Albemarle County Courthouse

WDP performed a field investigation at the Albemarle County Courthouse to evaluate potential causes for cracking and sagging in the reinforced concrete floor slabs and to verify if they were indicative of potentially unsafe conditions. WDP’s investigation included visual and tactile surveys at the slabs to verify the extents of the cracking, observe the floor construction, and to document the extents of corrosion, sagging, and other deficiencies. WDP surveyed the floors using surface-penetrating radar (SPR) to verify the location and orientation of reinforcement and other embedded items within the slabs. The thicknesses and dimensions of the various structural elements were recorded for subsequent analysis.

Description

WDP installed short and long-term cracking monitoring devices to measure active movement of the slab and to verify whether additional sources were contributing to the cracking, or the cracking was stable. The short-term monitoring was performed electronically at close intervals during a period of a couple weeks using linear variable differential transformers (LVDTs). This was done while the building was occupied to verify if the crack widths are affected by occupant loads or diurnal temperature fluctuations.

WDP compared the field-collected data with historic references to evaluate the construction methods and materials used in the original construction. WDP performed a structural analysis of the slab sections and supporting steel trusses using the geometric information obtained during the investigation and historic material references to verify the adequacy of the slabs for occupant loads. WDP analyzed the LVDT data and found that the observed movement is most likely related to thermal expansion and contraction of the concrete floor slab resulting from changes in the ambient internal temperature.

Challenges/Solutions

Scope of Services