Richardson Hall Annex ...................................................................................... 4 7.5.1. Existing Structure...........................................................................................................................4 7.5.2. Seismic Assessment .......................................................................................................................4 7.5.3. Recommendations .........................................................................................................................4 7.6. Middle Hall Gymnasium ................................................................................... 4 7.6.1. Existing Structure...........................................................................................................................4 7.6.2. Seismic Assessment .......................................................................................................................4 7.6.3. Recommendations .........................................................................................................................4 8. Conclusions............................................................................................................... 4 9. Cost Estimates............................................................................................................ 4 Appendix A – Detailed Cost Estimates..............................................................................22 Richardson & Woods Halls Seismic Review File:H:\#HC_SFO.STR\2004\04033.10\WP\04033.10RT_FINAL.DOC Project No: 04033.10 Date: Tuesday, 15 June 2004 PAGE 1 1 . Introduction Holmes Culley has been engaged to perform a structural review of the existing Richardson and Woods Hall buildings (including the Woods Hall Annex and the Gymnasium) at the UC Berkeley Extension Campus site, bounded by Herman, Laguna,