Exceptional Loadings / Robustness June 14, 2002 Volos A.M. (Nol) Gresnigt Delft University of Technology The Netherlands

Exceptional loadings / actions (1) Explosion - where: –Buildings: gas explosion - limit damage –Refinery : explosion - blast to control buildings –Offshore platforms: gas - living quarters –Transport: road / ship / pipeline –Fireworks (Enschede 2000) Explosion - research: –Safety and reliability analyses to quantify acceptable risk –Identify possibilities to avoid occurrence and evaluate effectiveness and costs of such measures –Design guidelines to limit damage - “ALARA principle”

Exceptional loadings / actions (2) Fire –Development to natural fire concept –Laws and building regulations - practice - local authorities –Optimisation fire safety / protection measures –Research at TNO - TUD Collision –Buildings / bridges / offshore platforms / …. –Identify possibilities to avoid occurrence and evaluate Earthquake –In 1992 one exceptional with Richter 5.8 near Roermond –July 22, 2002 one with 4.9 in the same area –Faults in earth crest - mining (coal-gas) –Design: wind load is supposed to be adequate

Robustness (1) Strength - rotation / deformation capacity –Work of Martin Steenhuis: interaction to structural reliability –Work of P. Zoetemeijer –Various studies in connection with explosion safety / design –…... Practical application in engineering community ? –Design guides –Education: much has to be done…...

Robustness (2) Education –Design philosophy Loads and deformation requirements often not quantified in standards Many loads and imposed deformations not taken into account Robustness - deformation capacity needed: not quantified Schematisation of the structure in the structural analysis (e.g. hinges / stiff connections) –Practical Welded connections: sufficient strong welds and ductile weld metals Bolted connections: sufficient strong and ductile bolts Yielding in the plate material before failure of welds / bolts Bearing above shear T-sub yielding of the plates above rupture of the bolts …...

Robustness (3) Education –In practice Steel construction shop has to design the connections Designer of connections often not well skilled Designer of connections often not well payed Tendency to simplify connections design and above all simplify connection calculations –Examples of poor design / calculations Thick end plates that never yield; then determine number of bolts on the basis of design load: no check on deformation capacity etc. Lap joints: relatively thick plates and thin bolts: no need for checking bearing, just shear from table to determine number of bolts Semi-rigid calculation and verification on one half A4……..

Concluding Theoretical and experimental research must go on Education and checking of people in practice is essential Task of local building authorities Political awareness and involvement will improve, especially after some collapses and disasters in recent years