Helical Solution in Concert with Restoration of Historic Olympia Theater
Ray Farrar / Method Media LLC, on behalf of Helifix, Inc.
A concerted $2.1 million restoration effort by the City of Miami and the Miami Parking Authority (which runs the theater) began with enlisting leading historic preservation and architecture design firm, R.J. Heisenbottle Architects, P.A. (RJHA) of Coral Gables, Florida, to head the restoration effort. RJHA president Richard Heisenbottle quickly involved structural engineers from Wiss, Janney, Elstner Associates, Inc. (WJE) of Northbrook, Ilinois, to conduct an initial onsite assessment.
The preliminary assessment was performed over two days in late October, 2009 to investigate the buildings distresses and design an emergency stabilization procedure, prior to installation of long-term repairs for the exterior masonry cladding. WJE collaborated with industry leading masonry repair reinforcement system manufacturer Helifix, Inc. to provide a supplementary and sustainable lateral and gravity support system for the building’s distressed veneer using its Helibeam System®.
Structural and historic challenge
During the initial assessment, WJE engineers discovered that slippage of the brick veneer lead to cracked, bulging and separating masonry. This was a direct result of insufficient vertical support and poor weight distribution; resulting in failed wall ties and lintels – often the only means of support above the windows. Due to the differential support conditions and the ten-story heights of unsupported veneer, widespread distress attributable to improper gravity support was observed including: diagonal brick cracking originating from the lintel ends, compressive failures within the second and third floor terra cotta water tables, delaminated faces of the water table projecting elements, and bowed displacement of the veneer in excess of 5 cm.
To restore the Olympia’s severely damaged sections back to a historic and maintainable condition, various areas of the building would need to be taken down and rebuilt – particularly at the building’s corners. Additionally, due to the inadequate gravity support and subsequent damage, WJE recommended installing a new support system for the exterior veneer. In seeking a solution to secure the existing masonry, while maintaining the aesthetic integrity of the historic building, WJE specified Helifix’s new Helibeam System which offered a non-invasive and sustainable solution comprised of HeliBars, HeliBond, DryFix remedial ties, and Crack Stitching.
The key focus of the Helibeam System was the implementation of stainless steel (austenitic grade 304 or 316) HeliBars that were 7 m long to create a reinforced “beam” across each spandrel level to distribute and support the structural loads across the piers and into the steel lintels and spandrel beams.
HeliBar starts as round stainless steel wire with a typical 0.2% proof stress of 500 N/mm² but after the cold forming manufacturing process that creates the helical hi-fin design, this more than doubles to around 1,100 N/mm². This means that HeliBar, with its relatively small diameter, provides substantial tensile properties to the masonry; particularly when combined with HeliBond grout which locks between the fins and bonds to the masonry.
Rounding out the Helibeam System to help with displacement, approximately 9,000 DryFix remedial ties were installed through the veneer and into the backup; thus providing lateral restraint and securing the façade.
According to WJE associate principal Brett Laureys, “The Helibeam System was specified because of its proven ability to secure existing masonry, it is fully concealed (once installed) and its flexibility allows it to be bent around corners with no loss of performance. It was also the most cost-effective stabilization method available and, with all work undertaken externally, there was minimal disruption to the upper floor tenants during this ‘emergency restoration’ phase which overcame the veneer’s lack of support, securing the structure while full renovation of the Olympia Theater was safely undertaken.”
Installation involved cutting out 45 mm deep slots in the mortar joints which were vacuumed and then flushed out with water. A bead of thixotropic cementitious HeliBond grout was laid in and the 7 m length of HeliBar was then placed in the slot. The grout-HeliBar-grout process was then repeated on top to complete the composite action of the Helibeam System. When each length of HeliBar came to its end, the next length was overlapped by 45 cm to create one monolithic run around the building; with corners kinked in at a 90° bend. The recessed Helibeam was then pointed over the top – rendering it virtually transparent to the naked eye upon completion.
Additionally, DryFix remedial ties used in tandem with Helibeam System for lateral restraint in the façade. The DryFix ties were installed simply by being power-driven into position, via a small pilot hole, using a special installation tool that leaves the end of the tie recessed below the outer face – allowing an “invisible” finish. Crack Stitching was also conducted to secure local cracking and stabilize any further movement of separating brick areas. According to STRUCTURAL’s project manager Alan Fleischer, “The Helibeam installation was easy as it’s a lot like crack stitching but in a longer run. After we completed the installation, you’d never know what was done to the building.”
Conclusion / Results
WJE’s Brett Laureys conferred in stating, “The repairs were successfully installed, meeting the client's needs of an emergency stabilization method which could be installed immediately, quickly, and inexpensively. It’s hard to compare with it as it was more cost effective than traditional stainless steel threaded rod and epoxy.”
Finally, RJHA’s Heisenbottle noted that, “The initial emergency stabilization phase is complete and the building is once again safe. The team is proceeding with the final (Phase II) work; a $10 million restoration of the theater façade and repair/replacement of the damaged terra cotta tile. The project is expected to be completed in 2011.”
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