|Seismic Hazard Rating
|Number of Stories
||451 Jersey Street
|Gross Sq. Ft.:
The well proportioned building has a "T" shaped floor plan with the top of the "T" defining the north wing and a stem defining the south wing. The partial basement is located under the front half of the north wing. There is an ornate ceiling in the main reading room. An unimproved attic is present above the ceiling, formed by a space between top and bottom roof truss chords.
The south wing roof could collapse during a major seismic event due to a potential failure of the non-reinforced supporting masonry walls. The building's general lack of lateral force capacity coupled with the complete lack of connections between the roof diaphragm and the resisting walls support the above seismic hazard rating. A seismic retrofit is required to mitigate the substantial risk to life safety would involve strengthening existing walls and adding new "braced" walls.
New walls will be located along the perimeter of both wings and extend from new foundations to the underside of roof trusses.
The main level of this library is about one flight of stairs above the sidewalk grade, making the building inaccessible to wheelchair users. Work areas, service counters, and restrooms are not accessible. Doors are too narrow, and there is no elevator. The remodeled area and path of travel to that area must be accessible to the disabled.
Building code impacts involve updating the building to comply with current life safety requirements such as exiting, heating, ventilation, plumbing, electrical, lighting and other control systems. Attention will be placed on preserving the historic fabric of the existing building. The removal of asbestos containing materials will require relocation of building occupants. Lead that is impacted by construction will be abated.
Improvements include a small expansion to compensate for the loss of existing area due to seismic and accessibility improvements. The proposed expansion will be limited to the rear of the building. The renovation work will involve upgrading utilities, electrical service, and lighting. Other work includes new floor finishes, additional data/electrical outlets, improved staff areas, increased storage space, and a refurbished meeting room.
- The non-reinforced masonry walls do not have adequate in-plane shear capacity to resist lateral loads in both the North and South wings.
- The non-reinforced masonry walls exceed allowable h/t limits in both the North and South Wings.
- The anchorage between the roof diaphragms and the walls cannot transfer out-of-plane loads from the walls to the roof diaphragms nor can the connections between the roof diaphragms to the walls.
- The roof and first floor diaphragms lack sufficient shear strength.
- The first floor diaphragm lacks reinforcing around the main stair opening and at the re-entrant corners between the two wings.
- The chord members at the first floor are inadequate. At the South Wing chord members can not develop the required tensile forces. At the North Wing the connections between the steel beams actions acting as chord members cannot transfer tensile forces between the beams.
- The connections between beams acting as collectors can not transfer tensile loads between the beams. Additionally, there is no positive means of transferring collector loads into the resisting walls.
- Soil bearing pressures along wall line B due to earthquake and dead loads greatly exceed allowable values.
- The non-reinforced masonry chimney extends above roof more than twice the least dimension of the chimney. The enclosing the main entry stairway are made of hollow clay tile.
- There are loose roof tiles over west side entrance.
- The non-reinforced brick parapet height to thickness (h/t) ratio exceeds allowable limits.
- Shotcrete shear wall elements, 8" thick, form the basis of a new lateral force resisting system. New walls are located along each of the perimeter walls in wings and extend from new foundations to the underside of the roof trusses. Shotcrete walls are selected to resist lateral loads as they are;
- Stiff, thereby "attracting" load and insuring reduced loads to the masonry walls.
- Readily constructed and commonly used in existing structures.
- Double angles at the level of the trusses bottom chords form a horizontal truss to carry loads to the shotcrete walls. This relieves the wooden roof diaphragm from carrying any more load than is own inertial load. Both wings have this horizontal truss.
- A continuous 6x6 angle, (8x8 at lines 2 and 4), at the perimeter of the building, epoxied into the masonry wall even with the truss bottom chords, collects loads and acts as a chord to the horizontal truss. The angle acts to grip and tie the top of the wall together as well, reducing the possibility for out of plane failure at the top of the wall.
- W8x58 strong-backs extend from new foundations to the bottom of the trusses and brace those walls without shotcrete against out-of-plane loads. These strongbacks coupled with the continuous angle at the top of the wall serve as a backup vertical system to carry the trusses at the South wing.
- Single angles bolt to the underside of the first floor slab and continue into shotcrete walls to;
- Act as diaphragm chords and collectors.
- Provide collectors and reinforcing at reentrant corners.
- Removing hollow clay tile walls on either side of the entry stairway and replacing them with metal stud walls.
- Securing loose mission tiles above the West entrance.
- Cut short and anchor existing brick chimney above roof.
- The two floors of the existing building are not accessible to people with disabilities.
- Staff work areas and service counters are not accessible.
- Restrooms are not accessible.
- Doors are too narrow or do not have accessible hardware.
- Provide and install new ramp to access lower floor from street level and install new elevator.
- Install new accessible service counters.
- Renovate existing restrooms to make them accessible. Install new toilet fixtures as required.
- Widen existing door openings and install new doors and hardware to comply with ADA requirements.
- The boiler was replaced two decades ago and may need to be upgraded.
- Air ventilation is very poor, and dependent upon a radiant heating system.
- The building is in need of a new water heater and water pipe distribution system.
- Refurbish or replace the boiler and reconnect to existing radiators, as well as new radiators serving the rear of the building.
- Consider installing a forced air ventilation system.
- Install new water heater and water pipes.
- Replace existing ducts and piping as required.
- The main electrical panel is not adequate to serve library electrical power needs.
- In general, light fixtures are inefficient and do not relate to the historic character of the building.
- There are not enough electrical power outlets.
- Need to relocate and upgrade existing telephone panel.
- Install new electrical main panel with enough capacity to handle the required load.
- Replace all existing light fixtures with new energy-saving fixtures and historically appropriate fixtures.
- Inspect and upgrade wiring and conduits as required.
- Install additional data/communication outlets.
- Install new telephone / telecommunication panel.
- Install new underground transformer vault in front of the building.
- The building lacks a central fire alarm and smoke detection system.
- There are not enough emergency exit signs.
- Emergency lighting needs to be added.
- The building needs security grilles.
- Additional fire extinguishers need to be added throughout the building.
- There is no book security sensor.
- The building lacks adequate indoor/outdoor security lights.
- Security window and door grilles need to be replaced.
- Install new smoke detectors and fire alarm system.
- Install new exit signs and emergency lights.
- Install new security grilles.
- Install new fire extinguishers at strategic locations in the building.
- Install new book security sensor.
- Install new interior and exterior security lights.
- Install new security grilles consistent with the building’s historic character.
- Asbestos Containing Materials (ACM’s) are identified throughout the building.
- Abate asbestos if found in the vinyl floor tiles and mastics, heating hot water pipe and fitting insulation, and transite flue from boiler.
- Where impacted by construction, abate asbestos in built up roof, counterweight ropes on double hung wood windows, ceramic tile grout and mastic, transite panels, window/door caulk and window putty, and fibered roof patch.
- Lead that is impacted by construction shall also be abated.
- The seismic retrofit and disabled access work will result in the loss or displacement of valuable public space, and there is no room to expand staff workroom and storage areas.
- The increased use of computers and Internet communications will require new flexible conduit runs and new data line distribution systems.
- The meeting room lacks any audio/visual equipment.
- Improvements will include a small expansion at the rear of the building to compensate for loss of space.
- Add data/communication distribution panel and distribute conduits where needed.
- Upgrade the existing meeting room with audio/visual equipment.
- There are at least two overgrown trees in front of the building.
- The community garden is located back of building and maintained by the community.
RECOMMENDED CORRECTIVE MEASURES
- Trim overgrown trees and plantings around the building.
- Develop a landscape protection, restoration, and maintenance plan.
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