S02 - Draft Structural Report dtd 6-15-2016.pdf

June 15, 2016

Brent R. Sutter, P.E.

Sr. Project Manager/Principal

Woodward & Curran, Inc.

980 Washington St, Suite 325

Dedham, MA 02026

RE: VA BUILDING 3 PATIENT PARKING GARAGE JAMAICA PLAIN, MA

WO 3835

Dear Brent, Thank you for the opportunity to serve as your structural engineering consultant on this project. At the request of Woodward and Curran, Inc. we have visited the VA Campus in Jamaica Plain, MA to evaluate the extent of the failed shear connections and other life safety issues that we noted in the patient parking garage during our last visit on June 1, 2016. We initially noted these concerns during our review of the adjacent garage in 2014.

When walking through the patient garage to review repairs and alterations at the connection between the two garages in 2014 we noticed that several of the double tee (DT) floor members were rocking as vehicles drove over. When vehicles cross over the DT joints, noticeable vertical displacement and movement of the DT occurs due to failed connections. We brought this to the attention of the VA

Maintenance Staff and understood that another engineering firm was working on the restoration of this garage. When we returned in June of this year to update our drawings for the adjacent garage we noted that this issue had not been addressed and we brought this to the attention of the VA Maintenance Staff.

The VA Building 3 Patient Parking Garage has 3 levels and was designed in 1996 by Payette Associates

(Architect) and Simpson, Gumpertz & Heger (SGH) (Structural Engineer). The garage is constructed primarily of precast concrete, the structure consists of double tee decks supported by precast concrete spandrels, beams, litewalls, shearwalls and columns that were manufactured in a plant, transported to the site and erected. To facilitate our review, the VA provided BSE with the original construction drawings and a Condition Appraisal Report by Simpson, Gumpertz & Heger (SGH) dated April 9, 2013. This report is a comprehensive opinion of the necessary repairs to the garage and our scope is not to recreate this report but to provide an opinion as to the importance of the proposed repairs and items that appear to have developed or worsened since this report was completed.

A site visit was made by BSE on June 1, 2016 to review the existing conditions and to remove sealant from the DT joints to inspect the existing connections. The DT flange connections (see figure 1) are spaced regularly along the joints between DTs and serve multiple purposes in the design and function of a precast

DRAFT

DRAFT -VA Building 3 Parking Garage

Precast Double Tee Connection Investigation parking garage. They transfer vertical wheel loads across the joints between the DTs and are a major contributor to the ability of the individual DTs to work together as a singular diaphragm. The diaphragm collects and distributes lateral loads (wind and seismic) to the lateral force resisting elements (shear walls). A failure of these connections will create excessive movement in the deck due to the vehicle loads and more significantly it can alter the design load path of the lateral loads and significantly alter the buildings performance in a high wind or seismic event.

The DT shear connections consist of stainless steel embedded plates cast into the flange of the DT (See

Figure 1). To create a shear connection between the

DTs, a 4-inch stainless steel round or rectangular

“erection” bar (bar width is a function of joint width) was field welded to each stainless steel embedded plate.

Figure 1

We identified five joints where visible vertical displacement of the DT was observed after our test vehicle traveled across the DT joint. The vertical displacement of the precast DT indicates that all or most of the

DT shear connections have failed This generally results from an initial single connection failure (due to poor welding or excessive loading) which overstresses the adjacent connections which then fail and continue the process across the length of the joint.

Eight test cuts were taken through the joint sealant at multiple locations in both failed and functioning joints to inspect the existing connections. At each test cut where vertical displacement was observed the shear connections had failed. At one location BSE was able to remove the shear connection bar

(jumper plate) from the joint, see Photo 2. Note the irregular and wandering failure points of the welds

(See Photos 1 and 2) indicating an inconsistent weld and shear failure. The test cuts taken where there was no visible displacement, each shear connection was intact. At one joint at level 2 there is a missing

Photo 1 – Failed shear connection.

Photo 2 – Removed shear connection bar.

bearing pad which appears to have caused the DT to drop slightly. This may have contributed to the failure or been the result of the failure of the flange connections.

At the east end of the roof deck the joint between DT and CIP concrete topping over the inverted tee beam (IT) has deteriorated significantly allowing a large joint to form (See

Photo 3). The open joint allows water to leak to the level below and due to the large and irregular size of the joint is now a potential tripping hazard. The CIP concrete topping should be removed and replaced down to the top of the precast IT beam. A traffic membrane over the IT beams should be considered to minimize future delaminations.

Cast-in-place concrete (CIP) is located at the crossover lanes above the IT beams, at the transition from the parking deck to the stair towers and the deck drains. At the east end of the roof deck there is deteriorated concrete at the stair entrance (See Photo 4) and over the IT beam (See Photo 5). In addition, there are several CIP locations at the drains throughout the garage. These areas are potential tripping hazards and have significantly reduced the protection of the structural members below and should be repaired.

Photo 4 – CIP Deterioration at Stair Entrance

Precast litewalls extend down the center of the garage along column line B. Openings between the litewall panels are protected by welded steel fencing. There is a gap (greater than 4 inches) between the top of the DT flange and bottom of the fence. In most case there is a steel plate that fills this gap. The plate is missing at several locations on the roof deck, likely due to snow removal. The plate should be re-installed at all locations to ensure code compliance.

Several failed DT to litewall connections were observed at the roof deck. The connection plate protrudes above the DT deck and joint sealant and is exposed to the elements. Since the connection cannot be easily

Photo 3 – Gap at IT/DT Joint

Photo 5 – CIP Deterioration at IT

Photo 7 – Stair Landing Deterioration sealed, moisture and chlorides have worked their way into the connection and caused it to corrode and spall the surrounding concrete. At one location the embedded plate was loose and was easily removed by hand (See Photo 6). Similar to the DT flange connections these connections are critical to the lateral stability of the structure and should be exposed inspected and repaired as required.

The stair in the east tower is constructed using concrete filled steel pan system supported by steel channels attached to the precast wall panels. A portion of the stair system is suspended from the CIP beam in the ceiling. At the third level landing (exiting onto to the roof deck) there is cracking in the concrete and significant deterioration of the landing (See Photo 7) and several stair pans. There is a large crack at the edge of the landing going down the stairs which presents a potential tripping hazard (See

Photo 8).

It is our opinion that the items we have listed in this letter should be addressed as soon as possible. The failed connections represent a potential reduction in the lateral load capacity of the structure which may result in additional structural damage in the event of the high wind or seismic event. The deteriorated concrete on the parking deck, the large unfilled joints, and the damage to the stairs represent a potential safety risk to the garage users and if not repaired could lead to more significant structural damage.

Based on our observations and the list of repair items recommended in the 2013 SGH report we have prepared the following list of repair priorities for your consideration.

High Priority Repairs: We recommend that these items be addressed in the immediate future to address life safety issues and structural issues.

� Repair failed DT to DT shear connections. Cut out and replace joint sealant.

� Repair failed DT to litewall connections. Cut out and replace joint sealant

� Replace level 3 CIP concrete topping over IT beam (east end).

� Reinstall dislodged and missing DT bearing pads.

Photo 6 – DT to Litewall Connection

Photo 8 – Crack at Stair Landing

� Replace CIP concrete topping in front of east stair tower.

� Repair east stairs third level landing, steel supports and treads.

� Address the poor condition of the existing fire alarm system as noted in the SGH report.

� Install missing DT to shearwall connections per SGH report.

� Perform a biannual sweep and wash down of the parking decks. Clean drain bodies and flush drain leaders.

Moderate Priority Repairs: These items are important durability issues including preventing further water and chloride infiltration. We recommend that they be addressed in a reasonable time frame, but less urgent in nature than the items listed above:

� Sound out and replace delaminated CIP concrete toppings not addressed above.

� Cut out and replace all joint sealants and inspect for failed precast connections.

� Rout and seal precast deck, shear/lite wall and spandrel cracks.

� Repair litewall & corbel spalls.

� Remove traffic membrane systems and apply corrosion inhibiting sealer.

� Replace deteriorated plumbing and connections as noted in the SGH report, and repair concrete around drains.

� Repair/replace electrical components as noted in the SGH report.

Low Priority Repairs: These items are either cosmetic in nature or not critical to the garage structure.

Nonetheless, they are important for overall maintenance reasons:

� Seal precast lifting pockets.

� Paint steel elements (bollards, litewall railings, snow gate).

� ASR mitigation as noted in the SGH report.

� Clean the façade and cut out/replace façade sealant joints.

� Restripe all deck markings.

We trust that this report addressed your initial concerns regarding the DT shear connections. We are available to meet with you and the VA and discuss our findings upon your request. As noted above it is our opinion that repairs of the failed connections and other life safety issues be completed as soon as possible. If requested we are prepared to continue working with Woodward and Curran, Inc. and the VA to prepare repair documents. Please note that the construction season for this work is limited by temperatures and should be completed before the temperatures dip below 40 degrees F on a regular basis.

Sincerely, Becker Structural Engineers, Inc.

Josh Martin-McNaughton, PE Todd M. Neal, PE

Project Engineer III Vice President

Attachments: VA Building 3 Parking Garage Plans (Plans 10-S2 & 10-S3)

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BEARING PAD REPAIR BELOW

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CIP TOPPING DETERIORATION

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FAILED DT CONNXS

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DETERIORATED ANGLE SUPPORT BELOW

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EAST STAIR TOWER

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WEST STAIR TOWER

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BEARING PAD REPAIR BELOW

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BROKEN DRAIN LINES

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CIP TOPPING DETERIORATION

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FAILED DT CONNXS

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DETERIORATED CIP LANDING AND PANS

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FAILED DT TO LW CONNX

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FAILED DT TO LW CONNX

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