Laser scans enable rapid, accurate verification of field conditions in structural evaluations.
Data collected through the laser scan process can be used to verify existing conditions and to obtain detailed measurements over large areas that would otherwise be impractical to capture. When applied to buildings with exposed structural members, this information can be used to more fully describe and represent the current performance of the structure. Post-processing of the point cloud can also call attention to problems that may not be apparent from a visual investigation only.
As part of a thorough structural investigation of an existing building that appeared to be experiencing severe deflections of long span elements, Odeh Engineers paired laser scan data with a structural, finite element analysis model. By capturing elevation information within the entire area in question, the point cloud was used to verify the deflected shape predicted by the structural analysis model and confirm predictions of the long term behavior of the structure. While traditional survey methods would have allowed for specific control points throughout the structure, the detailed existing condition map generated from the laser scan would not have been practical.
Laser scans were used to supplement visual investigation of an expansive mill building in northeastern Massachusetts showing signs of substantial deflections of the bottom chord bearing attic floor structure. Scan data was collected within the attic as well as from the floor below where the truss bottom chords had been left exposed. Data from the two perspectives of the attic floors was then combined and the relative floor deflections mapped.
In addition to the observed floor deflections, several attic trusses exhibited signs of lateral movement at the connection the masonry bearing walls below. Many of the vertical steel members also appeared to have been bent over time. Analysis of the point cloud showed that most of the existing roof trusses were racking significantly in one direction.