Structural Condition
Foundation The structure is founded on a perimeter concrete stem wall that encloses a crawlspace and extends above grade by several feet. The exterior face of the concrete stem wall is coated with gray paint. Given the age of the structure it is likely the stem wall bears on a continuous concrete footing (although this is unknown since there are no available original structural drawing and no excavation was included as part of this scope). On the interior of the structure's crawlspace, four tapered concrete pedestals support the floor framing of the stage. At the southern or front end of the structure, two concrete buttresses support the southernmost roof arch. Overall, the building foundations appear to be in good condition based on the overall system performance. There is one vertical crack in the east foundation wall which is likely a naturally-formed expansion joint. The west foundation wall is covered in ivy, which can be detrimental to the structure over time. Relatively regularly spaced vertical cracks occur in the in foundation wall along the front of the stage that are likely naturally-formed expansion joints. The concrete buttresses on both sides of the largest arch have horizontal cracks at the same height. These are likely cold joints from the original concrete pour during construction. Both the vertical expansion joint cracks and horizontal cracks at the cold joints are not of structural concern. Visible from the crawlspace under the stage, there is a large vertical crack in the 6" thick concrete foundation wall located under the wall at the back of the stage. The crack is located at the center of the stage and is 3/4" wide at the base and 2" wide at the top. Based on photographs taken in 2014 compared to those taken in 2021, the movement does not appear to be active as the crack widths appear to not have changed. This crack is caused by settlement of the east side of the foundation wall. There is no other stark evidence of this movement in the structure above indicating that the redundant wood roof/wall framing is distributing the changes in the load well. Overall, this crack is not of major structural concern. However, it is in the best interest of the resource to monitor the crack and stitch it together to provide continuity at the foundation wall. Roof Framing The roof structure contains five equally spaced three-point, glulam wood arches that decrease in size from the front (south) to the back (north) of the Bandshell. The roof framing was not exposed during these site observations; however previous reports describe a hinged connection at the top of each arch and a tie rod within the depth of the stage framing that ties the bottoms of each arch together. Based on photographs from the 1996 renovation of the roof framing, 2x vertical lumber struts support the roof sheathing and 2x horizontal lumber extends between the glulam trusses to brace the structure. The wood arches bear on steel saddles anchored to the concrete foundation wall.
Figure 1-24. Vertical foundation crack on the east side, 2020 (source: Ratio and JVA)
Figure 1-25. Renovation of the Bandshell framing, 1996 (source: City of Boulder)
2-22
Glen Huntington Bandshell
Made with FlippingBook Ebook Creator