Structural Evaluation of McClung Bldg 4 and 5 Following the February 1, 2014 Fire 500 West Jackson Avenue Knoxville, TN.

Transcription

1 Structural Evaluation of McClung Bldg 4 and 5 Following the February 1, 2014 Fire 500 West Jackson Avenue Knoxville, TN Prepared By: National Resource Management, LLC Carl Oaks, P.E. Jack Thomison, P.E. February 5, 2014 NRM-LLC, PO Box 23858, Knoxville, TN PH: , FAX

2 1.0 Background National Resource Management, LLC (NRM) was requested by KCDC to perform a structural evaluation of the buildings located at Jackson Avenue, Knoxville, TN on February 4, 2014 following a fire that occurred on February 1, The buildings were inspected by structural engineers, Mr. Carl Oaks, P.E. and Mr. Jack Thomison P.E. Prior to this, NRM inspected the building following a previous fire on February 7, NRM made another follow-up inspection and provided a detailed report on June 8, This fire destroyed building 5 and also damaged the building 4 roof and upper (6 th ) floor. The scope of this assessment was: 1. Determine if entry into the remaining shell of building 5 was safe for fire investigators. 2. Determine if it would be safe to reopen Jackson Avenue for public access. 3. Determine if it would be safe to allow the businesses and residences on the south side of the street to reopen. 2.0 Inspection The damaged buildings were surveyed at 9:00 am on February 4, The site was viewed from the Jackson Avenue level and from the KFD ladder truck above and to the south of the site. The remains of building 5 were inspected from above from several angles. The roof of building 4 was inspected from above and through the south side windows that were opened to allow inspection of the interior of the 6 th, 5 th, and 4 th floors. 3.0 Findings The interior of building 5 was found to be completely destroyed by the fire. The south wall below the street level had fallen to the inside of the building. The west wall was seen to be still partially standing about 10 feet above street level and about 30 feet above the rail yard grade. The wall above had fallen to the interior of the building. The north wall was also partially standing with some parts on the east side extending up to the 4 th floor level, about 50 feet above rail yard grade. Some parts in the center were only about 20 feet above the rail yard grade. The northwest corner of the north wall was leaning and was very unstable along with the unsupported sides of the window openings. The east wall was still fully intact and standing up to the roof level, about 70 feet above rail yard grade. The chimney attached to the east wall was also fully intact and extended up about an additional 20 feet. The chimney was leaning toward the west and had moved away from the adjacent building 4 walls by several inches. The center of the building 5 east wall was bowing west toward the building interior. Building 4 was found to be still fully standing with no obvious damage to the walls inspected and no structural connections to the adjacent building 5. There were signs of extensive burning on the roof with several areas where the roof was open and significant charring and complete failure was seen on some of the underlying roof beams. The worst damage to the roof appeared to be on the north end where most of it appeared to be burned-through and open; however, one area of burn-through was about 10 feet from the south end in the east-west center. The 6 th floor level had large amounts of charred and water soaked debris on the floor. Daylight could be seen coming through the extensive roof openings. Major charring was seen on the central girders and the remaining roof beams. Several beams had fallen down to the floor. Other beams were McClung Fire Damage Inspection 2/4/2014 Page 1

3 seen with compromised seats and bowing at the center of beams that had fire damage that appeared to be close to failure. In addition, several large (6 8 dia.) sprinkler header pipes were fallen down to the floor. No fire damage was seen on the 5 th, 4 th, or 3 rd floor levels. They all appeared to have no obvious changes from the last inspection in 2012 and damage from water intrusion was still apparent. The interior of building 5 was found to be completely destroyed by the fire. McClung Fire Damage Inspection 2/4/2014 Page 2

4 The south wall of building 5 below the street level had fallen to the inside of the building. The west wall was seen to be still partially standing about 10 feet above street level and about 30 feet above the rail yard grade. The wall above had fallen to the interior of the building. The north wall of building 5 was also partially standing with some parts on the east side extending up to the 4 th floor level, about 50 feet above rail yard grade. Some parts in the center were only about 20 feet above the rail yard grade. The northwest corner of the north wall was leaning and was very unstable along with the McClung Fire Damage Inspection 2/4/2014 Page 3

5 unsupported sides of the window openings. The east wall of building 5 was still fully intact and standing up to the roof level, about 70 feet above rail yard grade. The chimney attached to the east wall was also fully intact and extended up about an additional 20 feet. McClung Fire Damage Inspection 2/4/2014 Page 4

6 McClung Fire Damage Inspection 2/4/2014 Page 5

7 The building 5 chimney was leaning toward the west and had moved away from the adjacent building 4 walls by several inches. The center of the building 5 east wall was bowing west toward the building interior. There were signs of extensive burning on the building 4 roof with several areas where the roof was open and significant charring. McClung Fire Damage Inspection 2/4/2014 Page 6

8 The worst damage to the building 4 roof appeared to be on the north end where most of it appeared to be burned-through and open; however, one area of burn-through was about 10 feet from the south end in the east-west center. McClung Fire Damage Inspection 2/4/2014 Page 7

9 The building 4 6 th floor level had large amounts of charred and water soaked debris on the floor. Daylight could be seen coming through the extensive roof openings. Several beams had fallen down to the floor. In addition, several large (6 8 dia.) sprinkler header pipes were fallen down to the floor. A few beams, such as the fourth beam from the front in the above photo had significant deflection in the center of the beam and appeared close to collapse. McClung Fire Damage Inspection 2/4/2014 Page 8

10 Major charring was seen on the building 4 6 th floor level central girders and the remaining roof beams. Other beams were seen with compromised seats that appeared close to failure. No fire damage was seen on the 5 th floor level. It appeared to have no obvious changes from the last McClung Fire Damage Inspection 2/4/2014 Page 9

11 inspection in 2012 and damage from water intrusion was still apparent. No fire damage was seen on the 4 th floor level. It appeared to have no obvious changes from the last inspection in 2012 and damage from water intrusion was still apparent. McClung Fire Damage Inspection 2/4/2014 Page 10

12 No fire damage was seen on the 3 rd floor level. It appeared to have no obvious changes from the last inspection in 2012 and damage from water intrusion was still apparent. McClung Fire Damage Inspection 2/4/2014 Page 11

13 4.0 Conclusion Building 5 The remaining structures on building 5 are very unstable. Of primary concern are the east wall and the attached chimney. The chimney is clearly leaning inward and the center of the wall is also bowing toward the building interior. The north wall is very unstable with several unconnected window openings. The west wall is also unsupported and, particularly, the north end has a section leaning precariously toward the building interior. Building 4 Based upon the extent of the water soaked debris that has fallen from the roof level onto the sixth floor it is experiencing heavy loading. The roof beams that appeared to be close to collapse due to fire damage could cause the sixth floor to experience even heavier loading. Additionally, previous examinations and reports have indicated that the beams and girders, particularly in the top levels of the structure have been exposed to moisture deterioration for many years. This has caused rot in the top several inches of many of the beams and has weakened their ability to carry loads. Also there has to be a consideration for impact loads if the roof or upper floors collapse. The 2007 report showed areas of the sixth floor that experienced water damage and rot as well as the fifth floor showed an area of standing water and in one area the floor had rotted completely through. The 2012 inspection showed that no actions had been taken to stop the water intrusion and significant deterioration had occurred since the 2007 inspection. There is a potential for further roof failure that could in-turn cause increased loading on the floor below with a possibility that it may fail and cause a cascading effect on the lower floors. The N-S girders and the E-W beams provide lateral stability to the outer unreinforced masonry brick walls. If a cascading structural failure were to occur, it could destabilize the walls and possibly cause a complete building collapse. 5.0 Recommendations 1. Due to the unstable and leaning remaining structures it is not recommended that entry be made into the remaining shell of building 5 by fire investigators or anyone until those dangers are removed. 2. Due to the severely compromised roof on building 4 and the potential of increased loading on the floor below, the possibility of a cascading floor failure that could destabilize the walls leading to complete building collapse cannot be ruled out. For that reason it is not recommended to reopen Jackson Avenue for public access until building 4 is stabilized or demolished. 3. Since the possibility of complete building collapse as described above cannot be ruled out, it is not recommended to allow the businesses and residences on the south side of the street to reopen until building 4 is stabilized or demolished. McClung Fire Damage Inspection 2/4/2014 Page 12