Post on 09-May-2020
09.18.17
Ms. Melissa Brand-Vokey
Architects Design Group
4131 North Central Expressway, Suite 200
Dallas, Texas 75204
Re: Wylie Public Safety Building
Wylie, Texas
JQ Project No. 3170285
Dear Ms. Brand-Vokey:
JQ Engineering (JQ) performed a limited structural review of the Wylie Public Safety Building located at
2000 North Highway 78, Wylie, Texas on July 11, 2017. The purpose of the review was to observe and
document the general condition of the structure, note any observed deficiencies, perform a structural
analysis of typical framing elements and provide repair recommendations for noted deficiencies. The
structure was damaged by a severe hail storm the previous year and has been vacant since.
The following documents were available for review:
• Original construction documents for “Wylie Complex” produced by Speed Fab-Crete Corporation
International, dated September 23, 1986 (47 sheets);
• Report by McCarthy Architecture dated September 30, 2016 (48 pages);
Our findings are as follows:
Building Description
The Wylie Public Safety Building is a single-story building with an open courtyard in the center (Photograph
1). The structure is approximately 200 feet by 200 feet in plan. Per the original construction documents,
the perimeter and courtyard walls of the building are supported by belled piers with 12-inch wide
reinforced concrete grade beams on 8-inch deep void boxes. The interior columns are supported by
isolated belled piers. The 4-inch thick reinforced concrete slab-on-grade ground floor is on a 4-inch sand
bed with a 6-mil polyethylene moisture barrier. The slab-on-grade is reinforced with #3 bars at 18 inches
on center each way and is cast integrally with the grade beams. The exterior walls are 5-inch thick
loadbearing precast concrete wall panels with perimeter steel channels. Interior HSS 4x4x1/4 columns
support steel joist girders, which span in the north-south direction. Open web steel roof joists spaced
approximately 6’-0” on center span between the exterior walls and interior joist girders in the east-west
direction and support a 1 ½” type F, 22 gauge metal roof deck. Per the original construction documents,
the original roof system consisted of ¾” insulation board covered with a modified bitumen “BRAI” roof
membrane. This original roof has recently been covered with a modified bitumen membrane as a
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temporary solution to the hail damage. The east side of the northeast corner of the building has a canopy
that is assumed to have similar construction to the main structure.
Observations
In general, the structure was observed to be in fair condition. No control joints were observed in the
concrete slab-on-grade and thus the slab has cracked at various locations throughout the building,
especially parallel to the courtyard walls (approximately 2 feet inboard from the courtyard wall), diagonal
cracks from the reentrant corner of the courtyard towards the perimeter of the building and in the
southwest corner near the restrooms (Photographs 2, 3 and 4). The length of most of these cracks
spanned multiple rooms, extending beyond the partition walls. Absent the typical isolation joints around
the columns, cracks were also observed around the bases of the columns in a few locations (Photograph
5). Staining was observed on the floor of Rooms 126 and 127, located on the East side of the building
(Photograph 6). This staining appears to be the result of leaks in the existing roof running down the joists
and dripping down onto the floor below.
Cracks exhibiting efflorescence were observed on the blue-painted top portions of the exterior precast
concrete tilt-wall panels. At a few locations, this cracking was also visible on the interior face of the
concrete walls (Photographs 7 and 8). Deteriorated joint sealant was observed at the vertical joints of
these panels at several locations (Photograph 9). Failed joint sealant also observed at the interface
between the perimeter grade beam and the concrete sidewalk (Photograph 10). Delaminations were
observed at a few locations on the precast panels, with the most severely delaminated location being a
24”x 3” section adjacent to a joint on the North elevation of the building (Photograph 11). Additional
delaminated sections and corroded channels at the panel perimeter were observed at the North and East
elevation entrances, in addition to a delaminated section adjacent to a spall at the East doorway of the
central courtyard (Photograph 12). Corrosion was observed on an exposed drip cap at the corner of a
soffit section at the North elevation entrance (Photograph 13). Further corrosion was observed on the
door frames and drip caps at a few locations (Photograph 14). Staining was observed throughout the
exterior walls with one location at the East elevation exhibiting what appeared to be mold growth likely
caused by moisture (Photograph 15).
Non-loadbearing light gauge metal studs, located beneath the window sills and on the interior face of the
precast concrete walls, were observed to be bent at a few locations (Photograph 16). These slight
deformations appear to have occurred when the drywall and insulation was removed from the walls. The
metal studs also appeared to be partially corroded at a few locations. The metal stud framing is not part
of the structural framing of the building.
Cracking was observed at several locations of the interior non-load bearing partition walls. Several of
these cracks originated from the top corners of the door frames (Photograph 17). A large, vertical crack
was observed at the wall of the women’s restroom (Photograph 18).
Both the open web steel joists and joist girders were observed to have minor corrosion at many locations
(Photographs 19, 20 and 21). Similarly, the cap plates of the HSS columns were observed to have minor
corrosion (Photograph 22). Deformations were observed on the underside of the ribbed metal deck.
Additionally, the underside of the metal deck was observed to be severely corroded in a few locations
(Photographs 23 and 24).
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Ponding water was observed over the modified bitumen roof membrane along the east and west parapet
walls (Photograph 25). Although no ponding water was observed on the drive-through canopy roof,
staining was prevalent on the underside of the canopy (Photograph 26). The scuppers located at the
perimeter of the roof appeared to be clogged with debris at most locations (Photograph 27). Similar to
the sealant failure observed on the tilt-wall panels, gaps were observed in the joint sealant at the parapet
walls that form the protruding saw-tooth section of the roof (Photograph 28).
Analysis
Two typical interior open web steel joists, one typical interior joist girder and one typical interior column
were analyzed to determine allowable live loads. The structural elements were analyzed based upon the
2015 International Building Code for self-weight, superimposed dead load and live load. The following
dead load assumptions were made during analysis: 1 ½” Type F 22 gauge metal roof deck, ¾” rigid
insulation board, single-ply 80 mil Fibertite modified bitumen roof and 10 pounds per square foot (PSF)
for supported ceiling and mechanical systems.
The two typical interior open web steel joists were analyzed based on information contained in the
original construction documents and data gathered at the site. These included the following: Vulcraft
20K4 joist spanning approximately 33 feet and spaced approximately 6 feet on center, and a Vulcraft 28K9
joist spanning approximately 48 feet and spaced approximately 6 feet on center. The typical interior joist
girder analyzed was a Vulcraft 32G 6N 7.2K joist girder spanning 36’-3 ½”. The typical interior column
analyzed was an HSS 4x4x¼, 13’ – 4 ½” tall.
Based on analysis of these structural elements, the existing structure has a maximum allowable live load
of 22 PSF. The 20K4 open web metal joist controlled the allowable live load. Per current code, the typical
required design live load for roofs is 20 PSF, so this result aligns with current design requirements. In
addition, review of the original construction documents noted that the total design load for the structure
was 40 PSF which is typically an acceptable total design load for structures of this type. Atypical loading
such as roof top mechanical units may require isolated reinforcing of the roof structure.
Discussion
Slab-on-Grade Cracking and Movement
Clay soils, common in north Texas, are “active” soils, in that they swell when wet and shrink when dry.
Swelling and shrinking of the subgrade material can result in heaving (upward movement) or subsidence
(downward movement) of the building foundation and sidewalks. Trees around the perimeter also can
cause desiccation of the soils, which results in subsidence of the slab. It is important to maintain a
constant moisture content in the soils around and under these buildings to help minimize the potential
for movement imparted by the shrink/swell cycling.
Slab-on-grade construction typically specifies control joints in the slab; however, no control joints were
installed in the existing slab. In addition, there are no blockouts in the slab around the piers or supported
columns. As the subgrade moves, the slab cracks at random locations rather than on the grid pattern
induced by control joints. These factors have resulted in random cracking in the slab throughout the
structure.
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Most of the cracks observed in the drywall were minor; however, the wide crack in the women’s restroom
appears to be the result of the slab-on-grade heaving as the subgrade swells, possibly caused by a leak in
the plumbing drain lines. Video inspection of the drain lines may be able to identify the location of any
breaches in the lines.
Roof Deck and Membrane
Due to the continuing leaks in the roof, even after the temporary modified bitumen membrane was
installed, it is likely that water has become trapped between the top side of the metal roof deck and the
existing roof membrane system. When the top side of the metal roof deck is uncovered, it should be
inspected for any additional deterioration. It is likely that additional corrosion will be discovered, which
will require additional repairs.
Concrete Wall Panel Modifications
As part of the planned renovation, it is possible that alterations of the existing concrete wall panels to
create additional openings or to enlarge the building into the existing courtyard. Such structural
modifications are normally possible, but typically require the installation of supplemental reinforcing of
the existing concrete wall panels. Further, openings are best be contained within a single wall panel so as
to not require the installation of supplemental columns and associated foundations. As the building
renovation is planned, further review of the existing building will be required so as to fully develop the
required structural modifications.
Recommendations
The following repairs should be completed as part of the building renovation:
1. Rout and seal cracks in slab-on-grade.
2. Remove and replace unsound concrete at exterior precast panels.
3. Clean and coat corroded open web steel joists, joist girders, metal deck, miscellaneous steel, and
exterior doors, frames and drip caps.
4. Remove existing roof membrane and protection board to expose top side of metal deck and
inspect for deterioration of the metal deck.
5. Remove and replace areas of metal roof deck where corrosion was observed from below or where
significant deterioration is discovered during inspection of the top side of the metal deck.
6. Remove and replace deteriorated joint sealants.
7. Video inspect drain lines in the women’s restroom if this restroom and associated underfloor
plumbing is to remain.
8. Remove debris from existing roof scuppers.
9. Trim tree limbs that are overhanging the roof to avoid additional debris collecting in the roof
scuppers.
Our recommendations do not address non-structural items such as interior partitions as we have assumed
that essentially all existing interior finishes will be demolished as part of the renovation. Further, these
recommendations to not address structural modifications related to building renovation or expansion as
the scope of such changes is unknown at this time.
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Disclaimer
The opinions and comments provided in this report are based upon field observations as part of our scope
of services. JQ has ascertained to the best of our ability the visually apparent defects in the building
structure and envelope. However, as field observations were conducted on structures in which the
majority of the building envelope elements are concealed, JQ cannot be responsible for failing to ascertain
deficiencies which were not visible due to the existing conditions in the building. No warranty, expressed
or implied, regarding the condition of the building is intended. In addition, no representation as to the
expected useful life of the building or other components identified in this report is made.
If you have any questions or if we can be of further assistance, please contact us.
Sincerely yours,
JQ Engineering, LLP
Texas Registered Engineering Firm: F-1294
Stephen H. Lucy, P.E. Julie Bolding, P.E.
Partner Senior Project Engineer
Enclosures
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Photograph 1 - Overall view of the South elevation
Photograph 2 - Crack in slab parallel to courtyard wall
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Photograph 3- Cracking at concrete slab-on-grade from reentrant corner of courtyard
Photograph 4 - Close-up of cracking at concrete slab-on-grade
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Photograph 5 - Cracks around base of column (overlaid in red for clarity)
Photograph 6 - Staining on concrete slab-on-grade due to leaking roof
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Photograph 7 - Efflorescence on cracking at top portion of precast concrete panels
Photograph 8 - Cracking on precast concrete wall interior
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Photograph 9 - Deteriorated joint sealant
Photograph 10 - Failed joint sealant between perimeter grade beam and sidewalk
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Photograph 11 - Delaminated concrete at precast concrete panel
Photograph 12 - Corrosion on channel at perimeter of precast panel with delaminated concrete and
deteriorated coating
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Photograph 13 - Corrosion on metal drip cap at edge of soffit
Photograph 14 - Corrosion at door frame and metal drip cap
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Photograph 15 - Mold growth on precast concrete panel
Photograph 16 - Bent light gauge metal studs
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Photograph 17 - Cracking at partition wall above door frame
Photograph 18 - Wide opening in wall of women’s restroom
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Photograph 19 - Corrosion on joist girder
Photograph 20 - Corrosion on open web metal joist
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Photograph 21 - Close-up of corrosion on joist girder
Photograph 22 - Corrosion on HSS column and cap plate
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Photograph 23 - Deformation on underside of metal roof deck
Photograph 24 - Corrosion on underside of metal roof deck
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Photograph 25 - Ponding water on roof
Photograph 26 - Staining on underside of canopy ceiling tiles
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Photograph 27 - Debris in scupper
Photograph 28 - Joint sealant failure at precast concrete panel parapet