Re: MSCAA Memphis International Airport Pedestrian Bridge A Slab Repair

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1 February 15, 2018 ANF Architects 1500 Union Avenue Memphis, TN Attn: Scott Dicus Re: MSCAA Memphis International Airport Pedestrian Bridge A Slab Repair Dear Scott, We have made two site visits to observe the damaged concrete slab of the Pedestrian Bridge A between Concourse A and the Parking Garage. The walking surface of the bridge consists of precast double-tees that have a 2 thick flange. Then a 2 thick topping slab was cast on top. At the north end of the bridge, the first double-tee on the east side cracked and parallel to the north web and the north end of the double-tee has rotated down making an unsafe condition. We recommend that this double-tee be replaced. The topping slab must be cut at the edge of the double-tee, then the welds can be cut to free the double-tee from the bridge. A new double-tee must be fabricated with weld plates to match the existing so that the new double-tee can be placed and welded in place. Then provide a psi air entrained topping slab to match existing. We recommend the architect specify a caulk joint between the new concrete and existing. Copies of the original structural drawings are attached for reference (not to scale). The contractor is cautioned that there are floors, tunnels, etc. under the roadway and sidewalks. Therefore, the contractor must be familiar with the surroundings and provide shoring as required to protect the remaining structure from damage, especially when using cranes or other equipment that would put a high load on the structure. To protect the pedestrian bridge from wheeled traffic, bollards can be installed. As an add alternate, 36 tall fixed stainless steel bollards with 4 outside diameter shall be installed at each end of each bridge (4 bollards total). Anchor bollards to the structure with four 5/8" x6" Titen HD anchors by Simpson Strong-Tie or equal. Coordinate locations with bollard base plate. Drill holes with a carbide drill bit and do not cut existing rebar. It should be noted that these bollards and their connections are not rated for Vehicle Impact and will only function as a deterrent to keep vehicles off the pedestrian bridges. 474 Perkins Extended Suite 211 Memphis, TN Phone (901) Fax (901)

2 If we can be of any further assistance to you, please do not hesitate to call. Thank you and Best Regards. Sincerely, JAMNU H. TAHILIANI & ASSOCIATES, INC. Mark Enoch, P.E. Principal Engineer DOUBLE-TEE TO BE REMOVED 474 Perkins Extended Suite 211 Memphis, TN Phone (901) Fax (901)

3 474 Perkins Extended Suite 211 Memphis, TN Phone (901) Fax (901)

4 PEDESTRIAN BRIDGE VICINITY MAP 474 Perkins Extended Suite 211 Memphis, TN Phone (901) Fax (901)

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7 INSTALLATION PROCEDURE Wabo SiliconeSeal Joint System Silicone Expansion Joint Sealant for Bridge & Highway Applications A. General The work shall consist of furnishing and installing a Wabo SiliconeSeal joint system in accordance with the details shown on the plans and the requirements of the specifications. Placement of the Wabo SiliconeSeal joint system shall consist of proper surface preparations, material and application of materials. B. Joint Preparation The concrete joint interface must be clean (free of dirt, coatings, rust, grease, oil and other contaminants), sound and durable. New concrete must be cured (minimum of 14 days) and all latinance removed. Durable Concrete- sound and durable concrete should have a cap pull-off strength that meets or exceeds ACI 503R, Appendix A. Unsound Concrete Loose, contaminated, weak, spalled, deteriorated and/or delaminated concrete must be removed to sound concrete and repaired prior to placement of Wabo SiliconeSeal. Any patching materials must be approved by manufacturer prior to use. Joint interfaces should be sandblasted to remove any residue that may be present. It is recommended that the sandblasting operation be performed in two steps, one step per joint interface. The joint should be blown cleaned using compressed air (>90 psi). The compressed air shall be free of moisture and oil. The joint interfaces should be checked for cleanliness. Should any contaminates remain, then the joint must be re-blasted and blown clean. To insure cleanliness, each joint interface should be wiped clean with a clean rag without solvents to remove any dust remaining after sandblasting. C. Backer Rod Placement A closed-cell, expanded polyethylene foam rod is recommended. The rod acts as a bond breaker, preventing the Wabo SiliconeSeal from bonding to the bottom of the joint and preventing the flow of the material through the joint itself. The size of the backer rod should be 25% greater than the joint opening to be sealed. The backer rod should be positioned in the joint such that the top of the rod is one 1 (25 mm) below the riding surface. Bridge & Highway Aug of 2

8 INSTALLATION PROCEDURE Wabo SiliconeSeal Joint System Silicone Expansion Joint Sealant for Bridge & Highway Applications D. Mixing of Wabo SiliconeSeal The Wabo SiliconeSeal should be applied using proper dispensing equipment such as Johnston or Graco/Pyles extrusion pump for 10-gallon kits or dual component pneumatic powered double piston guns for oz cartridges. Regardless of equipment used, the material shall be mixed using 3/4 dia. 20 element static mixer or greater. Caution: Do not allow material to remain static in mixer longer than five (5) minutes without changing to a new static mixer. Uncured sealant can be removed with the use of solvents such as naphtha or mineral spirits E. Wabo SiliconeSeal Placement Application of the Wabo SiliconeSeal should be in one direction only and from the bottom of the joint up. The Wabo SiliconeSeal shall be applied to a thickness of ½ (13mm) minimum while not exceeding 5/8 (16 mm) and maintaining a ½ (13 mm) recess from the riding surface. Wabo SilconeSeal will begin to cure and form a surface skin within 20 minutes of application. The seal will be ready to accept traffic generally within one hour after installation Bridge & Highway Aug of 2