STRAIN-RATE SENSITIVITY OF STEEL MEMBERS IN SEISMIC RESISTANT BUILDINGS

It is largely demonstrated that strain-rate can influence the material properties of steel members in near-source earthquakes. In the Kobe and Northridge earthquakes anomalous and unexpected collapses were observed in steel structures. Overstrength related to medium strain-rate can lead to larger accelerations, which might result into larger seismic forces as well as in unexpected distributions of internal forces. Both effects might have consequences in seismic design, because they correspond to a wrong estimation of the force reduction factor and undermine the whole concept of capacity design. Especially in joints, in zones thermally affected by welding and in strain concentration areas, unexpected failure modes were observed. The presence of material defects has also been reported as an additional source of effects related to strain-rate. Moreover, strain-rate sensitivity is a thermally activated problem; therefore temperature sensitivity must be kept into account (embrittlement and overstrength due to low temperature). All these phenomena have been reported along with their potential for brittle failures and dramatic reduction of available ductility.

PERONI Marco;  NEGRO Paolo;  SOLOMOS George; 

2014-08-19

Editura orizonturi universitare

JRC86208

978-973-638-552-0,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC86208,