B08_Attachment_12_Investigation_and_Stabilization_-_2008.pdf

PERRY’S VICTORY AND

INTERNATIONAL PEACE MEMORIAL

Investigation

Put-in-Bay, South Bass Island, Ohio

Final Report

12 February 2008 WJE No. 2007.1047

Prepared for:

National Park Service, Denver Service Center

Prepared by:

Wiss, Janney, Elstner Associates, Inc.

PERRY’S VICTORY AND

INTERNATIONAL PEACE MEMORIAL

Harry J. Hunderman, FAIA

Michael J. Scheffler, PE

Paul E. Gaudette

Una M. Gilmartin, PE

Final Report

WJE No. 2006.3711

Prepared for:

National Park Service, Denver Service Center 12795 West Alameda Parkway Denver, Colorado 80225

Prepared by:

Wiss, Janney, Elstner Associates, Inc.

330 Pfingsten Road Northbrook, Illinois 60062

847.272.7400 tel | 847.236.0866 fax

TABLE OF CONTENTS

Executive Summary

Introduction

Background

Methodology

Description

Summary of Prior Conclusions and Recommendations

Observations

Fascia

Soffit

Observation Deck

Penthouse

Upper Plaza Structure

Figure 1-1 through 1-49

Structural Analysis and Load Testing

Structure of the Observation Deck

Structure of the Upper Plaza

Load Testing of Upper Plaza

Figures 2-1 through 2-12

Discussion and Conclusions

Observation Deck Structure

Upper Plaza Structure

Repair Recommendations and Cost Estimate

Monitoring

Appendix A – Stabilization and Temporary Repairs - As-built Drawing

Appendix B – Concrete Core Analyses

Appendix C – Upper Plaza Load Test

Appendix D – Repair Recommendation and Cost Estimate

PERRY’S VICTORY AND INTERNATIONAL PEACE MEMORIAL

EXECUTIVE SUMMARY

WJE previously completed a condition assessment of the memorial as documented in a report entitled, Perry’s Victory and International Peace Memorial: Exterior Condition Assessment, dated 12 February

2007. The purpose of this supplementary investigation was to develop information necessary to refine the scope of recommendations for repair made based on the previous investigation. Access to the capital and the dismantling of some components of the memorial required for the investigation provided an opportunity to implement some of the stabilization recommendations that were made in 2006 after the initial investigation. These stabilization measures were designed to address cracked and dislocated granite fascia and soffit panels, and to minimize the water penetration at the Penthouse and Observation Deck.

The site investigation included removing cores from the concrete structure of the capital and Upper Plaza for evaluation of freeze thaw distress, as well as closer examination of components of the capital including the granite fascia, soffits, and parapet wall, Observation Deck concrete, Penthouse walls and roofs, and Upper Plaza structure.

The removal of the original granite pavers and setting bed resulted in a reduction of the dead load of the structure approximately equivalent to a 100 psf live load, which is the code prescribed live load. Also, installation of new temporary waterproofing at the Observation Deck will presumably mitigate the development of additional freeze thaw deterioration of the concrete in the short term. Therefore, continued use of the Observation Deck can be allowed, provided that routine monitoring is performed to evaluate the effectiveness of the waterproofing and to observe the development of new granite cracks and displacements.

Given the fact that there is no acceptable method for performing an engineering analysis of severely damaged concrete structures, it is difficult to determine whether the structure of the Observation Deck, in its current deteriorated state, has sufficient strength to reliably resist imposed loads. This is not the same as saying the structure definitively does not have sufficient strength to reliably resist imposed loads.

However, based on the examination of the numerous concrete cores removed from the structure, the extent of distress is considered severe enough that the concrete structure needs to be repaired to bring it to a state in which it is considered to have reliable strength.

For the long term, the only method that will bring the Observation Deck to a state of reliable performance is to replace the freeze thaw damaged concrete with new concrete. The most straightforward and likely cost effective method for this is to shore the existing granite fascia and soffit panels, remove the granite panels at the inside of the fascia and coping stones and store them for reuse, and remove and replace the freeze thaw deteriorated concrete and integral reinforcing steel. Based on the results of the investigation, this will most practically be accomplished by removing the entire concrete spandrel beam and the adjacent slab for its full depth, and removing the slab to lesser depths nearer the Penthouse wall. For this work the cracked fascia stones soffit stones can be shored and pinned to the repaired slab and spandrel

Perry's Victory and International Peace Memorial beam. After removals a new spandrel beam and slab will be cast against the back of the granite soffit panels and fascia panels.

Regardless of the extent of structural repairs completed at the Observation Deck, the long term survival of this and other components of the memorial is dependent on the installation and maintenance of an effective waterproofing system. In particular, continuity of waterproofing from the roof under the Lantern to the granite fascia of the Observation Deck is critical. However, it is not feasible to install waterproofing behind the exterior vertical surfaces of the Penthouse because the concrete structure is integral with the granite cladding. The existing waterproofing and work required are discussed in detail in our Exterior

Condition Assessment report dated 12 February 2007.

Until repairs are made to the Observation Deck and shaft to eliminate the potential for granite to fall onto the Upper Plaza, public access should be limited to accessing the memorial through the existing canopy.

For structural evaluation of the Upper Plaza, a load test was completed at a representative area. One of the beams observed to have no visible distress did not meet ACI acceptance criteria during load testing, while other components did meet the criteria. Based on these test results, it is likely that, if tested, some of the elements outside of the test location would not meet the ACI acceptance criteria. Therefore, after long term repairs to the memorial are complete and public access to the Upper Plaza is possible, either 1) the load rating of the structure should be reduced; 2) the structure should be shored or reinforced after making selective repairs to the waterproofing to reduce water leakage and freeze thaw deterioration; or 3) the

Upper Plaza structure should be demolished and replaced, together with the waterproofing and paving systems. The installation of shoring or reinforcement as a remedial measure has been shown to be effective for several years for many structures. Further study is required to determine the extent of shoring needed to support the beams, girders, and slab areas of the plaza.

Based on this investigation and the investigation completed in 2006, a scope of work for the repair of the memorial has been developed conceptually and cost estimated. This scope of work generally includes substantial structural repairs to the capital at the Observation Deck, repairs to the waterproofing and masonry at the Penthouse, repointing and masonry repairs to the shaft, and repairs to the structure and finishes at the Upper Plaza.

To address the NPS desire to phase the recommended long term repairs over several years, we have developed the cost estimate to include the following:

Phase I (Base Cost) – This work includes the long term repairs from the granite soffits of the capital to the top of the Lantern. Estimated cost of $5,073,000.

Phase II (Alternative 2) – This work includes repairs to the echinus and shaft, or all work from the granite soffit to the Upper Plaza. Estimated cost of $6,645,000.

Phase III (Alternative 3) – This work includes repairs to the Upper Plaza, including removing and replacing all or some of the paving and waterproofing systems as well as repairs to the site walls and features. Estimated cost of $2,295,000 to 7,942,000 depending on the scope of work.

Until long term repairs can be initiated, the effectiveness of the temporary repairs and stabilization completed as part of this project is dependent on a rigorous monitoring program. Such a monitoring program should include frequent park staff condition surveys and well as periodic surveys by engineering specialists.

INTRODUCTION

Background

At the request of the National Park Service Denver Service Center, Wiss, Janney, Elstner Associates, Inc.

(WJE) conducted supplemental investigation and analysis, and completed temporary repairs, for the

Perry’s Victory and International Peace Memorial in Put-in-Bay, Ohio.

WJE previously completed a condition assessment of the memorial on behalf of the National Park

Service, as documented in our report entitled, Perry’s Victory and International Peace Memorial:

Exterior Condition Assessment, dated 12 February 2007. The purpose of this investigation was to develop additional information necessary to refine the scope of recommended repairs, to confirm the conclusions derived from the condition assessment, and to confirm existing condition details for the development of design documents for repairs.

Stabilization repairs implemented in coordination with this investigation were performed as a design-build project with WJE by Cleveland Marble, Inc., of Cleveland, Ohio. Cleveland Marble also provided contractor support for access, inspection openings, core removal, and related investigation tasks.

Estimating services were provided by Don Todd Associates, Inc., of San Francisco, California.

Methodology

WJE completed our previous report entitled Perry’s Victory and International Peace Memorial: Exterior

Condition Assessment, based on a field investigation conducted in October of 2006. During review of the report findings with National Park Service representatives, immediate stabilization measures and additional investigation were discussed. The scope of the additional investigation and temporary repairs documented in this report was developed based on that discussion.

Investigation and documentation were performed in coordination with implementation of temporary repairs. The investigation included visual inspection and additional nondestructive evaluation by sounding, impact-echo testing, and ground penetrating radar techniques. In addition, concrete cores were removed from selected locations at the Observation Deck and Upper Plaza for laboratory evaluation to determine the presence and extent of freeze thaw deterioration.

Temporary repairs completed by Cleveland Marble in coordination with the investigation included repairing the roofs of the Penthouse to retard water infiltration; replacing the existing Observation Deck paving and waterproofing; repair/pointing of the Penthouse to retard moisture penetration; stabilization of cracked fascia and soffit panels; temporary enclosures for the area of granite fascia where a piece had fallen; temporary enclosure of the beam(s) supporting the soffit panels to prevent public access; and other miscellaneous stabilization measures for the fascia panels including determining the size, location, and installation of anchors, temporary clamping, etc.

During the initial survey, severe freeze thaw damage to the Upper Plaza concrete structure was observed, resulting in significant uncertainty as to the extent and severity of diminished capacity of the existing structural system. Structural load testing was therefore performed as part of this study to evaluate the current capacity of the concrete structure to support loads, and to determine if repairs or replacement of the plaza structure is required at this time. Load testing and structural analysis of a representative area of the Observation Deck were performed in an effort to evaluate the extent to which the capacity of the reinforced concrete structure has been diminished by freeze thaw deterioration of the concrete, and to evaluate whether the structure has sufficient current strength to reliably support code prescribed loads.

Based on the investigation and analysis, conceptual repair/restoration options developed following the

2006 investigation were revised and evaluated for constructability. In addition, recommendations were developed for monitoring the capital, Penthouse, and Upper Plaza. A revised, independent Class C

Construction Cost Estimate for repair was prepared based on the revised recommended design, following current NPS standards.

Regardless of the extent of structural repairs completed at the Observation Deck, the long term survival of this and other components of the memorial is dependent on the installation and maintenance of an effective waterproofing system. The existing waterproofing and work required are discussed in detail in our Exterior Condition Assessment report dated 12 February 2007.

Description

The following description of the memorial is adapted from that provided in our February 2007 report.

Please refer to our previous report for a detailed description and history of the memorial.

The Perry’s Victory and International Peace Memorial is located on the isthmus of South Bass Island adjacent to the city of Put-in-Bay, Ohio. The memorial rises to a height of 352 feet above Lake Erie, with the Observation Deck at a height of 317 feet above lake level. The memorial is in the form of a Doric column set on a concrete foundation, with the exterior face clad with ashlar cut, Milford Pink granite quarried near Milford, Massachusetts. The granite is set against an unreinforced concrete backup.

Coursing consists of seventy-eight rows of granite topped by a seventy-ninth or necking course, which is comprised of solid blocks the full thickness of the wall. Above the necking are three corbelled courses of granite with concrete backup that comprise the echinus. The fascia or parapet wall of the Observation

Deck creates the abacus. The fascia, soffits, coping, and interior face of the parapet are also of Milford

Pink granite supported by a concrete cantilever structure. Within the parapet is the Observation Deck and granite-clad elevator Penthouse. The granite roof of the Penthouse is surmounted by a bronze, eight-legged Lantern, which incorporates a glass skylight and electric lights.

Surrounding the memorial column is a raised Upper Plaza paved with granite and brick pavers. The

Upper Plaza is raised above the natural grade level on a concrete structure. The perimeter of the upper plaza slab drops down to accommodate the planters on the east, west, and south sides of the plaza.

Perimeter retaining walls and an earthen embankment enclose the Upper Plaza on three sides; at the north end, a broad granite staircase leads from the Upper Plaza to the lower plaza. The Upper Plaza perimeter retaining walls consist of granite cladding with interior concrete fill, and the Upper Plaza structure consists of cast in place reinforced concrete columns supporting reinforced concrete beams and slab. The lower plaza is on grade and is paved with granite pavers. At the center of the basement is the concrete foundation of the memorial column.

The interior of the memorial column has a rotunda at the first floor. A pair of stairs rises from the rotunda level within the thickness of the column wall. From the second floor elevator landing, the elevator rises to the Penthouse level at the center of the column, and the main concrete staircase spirals upward around the open elevator shaft.

Summary of Prior Conclusions and Recommendations

The purpose of the exterior condition assessment completed in 2006 was to develop a scope of work for the comprehensive repair of the memorial, based on information from previous studies and from investigation that could be completed within the time frame available.

The exterior condition assessment completed in 2006 revealed the following conditions:

The Penthouse roof and walls readily allow water to penetrate the structure readily.

The Observation Deck waterproofing is ineffectively configured, allowing water to penetrate the concrete structure of the capital.

Saturation of the concrete structure of the capital has led to freeze thaw related deterioration of the concrete; this type of deterioration is likely to continue or accelerate if conditions remain unchanged and water is not prevented from penetrating the concrete structure of the capital.

Deterioration of the concrete has led to expansive pressures on the granite fascia and soffit panels, causing cracking of the granite. This deterioration, in combination with restraint provided by the through-structure anchors in the soffit panels installed in the 1980s, has led to cracking of the soffit panels, particularly at the southwest corner.

Most of the cracking of the fascia and soffits that can be observed today has occurred since the work was completed in 1980s.

Cracking and distress to the granite fascia and soffit panels will continue unless an effective barrier to water penetration can be implemented.

In addition to the fascia panel from which a portion fell, an additional six fascia panels (two on the south, three on the east, and one on the west) exhibit similar cracking and appear to be unstable, and, therefore, are considered to be imminently hazardous.

Silicone sealant (caulk) installed during the 1980s in the granite joints of the column is in fair condition. Deficiencies in the sealant joints from original installation and localized deterioration, as well as offsets between granite units and the entasis of the shaft wall, permit water to enter the structure readily. These conditions also prevent water from escaping. White mineral deposits have developed at the locations where water exits the wall.

Incipient spalls are present in granite units of the shaft, some of which may be imminently hazardous.

The concrete structure of the Upper Plaza exhibits freeze thaw damage throughout. Load testing is required to determine the current load capacity and to determine if the Upper Plaza structure requires replacement.

In addition, findings of the exterior condition assessment indicated that additional investigation was necessary to clarify the condition of the concrete structure of the capital and Upper Plaza, and to confirm that the scope of long term repairs developed in the prior study was appropriate and necessary. This additional investigation is the focus of the current study and this report.

As part of the prior exterior condition assessment, repair recommendations were also developed based on the research and investigation performed. Because of the apparent accelerating cracking and deterioration of the capital fascia and soffit panels, some immediate stabilization was recommended until long-term repairs can be designed and implemented. For the safety of the visitors and staff, and to allow public access to the Observation Deck, the following specific short-term measures were recommended:

Remove or stabilize the six cracked fascia panels.

Stabilize the cracked soffit panels at the southwest corner of the capital.

Maintain the current public access restrictions at the site, which include preventing access to the

Upper Plaza.

Prevent visitors from congregating on the steps to the Upper Plaza, or shore the concrete stringers beneath the granite steps.

Erect a construction canopy over public access at the entrance to the memorial.

In addition, implementation of temporary short term measures to prevent additional water penetration of the Penthouse and capital was recommended to limit ongoing deterioration from continued water penetration and freeze thaw damage.

OBSERVATIONS

Observations during the investigation of the fascia, soffit, Observation Deck, Penthouse roof, and Upper

Plaza are described below. A description of the temporary stabilization repairs installed as part of the work of this study is provided following the observations for each area of the memorial. The temporary stabilization repairs are described in detail in Appendix A.

Fascia

Observations of Fascia Cracking and Displacement Close-up inspection of the granite fascia panels was performed at the south, east, and west elevations by means of suspended scaffold (swing stage) access. See Figure 1-1. Examples of cracked panels are shown in Figures 1-2 through 1-4. As observed in our previous condition assessment, four of the thirteen panels at the south elevation are cracked; three of these panels have cracks that could potentially result in portions of the panels not being adequately supported on the soffit panel below. See Figure 1-5 for locations of the observed cracking, and for the numbering system used to identify the panels. Five of the thirteen panels at the east elevation are cracked; three have cracks that could potentially result in portions of the panels not being adequately supported on the soffit panel below. Ten of the thirteen panels at the west elevation are cracked; five have cracks that could potentially result in portions of the panels not being adequately supported. In addition, one panel on the west elevation that was damaged by lightning in the 1920s has cracks and has displaced to an extent that could potentially result in portions of the panels not being adequately supported.

Displacement was noted at the crack location at Panel 1 on the west elevation, which had been previously struck by lightning and repaired. Displacement was also noted along the edge of Panel 13 on the west elevation. In addition, displacement was noted at the crack location on Panel 4 on the south elevation.

Stabilization Repairs Stabilization repairs performed as part of this study consisted of the installation of through face anchors at cracked panels. Eleven granite panels, including three panels on the east, three panels on the south, and five panels on the west, were stabilized. The anchors used in the stabilization repairs consisted of a stainless steel threaded rod set in epoxy, with a stainless steel plate, nut, and washer on the exterior face of the panel. At locations of severe freeze thaw distress in the concrete back-up (at seven panels: three on the south and five on the west), the anchors were supplemented with stainless steel straps to provide additional redundant support. Refer to Figures 1-6 and 1-7 for illustrations of stabilization repairs. Details for the stabilization design can be found in Appendix A. Refer to Figure 1-8 for locations of stabilization repairs installed to address cracked panels with potential of being inadequately supported.

Soffit

Observations Because of the positioning of the scaffolding on the south and west elevations of the fascias, it was possible to perform additional inspections of the soffits with closer access than was available in the previous study, although hands-on inspection was not possible. Based on this additional inspection, there were indications that additional cracks had developed and that additional downward displacements had occurred since the investigation in 2006, as shown in Figure 1-9. Documentation of distress was updated.

Also, observations revealed that existing granite plug covers over previous repairs had displaced and appeared to be loose at some locations. An example is shown in Figure 1-10.

Stabilization Repairs Because of the concern over possible additional displacements, supplemental supports were installed at the southwest and southeast corner soffits. The stabilization repair consisted of installing an aluminum beam and hanger assembly supported from the top of the parapet wall above. The repair beams were positioned to capture and support cracked portions of the granite soffit and, where possible, loose plug covers. Refer to Figures 1-11 through 1-14 for illustrations of this repair. Details for the stabilization design can be found in Appendix A.

Observation Deck

Interior Parapet Granite Panels One fascia panel was removed at the southwest corner (the fourth panel from the south on the west side).

See Figure 1-15. The original granite panels on the inside of the parapet walls are about 3 inches thick and are currently about 2 inches away from the original concrete beam. This space between the concrete beam and the granite panel was filled with mortar. The structural concrete beam was covered with coal tar pitch waterproofing. The mortar fill behind the fascia panels was observed to be severely deteriorated, presumably as a result of freeze thaw damage, and could be readily removed by hand. See Figure 1-16. It also appeared that the granite panels have displaced outward (pushed out), presumably from expansion of the concrete due to freeze thaw action. Currently the face of the granite panels is approximately flush with the coping above. The coping stones have a drip edge cut underneath the inside surface and there is evidence that the inside fascia stones were originally set behind this drip edge.

Structural Slab at Observation Deck The four inch thick granite paving stone and approximately four inches of mortar setting bed were removed from the entire Observation Deck, exposing the topping slab that was installed on top of the original structural slab in the 1980s. Observations are summarized in Figure 1-17. This process exposed the existing four drains, one at each corner, that were also installed during the 1980s work. These drains included a drain body cast into the topping slab. A clamping ring was bolted to the drain body to hold the waterproofing in place. This clamping ring included a threaded opening. A pipe threaded into this clamping ring held up the surface drains to the level of the granite paving. Because of the way this pipe was installed, water that penetrated the surface of the granite paving and percolated down to the waterproofing membrane level could not flow into at the four drains because of a lack of weeps at this level. In addition, the pipe installed during the 1980s work projects into the cast in place drain body, leaving a joint between this pipe and the drain body. This potentially allows water to enter the concrete structure between the pipe and the drain body. See Figures 1-18 and 1-19. In addition, constrictions in the downspouts at the base of the column prevent water from flowing freely, resulting in occasional ruptures of the pipe.

Because this drainage system was cast into the surface of the topping slab and not into the structural slab, it was decided not to remove the entire topping slab as draining water from the Observation Deck during the investigation would not be easily achievable. Instead, inspection openings were made in the topping slab to expose the structural slab as noted below.

Inspection Openings. Inspection openings were made by removing the topping slab concrete, and in some cases the top few inches of structural slab, at eight locations on the west half of the Observation

Deck. The sizes and depth of the inspection openings varied but ranged in depth up to 4 inches. Inspection opening locations are shown in Figure 1-20. The inspection openings coincided with the locations of fourteen concrete cores, OD1 through OD14. At several of these locations, the concrete was chipped away to expose the radial reinforcing to allow for inspection and documentation of the reinforcing and to determine where to place the cores to avoid cutting these reinforcing bars. See Figure 1-21.

The purpose of the inspection openings was to expose the top surface of the structural slab to evaluate whether conditions observed at extracted cores were also present over wider areas of the slab, and to provide a surface conducive to performing nondestructive evaluation of the concrete, as further discussed below.

Nondestructive Testing. Nondestructive test methods used included sounding, impact-echo testing, and ground penetrating radar (GPR). Sounding techniques were used on the structural slab to identify delaminations, voids, and internal flaws in the concrete, which may be associated with freeze thaw damage, delaminations induced by corrosion, or other effects. The investigators used a hammer to gently tap the concrete, as delaminated or unsound concrete sounds hollow when tapped.

The impact-echo method entails introducing mechanical energy in the form of a short pulse into the structure (Figure 1-22). A transducer mounted on the impacted surface of the structure receives the reflected input waves or echoes. Spectral analysis of the reflected compression waves can then be performed to identify flaws and/or deterioration within the concrete, and to measure the thickness of a particular element. The impact-echo method requires access to only one side of the structure.

Ground penetrating radar involves the transmission and reflection of electromagnetic waves into the structure or material (Figure 1-23). The principal of ground penetrating radar is similar to that of pulse echo ultrasonic techniques, except that it uses electromagnetic instead of acoustic waves. A transmitting antenna sends a diverging short pulse of energy, while a receiving antenna collects the energy reflected from interfaces between materials of differing dielectric properties (such as steel reinforcement). Both impact echo and ground penetrating radar techniques have been used to estimate the thickness of concrete members and multi-layer systems, determine the location and cover of reinforcing bars, and identify the locations and dimension of moisture variations, voids, cracking, and delaminations in concrete.

Nondestructive testing using impact-echo and GPR techniques was performed at the inspection openings described above, in an effort to determine whether nondestructive test methods would provide information correlating with that obtained through laboratory examination of concrete cores taken at these locations. The following results were obtained:

At locations corresponding with nine core removals, nondestructive testing indicated that freeze thaw deterioration was present only at the top of the structural slab.

At locations corresponding with three core removals, nondestructive testing indicated that freeze thaw deterioration was present only at the bottom of the slab.

At one location, nondestructive testing indicated the freeze thaw deterioration was present at both the top and bottom of the slab.

Results obtained through nondestructive testing were compared with those obtained through laboratory examination of the concrete cores for freeze thaw deterioration. The following correlations were noted:

At seven of the thirteen core locations for which an assessment was made by nondestructive methods for condition of the concrete at the top of the slab, findings from the nondestructive testing correlated with those of the laboratory study. At six of the thirteen core locations, findings did not correlate.

At one of the four core locations for which an assessment was made by nondestructive methods for condition of the concrete at the bottom of the slab, findings from the nondestructive testing correlated with those of the laboratory study. At three of the four core locations, findings did not correlate.

The nondestructive testing, including sounding, impact echo, and ground penetrating radar, was not found to be effective in evaluating either the extent or depth of freeze thaw deterioration. The applicable methods were not effective where freeze thaw deteriorated concrete was present because the test methods were only able to determine if freeze thaw deterioration was present near the top of the slab, but not below areas where freeze thaw deterioration was present near the surface. In addition, the results obtained from both the nondestructive testing and the petrographic studies indicate that the condition of the concrete is highly variable. Not only is sound and unsound concrete present, but the severity of freeze thaw deterioration varies. This variability results in acoustic readings that are difficult to interpret, as there acoustical differences between sound and unsound concrete are difficult to discern. Thus sounding, as well as the other methods tested, provide results that correlate poorly to actual condition present.

Vertical Cores through Deck Thirty-one concrete cores were made downward from the top of the Observation Deck into the reinforced concrete structure. Adjacent to the locations of cores OD1 through OD7, concrete was chipped out down to the level of the radial reinforcing bar at an area approximately 1'-6" x 0'-6" in plan. These deeper areas were within the area of the inspection openings shown in Figure 1-20. At cores OD8 through OD31, a 6 inch diameter core was made down to the top of the radial steel to locate the smaller diameter core between radial steel bars. Figures 1-24 and 1-25 illustrate examples of the coring and removed cores. The concrete cores were examined petrographically to determine the presence and depth of freeze thaw deterioration. Detailed findings for each core are provided in Appendix B. Four cores were also made through the Observation Deck during the 2006 investigation.

The lengths of the concrete cores ranged from 12 inches to 30 inches. The relationship between the top and bottom of each core and the concrete structure is shown in Figure 1-26. This figure also shows the levels of each core at which freeze thaw deterioration was observed (based on petrographic examination).

The following conditions were noted in the thirty-five cores taken in both phases of the study, as also shown in Figure 1-27:

Twelve cores were found to have freeze thaw deteriorated concrete at a level below the radial steel reinforcing bars.

Twenty-three of the cores were found to have freeze thaw deteriorated concrete only above the radial steel reinforcing bars.

Five of the cores were found not to have freeze thaw deteriorated concrete.

Six of the cores were found to have freeze thaw deteriorated concrete near the bottom of the concrete, well below the radial steel reinforcing bars. The depth of deterioration observed in these cores ranged from 1/2 inch to 3 inches.

A contour plan showing an estimate of the depth and extent of freeze thaw deteriorated concrete for the entire Observation Deck is provided in Figure 1-28. This figure also illustrates the region of the

Observation Deck where freeze thaw deterioration is estimated to extend down to a level below that of the radial steel reinforcing bars.

The extent and depth of freeze thaw deteriorated concrete was found to be greater at the projecting corners of the Observation Deck as compared to areas nearer the Penthouse. This is consistent with areas that would be expected to experience more extreme temperature, more temperature cycles, and more water penetration into the slab due to the slope to drain locations.

Horizontal Cores through Fascia Nineteen cores were made through the exterior granite fascia panels to extract concrete from various locations along the south, east, and west reinforced concrete spandrel beams at the Observation Deck.

Figures 1-29 and 1-30 illustrate examples of coring and removed cores. In addition, four cores through the fascia were made during the 2006 investigation, of which three cores extended into the concrete. (The fourth core, which extended only into the granite and not into the concrete backup, is excluded from the following discussion.) Of the total twenty-two cores taken in both phases of the study, all but one were made in cracked granite fascia panels. Locations of cores taken through the fascia are shown in Figure 1-5 and Figure 1-28. The concrete cores were examined petrographically to determine the presence and depth of freeze thaw deterioration. The detailed findings for each core are provided in Appendix B.

The cores ranged from 16 inches to 28 inches in length, and therefore included concrete from the concealed spandrel beam ranging from 5 to 17 inches in length (excluding 6 inches of granite and 5 inches of concrete between dovetails). Sixteen of the cores were greater than 23 inches in length, indicating that these cores extended through the full thickness of the spandrel beam. The depth of each core relative to the outside face of the fascia panel and the reinforced concrete spandrel beam for each core is shown in Figure 1-31. This figure also shows the levels of each core at which freeze thaw deterioration was observed.

The following conditions were noted in the twenty-two cores taken in both phases of the study, as also shown in Figure 1-32:

Approximately fourteen of the cores were found to have freeze thaw deteriorated concrete that extended through more than half the thickness of the spandrel beam. (The three cores taken during the first phase of the study were not of sufficient depth of concrete to confirm whether freeze thaw deterioration extended significantly into the spandrel beam.)

Four of the cores were found not to have freeze thaw deteriorated concrete.

Although cores were removed at various heights of the spandrel beam, even several cores at higher locations on the spandrel beam exhibited freeze thaw deteriorated concrete. Refer to Figure 1-5 and

Figure 1-32. Figure 1-33 illustrates a section through the spandrel beam and Observation Deck, showing the extent of concrete freeze thaw deterioration based on information obtained from examination of the cores.

The location and extent of freeze thaw deteriorated concrete strongly indicates that, at least along the south, east, and west elevations, freeze thaw deterioration of the reinforced concrete spandrel beams is severe and extensive. It is likely that freeze thaw deteriorated concrete is most severe at and below the level of the structural deck, but freeze thaw deterioration was also noted where the beam projects above the structural slab.

Horizontal Cores from Interior of Shaft Two cores were made from the interior of the shaft to extract concrete from south and west reinforced concrete walls at the level of the Observation Deck slab. The purpose of the cores was to determine if freeze thaw deteriorated concrete was present in the innermost portion of the Observation Deck slab and underneath the concrete walls of the Penthouse. Figure 1-34 shows an example of a core removed from the Penthouse wall. The concrete cores were examined petrographically to determine the presence and depth of freeze thaw deterioration. The detailed findings for each core are provided in Appendix B.

The locations of the cores are shown in Figure 1-28. The length of the core at the south elevation was 25 inches and at the west elevation 28-1/2 inches. The height of both cores was approximately at the level of the radial reinforcing steel of the Observation Deck. Neither of the cores was found to have freeze thaw deteriorated concrete present. Freeze thaw deteriorated concrete was also not observed in cores taken adjacent to the Penthouse walls.

Stabilization Repair After completion of the investigation, the areas of the topping slab that had been removed and all core holes into the structure were filled with concrete. The embedded drain bodies were cleaned out and the area between the drain body and the pipe below was filled with sealant. After final preparation, a new waterproofing membrane was installed on the deck and up the granite walls of the Penthouse and the parapet fascia where the membrane was terminated with a retaining bar. The top of the termination bar was filled with sealant. See Figures 1-35 and 1-36. The membrane was flashed into the four drains and a temporary drain screen was installed in the clamping ring. This waterproofing was designed to be temporary and easily maintained until the long term repairs can be initiated. On top of this membrane a 1-

1/2 inch thick temporary precast concrete paver system was installed on insulation board pedestals. See

Figures 1-37 and 1-38. The open joints of this system allow water to be shed off the pavers and onto the waterproofing membrane and to the four drains quickly. This paving system can be easily maintained and allows for ready inspection of the waterproofing system.

Penthouse

Observations at Roof During preparation for stabilization repairs to the roofs of the Penthouse, it was determined that the lower roof over the Penthouse was not repairable (Figure 1-39 and Figure 1-40). Therefore, a longer term solution was proposed. Closer inspection of the roof beneath the Lantern revealed that the 3 inch thick concrete deck, which includes glass prisms (originally used to provide light to the elevator equipment area within the penthouse), was deteriorated and will require repair or replacement before a long term roofing membrane repair can be implemented. The underside of the slab was revealed by removed insulation board that had been installed against the slab on the interior. Corroded reinforcing was observed at areas of spalled concrete (Figure 1-41). In addition, cracking of many of the glass prisms was observed.

During this inspection, the sheet metal enclosures of two of the Lantern “feet” were opened and the steel structure within was examined. Corrosion of the angles supporting the Lantern was observed. See Figure

1-42 and Figure 1-43. The reinforced concrete wall supporting this roof area and the concrete cross beams are also deteriorated.

Repairs to Penthouse Wall and Roof Because the joints in the Penthouse walls had been filled with sealant in the past, the existing mortar has not bonded to the stone and most of the joints were open, allowing water to penetrate the Penthouse structure. The temporary repairs included removal of all old mortar and sealant, and repointing with Dow

790 silicone sealant in an attempt to limit water penetration into the structure. See Figure 1-44. Dow 790 silicone sealant had been used to seal joints between granite panels during repairs made in 1983.

At the flat roof areas above the Penthouse, complete removal and replacement of the membrane and flashing was completed because the existing roofing was deteriorated and at the end of its service life, and would have been difficult to repair, even on a temporary basis. The work included removal of the roofing system and the installation of a new roofing system, including new flashings at the inside and outside perimeter of the roof. See Figures 1-45 through 1-48.

Because of the poor condition of the concrete structure of the roof area beneath the Lantern and the need to address the steel structure of the Lantern, temporary patching was completed to this small roof area by covering all seams and flashing and replacing all sealant. Due to the poor condition of this roof, the effectiveness of these repairs is only temporary and the repairs should be monitored and replaced periodically. See Figure 1-49.

Upper Plaza Structure

A visual survey and sounding of the concrete structure were performed at approximately one quadrant of the Upper Plaza to evaluate the current condition of the reinforced concrete structure. A smaller area at the northeast corner of the Upper Plaza was also surveyed. The area selected for load testing was within the southwest area of the inspection. In addition, three cores were removed for examination for freeze thaw deterioration. One of these cores was tested for compressive strength. Observations from this survey are illustrated in Figure 1-50. Notable conditions observed included concrete deterioration in the form of cracked, spalled, and delaminated concrete. Some areas of concrete sounded “dead” or hollow when tapped with a hammer, indicating delaminations, freeze thaw deterioration, or other defects. In areas of spalled concrete, reinforcing steel was observed with corrosion but not significant loss of cross-sectional area. Areas of previously installed patches were noted. Sound testing of the repairs indicated that some areas may be delaminated and/or debonded. Evidence of water leakage through the deck structure in the form of water staining and efflorescence (mineral deposits) was observed on the underside of the structural slab. Although visual evidence of severe freeze thaw deterioration was not observed at all areas of the slab, beams, and girders, visible freeze thaw deterioration was extensive. Somewhat less water staining and deterioration of the concrete was observed in the dropped slab areas of the plaza that support the planters.

Figure 1-1. Swing stages were used to access the fascia and soffits during the investigation and stabilization.

Figure 1-2. The granite fascia panel at the north end of the west side was damaged by lightning in the

1920s and was pinned to the concrete. Additional displacement was observed and additional stainless steel anchors were added to stabilize the granite.

Figure 1-3. Ten of the thirteen granite fascia panels on the west elevation are cracked.

Figure 1-4. A closeup of the cracked granite fascia panels on the south elevation near the piece that fell. Temporary straps were used while the fascia pieces were stabilized with stainless steel pins and straps.

Figure 1-5. The east, south, and west granite fascia elevations were investigated and the cracking and displacement recorded.

Figure 1-6. Examples of stainless steel straps used to stabilize some of the fascia panels.

Figure 1-7. Where a portion of the granite fascia fell from the south elevation, a marine plywood enclosure was installed to cover the hole and stabilize the fascia.

Figure 1-8. Three granite fascia panels on the east, three panels on the south and five panels on the west were stabilized with stainless steel pins and plates. In addition, at many locations stainless steel straps were used to stabilize the cracked granite.

Figure 1-9. Deflection of the granite soffit panels at the southwest corner was measured at about 3 inches from its original position.

Figure 1-10. A view of the southwest granite soffit. Note that the granite plugs are displaced and appear to be loose.

Figure 1-11. Aluminum beams were used to provide support to cracked portions of the granite soffit panels at the southwest and southeast corners. These beams were attached by stainless steel rods to beams resting on the parapet wall above.

Figure 1-12. The beams to provide support for the granite soffit panels at the southwest and southeast corners were installed from swing stages.

Figure 1-13. The beam underneath the southwest corner was positioned to support cracked portions of the granite, but also partially support one of the loose granite plugs that were installed with the through slab anchors installed in the 1980s.

Figure 1-14. A view of the installed beam underneath the southwest corner soffit.

Figure 1-15. A granite panel on the inside of the parapet was removed to expose the coal tar pitch covered concrete structural beam.

Figure 1-16. The mortar behind the granite parapet panel was severely deteriorated and could be easily removed by hand.

Figure 1-17. Elevations of various elements at Observation Deck. Observations made at the time of core removal.

Figure 1-18. After the granite paving and mortar have been removed the surface drain and pipe are exposed. There was no weeps at the interface between this pipe and the waterproofing membrane.

Figure 1-19. The outer ring is the drain body cast into the topping slab. Within this drain body is the end or hub of the pipe projecting out of the concrete structure. Water can get into the structure between the pipe and the drain body.

Figure 1-20. Plan of the Observation Deck identifying the location of the cores made into the structural concrete both vertically (OD) and horizontally (EF, SF, WF, and PW). In addition, inspection openings in the topping slab to expose the top of the structural slab are outlined in red.

Figure 1-21. In several areas the structural concrete was chipped away to expose the radial reinforcing bars. This inspection opening is close to the west parapet wall where the granite panel was removed.

Figure 1-22. Impact echo equipment was used in an attempt to characterize the condition of the concrete between concrete cores.

Figure 1-23. Ground-penetrating radar equipment was used to locate steel reinforcing and also as an attempt to characterize the condition of the concrete between cores.

Figure 1-24. Cores were taken into the structural concrete at the

Observation Deck in to determine the extent of deterioration of the concrete.

Figure 1-25. Each two inch core was removed and recorded before being bagged and sent to the laboratory for petrographic examination.

Figure 1-26. This chart illustrates the relative location and extent of freeze thaw damage of the vertical cores into the Observation Deck. The cores are organized by location. Note that the northeast cores are higher than the southwest cores. This is because the original structural deck sloped from northeast to southwest to facilitate drainage to the sole drain at the southwest corner.

Figure 1-27. This chart tabulates the location and characteristics of the cores taken and NDT results at the Observation Deck.

Figure 1-28. Plan view (with adjacent fascia elevations) at Observation Deck, illustrating the estimated relative freeze thaw deterioration at the Observation Deck. As expected, freeze thaw deterioration is most severe at the corners of the Observation Deck where it overhangs the column beneath and where there is greater exposure. (Red line shows section drawn in Figure 1-33.)

Figure 1-29. Nineteen cores were taken through the granite fascia and into the structural concrete on the east, south and west elevations.

Figure 1-30. Some of the cores such as this core from the east elevation were obviously freeze thaw damaged and came out in pieces.

Figure 1-31. This chart illustrates the relative depth of the horizontal cores taken through the fascia and the extent of freeze thaw deterioration.

Figure 1-32. This chart numerically tabulates the results of the freeze thaw distress observed in cores removed from the fascia.

Figure 1-33. Drawing of representative section through the spandrel beam and Observation Deck, showing extent of concrete freeze thaw deterioration indicated by…