Q: How do beam deformation patterns indicate fire origin?
A: Web buckling direction reveals temperature gradients. Oxidation color gradients map thermal progression. Spalling patterns identify hydrocarbon accelerants. Residual stress measurements determine maximum temperatures. Distortion vectors point to collapse initiation zones.
Q: What metallurgical analysis determines fire duration?
A: Decarburization depth measurements via microhardness. Grain growth analysis using electron backscatter diffraction. Phase transformation quantification through XRD. Oxide layer thickness correlation with ISO 834 curves. Microstructural damage classification per ASTM E1188.
Q: How is electrical arc damage distinguished from fire effects?
A: Bead formation patterns at connection points. Unique spatter geometries from molten metal expulsion. Localized hardening exceeding fire-affected zones. Carbon deposition analysis around arc points. Circuit failure sequence reconstruction.
Q: What techniques identify chemical accelerants?
A: GC-MS analysis of absorbed residues in mill scale. Laser-induced breakdown spectroscopy mapping. Micro-extraction from corrosion products. Comparative analysis of oxide layer chemistry. Charred material adhesion patterns.
Q: How do beams provide structural collapse sequence evidence?
A: Plastic hinge formation sequence mapping. Connection failure fracture surface analysis. Torsional deformation indicating asymmetric loading. Impact damage patterns from falling debris. Residual strain measurements using neutron diffraction.
