EMERGENCY MASONRY REPAIRS TO SAM H.

EMERGENCY MASONRY REPAIRSTO SAM H. WHITLEY HALLTEXAS A&M UNIVERSITY AT COMMERCEBY MARK LeMAYSam H. Whitley Hall, located on the south endof the Texas A&M University campus in Commerce, TX, is one of the tallest buildings in ruralHunt County. Constructed in 1969, the Whitley Halldormitory building is a 12-story, concrete-framedstructure with brick veneer exterior cladding. Oneach floor, the dormitory rooms are arranged alongan east-west double-loaded corridor. The concretecolumns and beams articulate the north and southfaçades, infilled with windows atop brick veneerthat is backed by concrete masonry unit knee walls.Emergency egress stairways are situated on the eastand west ends of the building. Cast-in-place reinforced concrete shear walls serve as the back-up forthe brick veneer on the east and west elevations.Portions of the brick veneer are laid in a stackedbond configuration, while other parts are arrangedin a standard running bond pattern.Beginning with a call to the engineer the morningfollowing the catastrophic event, plans were immediately discussed and implemented to cordon offthe area of the parking lot where debris had landed,provide protective coverings over entrances for thearriving students, and to assess the structural condition of the building. University personnel providedcopies of the original construction drawings, confirming that the detached masonry was an exteriorveneer system, non-load-bearing, and not integralto the structural frame of the building. The engineerimmediately replied to the university with a letterconfirming this information, with assurances thatthe building remained suitable for occupancy provided that adequate barricades were in place andoverhead protection was in place for buildingoccupants at each set of entry/exit doors.SEVERE WEATHER EVENT PROMPTSNEED FOR EMERGENCY REPAIRSWithin hours of notification by the university,the engineer’s initial observations of the failed section from the adjacent roof provided several significant clues regarding the failure:1. Dovetail anchor slots were cast into the reinforced concrete backup wall.2. Asphaltic damp-proofing was applied over theconcrete backup wall.3. Moderately to severely corroded corrugatedmetal wall ties occurred in some random portionsof the failed sections of brick (Fig. 3).4. Locations where the metal wall ties had beenpulled out of the dovetail anchor slots wereIn January 2012, 2 days prior to the start of thespring semester, an unusually severe wind stormresulted in a potentially life-threatening situation atWhitley Hall. Winds in excess of 60 mph (97 kph)caused a 10 x 12 ft (3 x 3.7 m) section of brickveneer to become dislodged from the southeast faceof the Penthouse level (Fig.1), falling 140 ft (43 m)onto the adjacent parking lot and first-floor roof ofthe resident assistant’s apartment below (Fig. 2).Fortunately, no injuries resulted from this unexpected failure.Fig. 112CONCRETE REPAIR BULLETININITIAL INSPECTION AND EVALUATIONFig. 2JANUARY/FEBRUARY 2014WWW.ICRI.ORG

No wall tiesFig. 3observed only in the lower portions of the failedsection—no such locations were observed in theupper two-thirds of the detached section of brick(Fig. 4).Preliminary findings pointed to the absence ofcorrugated metal wall ties in the upper portion ofthe failed section of brick. Despite having remainedin place for 43 years, the unique wind conditionsthat January evening most likely produced a vacuumeffect that essentially sucked the untied brick veneeroff the face of the building. The degree of corrosionobserved on the metal wall ties also created a significant degree of uncertainty regarding the integrityof the remaining ties. Immediate plans were madeto review original drawings and further investigatethe condition of the metal ties in other sections ofthe exterior walls.An examination of the original drawingsrevealed the following:1. Corrugated metal wall ties were to be spaced at16 in. (406 mm) on center horizontally andvertically.2. Damp-proofing was specified for exterior surfaces of the backup walls.3. Steel relief angles at 4 x 3.5 x 0.187 in. (102 x89 x 5 mm) were to be located at each floor levelto support the brick veneer and were to be coatedwith “mastic.”4. Weep holes were to be spaced at 24 in. (610 mm)on center, but only at the base of the masonrywalls, not at each relief angle location.Based on initial observations and a review oforiginal drawings, the as-built construction of thebrick veneer was not in compliance with the construction documents, and was a contributing factorin the failure of the dislodged section of brick.Furthermore, the lack of conformance with theconstruction documents had caused prematureWWW.ICRI.ORGFig. 4Fig. 5deterioration of the brick support and anchoragesystems that resulted in a reduced life expectancyof the brick veneer system.FURTHER INVESTIGATION ANDCLOSE-UP INSPECTIONImmediately following the initial evaluationperformed the day following the event, the university recognized the severity of the situation and tookswift and decisive measures to authorize emergencyaction. A contractor was hired and a swing stagescaffold was put into place at the location of thedislodged section (Fig. 5).JANUARY/FEBRUARY 2014CONCRETE REPAIR BULLETIN13

The remaining brick veneer was removed fromthe failed section and close-up inspections commenced. The existing corrugated metal wall tieswere located using nondestructive methods. At alllocations, the spacing of the wall ties was foundto be extremely variable, and not in conformancewith the project requirements. Random sectionsof the brick veneer were removed to examine thecondition of the ties. Corrosion on the corrugated,galvanized ties ranged from mild to severe. A fewof the ties were observed to be completely severed,thereby providing no anchorage to the backup wall(Fig. 6).Because no weep holes were observed at any ofthe relief angle locations, random removal of thebrick veneer was performed at several floor levels.Mastic was not observed at any of the relief anglesand many of the steel angles were observed to bemildly corroded on the lower levels to severely cor roded on the upper levels (Fig. 7). The lack of properflashing over the relief angles and the absence ofweep holes to direct moisture to the exterior of thewall significantly compromised the life span of thebrick veneer system on the east and west elevations.At the stacked bond sections of brick veneer,located at the center sections of the east and westelevations and at the Penthouse level on the northand south elevations, extensive areas of spalledmortar were exhibited. Ladder-type reinforcementinstalled too close to the exterior surface of the jointresulted in significant corrosion of the steel andspalling of the mortar (Fig. 8). Investigation of themetal wall ties in the stacked bond veneer revealedthe same random spacing and mild-to-severe corrosion found in other locations.Investigations were also conducted on the lowerportions of the north and south elevations.According to the original drawings, the 4 ft (1.2 m)high sections of brick veneer under the windowswere shown to be tied to the concrete unit masonrybackup walls using ladder-type reinforcement.Initially, the metal reinforcement was located usingnondestructive methods. However, to confirm thecondition of the reinforcement, the brick veneerwas removed at several locations. In all instances,the reinforcement was observed to be in good condition (Fig. 9). Nondestructive investigations wereperformed at all brick veneer locations to confirmthat the ladder reinforcement had been installed.No deficiencies were found at these locations.DEVELOPMENT OF REPAIRMETHODOLOGYBecause university officials were faced with thedaunting and costly potential of having to removeand replace 22,000 ft2 (2045 m2) of brick veneer onFig. 6Fig. 8Fig. 7Fig. 914CONCRETE REPAIR BULLETINJANUARY/FEBRUARY 2014WWW.ICRI.ORG

14 “drops” around the building, the engineer beganto investigate alternative repair options. Througha collaborative effort involving the contractor andvarious material suppliers, tests were conducted onseveral of the repair alternatives. The tests showedthat stainless steel helical wall ties installed throughthe mortar joints of the brick veneer into the concrete backup wall could properly restore theanchorage of the veneer to the concrete wall. Pulloutvalues of the helical wall ties were tested on alldrops where repairs were performed with no resultsless than 400 psi (2.8 MPa).Because the adequacy of the original corrugatedmetal wall ties was compromised at several locations, the decision was made to install the remedialwall ties at all brick veneer locations on the eastand west elevations, and at the sections of stackedbond brick located at the Penthouse level on thenorth and south elevations. Spacing of the ties wasspecified to be 24 in. (610 mm) on center horizontally and 16 in. (406 mm) on center vertically.Although the lack of protection for the steel reliefangles had yet to result in the failure of an angle,all parties agreed that this condition needed to berectified. Working closely with the contractor andthe material supplier, the engineer devised an innovative approach to holding the upper portions ofbrick veneer in place while several rows of brickwere removed to facilitate the removal and replacement of corroded steel relief angles. It was determined that staggered rows of stainless steel helicalwall ties installed just above the removal area couldhold the brick veneer in place during the shortperiod of time it took to remove and replace therelief angles, install proper flashing, and reinstallthe brick.RESTORATION PROGRAMWithin weeks of the failure, galvanized steelangles were fabricated and shipped to the site. Inan effort to provide a less-noticeable appearance tothe repairs, approximately 60% of the removedbrick units were salvaged for reuse. A new brickblend and mortar samples were matched to theoriginal materials, and full-scale repairs commenced using four swing stages. The new angleswere anchored to concrete beams using adhesiveanchors spaced at a maximum of 18 in. (457 mm)on center (Fig. 10). Pairs of holes were provided inthe angles to provide for adjustability should theexisting embedded reinforcing steel interfere withthe specified hole spacing (Fig. 11). A cover meterwas used to locate the embedded reinforcing steelprior to drilling the anchor holes. Coated copperflashing was provided over the new relief angles,along with a mortar net (Fig. 12), and vented weepunits placed in the head joints at 24 in. (610 mm)on center.WWW.ICRI.ORGFig. 10Fig. 11Fig. 12JANUARY/FEBRUARY 2014CONCRETE REPAIR BULLETIN15