LANS0004_LRT_LansingMooresPavilionInspection.docx

May 22, 2017

Mitch Whistler Assistant City Engineer City of Lansing, MI 732 City Hall 124 W. Michigan Ave Lansing, MI 48933

Re: Moore’s Park Pavilion – Inspection Summary of Finding and Recommendations

Dear Mr. Whistler:

The Mannik & Smith Group, Inc. (MSG) is very excited to work with the City of Lansing on this very important project. The purpose of this project was to inspect the pavilion at Moore’s Park in Lansing, MI for structural integrity and provide recommendations for City action. The pavilion was recently closed and boarded up to prevent entry into the facility.

PAVILION HISTORYThe pavilion at Moore’s Park consists of a timber open frame structure built on top of a reinforced concrete supported slab structure. The timber open frame structure consists of timber trusses supported on 4x6 timber columns. The reinforced concrete supported slab structure consists of a 3 inch concrete slab supported on two interior concrete girders and exterior concrete walls with stone exterior facade. The two girders are supported at midspan with concrete columns.

Existing plan for the pavilion timber open framed structure are on file, however, the lower reinforced concrete supported slab structure were not found on file. Although existing plans for the lower reinforced concrete supported slab structure were not found in the City’s records, the exposed square reinforcement used in the slab and the columns suggest that the concrete structure was built prior to the 1940’s. The timber open framed structure plans have a design date of 1974. There are also plans for partial removal of the 1974 structure illustrated on plans dated 1992.

Park Maintenance crews closed the pavilion and boarded up the sides of the structure to restrict access in early May 2017.

INSPECTION AND FINDINGSMSG performed a visual inspection of the pavilion on May 15, 2017. The lower concrete structure was accessed from the door on the North side of the building. The top concrete deck and timber structure were inspected from the outside of the pavilion, through an inspection port and by looking over the plywood barrier.

The reinforced concrete supported slab structure, concrete wall, concrete girders and concrete columns are all showing signs of distress. The columns and top slab have large spalls with exposed and deteriorated concrete and reinforcement. Deteriorations was witnessed over approximately 70% of the slab underside. The top side of the slab has long, 1/16” open cracks that appear to be directly over the main support girders as well as other areas over

2193 Association Drive, Suite 200, Okemos, Michigan 48864 Tel: 517.316.9232 Fax: 517.316.9233 www.MannikSmithGroup.com

THE MANNIK & SMITH GROUP, INC. 2 LANS0004_LRT_LansingMooresPavilionInspection.docx

approximately 10% of the slab surface. The deck edges under the timber pavilion columns and over the concrete masonry unit (CMU) filled window openings also have large spalls with exposed reinforcement. The concrete walls, supporting the concrete slab and the timber pavilion structure overhead, have only minor signs of deterioration. The interior support girders appear to be in good conditions except for an open 1/8” longitudinal crack in the East beam line adjacent to the concrete column. The concrete columns have large spalls along the edges of the column. The column vertical and tie reinforcement is exposed, and bottom shear tie-bar confinement steel is completely deteriorated to 100% section loss. The timber open frame structure is showing distress in a few areas. The West column line is racking toward the north. The amount of movement was measured 1/2” over 2 feet. This equates to approximately 2.5 inches over the 9’ column height. The Northeast corner column has lost its column base and is floating. Other columns are twisting, splitting and showing signs of distress under the apparent movement. Multiple columns have deteriorated concrete under the base of the timbers causing up to 50% loss of bearing under the timber. CONCLUSIONS The level of deterioration observed has compromised several main structural elements resulting in reduced safe load carrying capacity. In our opinion, the structure is not safe for use by the public. The amount, location and type of deterioration found in the structure during the site investigation will likely result in a reduced live load capacity as well as concern for stability under high winds. The apparent cause for the concrete distress is due to moisture infiltration into the deck causing deterioration of the reinforcing steel and deck concrete over time. When steel deteriorates, pack rust develops and causes clear cover over the bar to spall away from the structure. The lack of clear cover further exposes the steel reinforcement to moisture and accelerates the deterioration of the bar. Multiple bars are deteriorated to 100% loss in the concrete deck. A load rating of the existing deck can be performed; however, it is likely that the results will show a dramatic reduction in live load carrying capacity as a result of the observed deterioration. The apparent cause for the distress in the open timber structure is movement under wind loads and natural deterioration of timbers over time due to exposure to the elements. The timber structure was built in 1974 and is partially enclosed by the roof. The columns bases, timber rails and column based that are more exposed have the highest level of deterioration. The most severe deteriorations is in the columns that are not braced longitudinally for movement. The concrete slab under the timber columns is also deteriorated to a point where the amount of bearing available is minimal. The observed bearing areas under the columns have been reduced resulting in high stress concentration of load. RECOMMENDATIONS MSG recommends that pavilion remain closed until repairs can be made to the structure. The following are various recommended repair and replacement alternatives: Lower Concrete Supported Slab Structure:

1) Repair option: - Overcast or replace the concrete columns and provide new shear and vertical reinforcement. - Overcast or replace the existing beams and provide new shear and moment steel. - Re-support the pavilion timber columns to rest directly on the concrete walls. - Remove and replace the concrete deck. The Timber Open Frame Structure would need to be

temporarily supported or removed prior to work. - Overcasts and concrete deck will need to be designed and detailed for current structure use.

THE MANNIK & SMITH GROUP, INC. 3LANS0004_LRT_LansingMooresPavilionInspection.docx

2) Fill option: - Fill the lower concrete supported slab structure with structural fill. - The structure will need to be evaluated to see if a geofoam, light weight concrete, aggregate,

flow-able fill of some combination of those should be used to avoid settlement issues with the building.

3) Demolition Option: Removal of entire structure and the Timber structure on top.

Timber Open Frame Structure A) Repair Option: - Temporarily support timber structure. - Replace timber columns and hardware at base and truss connections. - Replace timber railings - Add cross-bracing between columns. - Rehabilitation will require structural design and detailing of the entire existing structure under the

current building code.

B) Replacement Options: - Many options are available for the type size and location of a new pavilion.

MSG would like to discuss the future plans for Moore’s Park and the pavilion with the City. An engineer’s opinion of costs of the options presented above can be prepared for discussion with the City if requested. A cost benefit analysis should also be considered to examine costs over time for the rehabilitation options.

MSG appreciates the opportunity to work with the City on this very important project and looks forward to serving the City in the future. Please, do not hesitate to contact the undersigned if you have any questions or if you would like additional information.

Sincerely,

Matthew T. Mikolajczyk, P.E. Christopher M. Zangara, P.E. Project Manager/ Project Engineer Engineering Manager

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