1118 and 1120 Structural Assessment and Repairs 2022.pdf

July 29, 2022

To: Willie Willenbrink

From: Grant Thorson, PE

RE: Structural Assessment for Dormitory Buildings 1118 and 1120

LBYD Federal (LBYD), previously known as North Wind Infrastructure and Technology, through coordination with the 611 CES, Pacific Air Forces Regional Support Center, was asked to inspect and provide structural assessments and short-term repair recommendations for the dormitory buildings 1118 and 1120.

1. Introduction

This inspection and report are performed to comply with previous recommendations that structural inspections and assessments should occur regularly to track known deficiencies and identify changes in condition of the structures. This report has the specific purpose of providing repair recommendations that will help mitigate immediate concerns and extend the structural life of the buildings for the short term. The short-term goal being moderate renovations for the continued use of buildings 1118 and 1120 for up to 10 years while new facilities can be constructed. This inspection and repair recommendations are limited to structural components of the buildings.

The buildings were recently inspected in 2017 and 2020. The inspection in 2017 was an overall building inspection performed by the USACE and included recommendations for architectural, mechanical, electrical, and structural components. The inspection in 2020 was performed by

North Wind (LBYD) and was limited to structural components.

In preparation for this task, LBYD reviewed the report produced by the US Army Corps of

Engineers (USACE) dated 4 August 2017 titled Engineering Assessment of Dormitory Buildings, Wake Island and the most recent assessment provided by LBYD. LBYD retains previous concurrence with the referenced assessments that these buildings should be removed from service and replaced as soon as possible. All the previous observations and analysis appear correct and should still be considered current.

The Wake Island Installation Design Guide indicates that the facilities should be designed for an expected lifespan of 40 – 50 years. These dormitory buildings were built in 1963 and at 60 years old have exceeded their design life.

The inspections occurred during a site visit in July of 2022. The buildings have recently been removed from use due to mold and overall degradation. The building interiors were mostly demolished as part of mold mitigation and in preparation for anticipated updates.

Inspection of the buildings included visual inspection of the exterior of the structure and visual inspection of the interior with exceptions where interior finishes were not removed.

2. Observations

2.1. General

The type of construction is cast in place concrete beam and column frame with continuous concrete foundation walls and concrete stem walls at the exterior wall of each bay. The bathroom floors of the upper level is a cast in place concrete slab. Some bays of the structure are cast concrete or filled using masonry block and appear to act as shear walls. The condition of structural components of the building varies greatly throughout the buildings. To a large degree the condition of the concrete and rebar is directly connected to the presence and exposure to moisture with the exterior members showing degradation. Interior members show little to no degradation except for concrete surrounding the main floor pipe chases.

- The buildings appear to be in similar condition as previous inspections with minimal expected continued spalling and cracking.

- Several of the interior walls have experienced severe termite damage. This damage is not throughout, rather is localized, and is typically found on the 1st level.

- There were several significant rain storms during the period of the inspections and several of the rooms had some standing water inside the building. The source of the water was not always easy to determine but generally appeared to penetrate the building through the wood framed portions of the exterior walls. In some locations it appears water may be penetrating the building through cracks in the concrete ceiling or walls.

- Humidity in the building is high as a result of the outside climate, water intrusion, as well as poor ventilation. This humidity and associated condensation has also affected the existing structure as the moisture exploits the already susceptible high chloride concrete and allows corrosion of the reinforcing bars.

2.2. Structural Components

In order to define and quantify short term repairs, the inspection included documentation of individual member condition. Because previous inspections described the degradation in general terms, this inspection is not able to specifically identify changes to members. This inspection designates unique ID’s and has photographed all observed damage so specific repairs can be coordinated and ongoing inspections can track specific problem areas. These photos can be found in the attached photo log.

In order to identify each location, a concept floor plan of the buildings was developed and each member can be identified using the column lines and elevation information shown here.

Figure 1 Buildings 1118/1120 Floor Plan

Information on the condition of each building by member and location can be found in the following tables. The tables include column line location corresponding to the concept layout in

Figure 1, elevation information, a description of the member and condition, damage type, and the severity/priority of the needed repair. More information on repairs is found in Section 3.2.

3. Recommendations

3.1. General

As previously stated, the goal for these buildings is that they be renovated for an additonal short term life of up to 10 years. It appears the buildings can be relied on to function structurally for another 10 years based on:

- There are no observed deflections or movements of members

- There is little to no sign of tension or compression related cracks

- The structure has multiple redundancies

- The short-term repairs recommended here will repair, mitigate, and or slow the continued degradation of the structures

There are however inherent risks with extending the life of the structures. They are beyond their design life and are showing signs of degradation. As previously recommended, the structures should be inspected regularly to monitor for changes in condition. The structures should also be inspected if any severe event such as earthquake, tsunami, or rogue wave should occur. Ongoing inspections should look for:

- structural movement or deflections

- inspect and document the status of repairs

- look for additional damage

- monitor progression of existing damage

- provide recommendations to repair or mitigate new damage as it may occur.

3.2. Repairs

In order to minimize continued corrosion of rebar and concrete damage, repairs identified in the tables above should be performed. These repairs reflect the execution of previous short term course of action recommendations and are intended to extend the life of the building while a new facility can be built. Several cycles of inspections have identified that these buildings should be replaced. These repairs do not bring the buildings up to code, nor do they eliminate risk associated with occupying the outdated structures. General recommendations are:

- Moisture: Ensure the structure and concrete is sealed against moisture intrusion. Ensure the roof membrane is in good condition. Coat the exterior walls to seal all minor concrete cracks against moisture intrusion.

- Treat all wood framing for termites.

In the tables in Section 2.2 include columns for damage type and priority. The priority for repairs is based on judgement and includes the observed width and depth of the crack, significance of the structural member, and the overall extent of damage to the individual member. The damage type A, B, C designations are defined as:

A- Cracks narrower than ¼”. Anticipated repair is to seal the crack in place.

B- Crack is wider than ¼”. Anticipated repair is to remove loose concrete and seal the crack in place

C- Crack is wider than ¼”. Concrete may be missing. Rebar may be exposed. Anticipated repair is to remove loose or broken concrete, clean rebar of rust scale, treat rebar with rust inhibitor/converter, and grout back to form.

These designations are based on field observations. Each repair will require field judgement and determination to modify the repair as a change of conditions may be exposed as the repair process is underway.

3.3. Products

There are many product options that can be used in the recommended repairs. Here are several along with a brief description of the purpose for each. Similar products may be substituted.

3.3.1. Crack Sealant Type A and B Repairs

General minor cracking (Severity/priority level less than 4) does not need to be specifically repaired. These cracks should be sealed as part of the general building paint or coating system on the exterior of the building. On the interior of the building no specific effort is needed.

Other cracking requiring sealant should be accomplished to seal the cracks from additional moisture to protect against progression of corrosion and associated cracking. For primary structural members; columns, shear walls, and floor beams; the repair should be made by epoxy injection using a product such as Sikadur Injection Gel. For secondary structural members, foundation walls and stem walls, the repair should be made using SikaFlex

Concrete Fix. In each case the product must be applied following manufacturer recommendations.

For Type A repairs clean the cracks and adjacent surface and seal the cracks in place. Type

Be repairs are designated as such due to the width of the crack and the possible need to clean out the crack of debris. In some cases Type B repairs may require the removal of loose concrete.

3.3.2. Concrete Repair Type C Repairs

Several locations have missing concrete or have cracked concrete that is severely broken and will need to be grouted back to form. In these locations the repair should consist of the following:

- Removal of loose or broken concrete

- Needle scaling or wire brushing to remove any loose scale on existing rebar

- Sealant of any exposed cracks if remaining

- Treatment of existing rebar with a corrosion inhibitor such as Sika Armatec 110 EpoCem

- Grout the concrete back to form using appropriate mortar mix such as SikaQuick VOH

- Coat the area to match adjacent surface

4. Conclusion

Building 1118 and 1120 appear structurally suitable for occupancy for the next 10 years provided recommended repairs are made to mitigate ongoing corrosion and damage. This recommendation is part of a stop gap measure to provide housing for base personnel while a new facility can be constructed. This recommendation and repairs do not bring the buildings to code compliance rather will provide a short term solution while an updated facility can be constructed.

Thank you for the opportunity to visit Wake Island and provide this report. Please let me know if you have any questions regarding these contents or findings.

Signed.

Grant Thorson

Project Engineer