STRUCTURAL FAILURES AND COLLAPSES Toni Kekki / NKUAS

ENGINEERING IN GENERAL Toni Kekki / NKUAS Solving problems Solving problems with sufficient safety according to loads and stresses, and this all has to be economically and environmentally sustainable

ENGINEERING IN GENERAL Toni Kekki / NKUAS safety cost Safety factor = 1.0 Safety according to national regulation (Unnecesserary) extra cost Unaccep- table zone Danger zone

Safety Investigation Authority Toni Kekki / NKUAS

Safety Investigation Authority Toni Kekki / NKUAS Mandatory authority for international regulations on airborne, maritime and railroad transportation Building investigation is mandated by Finnish government without international regulation SIA works under Ministy of Justice as an independent authority. Funding comes from government.

LAST FEW YEARS IN FINLAND... Toni Kekki / NKUAS On winter 2009 – 2010 we had 99 registered roof collapses or structural failures with risk to life. On winter same count was 117! This winter count is so far 22. Average was 62 / year  Absolutely unacceptable!

Toni Kekki / NKUAS Not nearly enough snowload to cause failure

Toni Kekki / NKUAS The most stressed joints were not calculated at all. Truss-analogy and hand-method calculations were totally deficient. Designer was experienced steelstructure expert! Section of a structure.

Toni Kekki / NKUAS

Trusses without proper buckling support

Toni Kekki / NKUAS

Conditions too moist for plywood; not how it was designed. Connection to foundation was rotten; concrete was poured around wood without isolative material

WHAT CAUSES FAILURES Toni Kekki / NKUAS

WHAT CAUSES FAILURES Toni Kekki / NKUAS

CASE: Industrial facility in North-Karelia Part of a roof collapsed suddenly and without pre-warning Personal injuries were avoided. Interruption of a production and machinery damages caused losses in income. Construction was made in New enlargement was made in In this project roof shape was modified.

Toni Kekki / NKUAS CASE: Industrial facility in North-Karelia

Toni Kekki / NKUAS

CASE: Industrial facility in North-Karelia

Toni Kekki / NKUAS CASE: Industrial facility in North-Karelia

Toni Kekki / NKUAS CASE: Industrial facility in North-Karelia PartForce (kN)Original force (kN) Chance in % P9-43,26-33,38130 P7-48,71-28,41172 D8+4,61+0,76607 D9+18,23+10,15180 D10-30,75-28,42108 P12+35,53+30,48117 P13+25,18+21,99115 V4-10,53-3,61292

THINGS TO REMEMBER: Toni Kekki / NKUAS Collapses don’t just happen. They have usually logical explanation and, sad but true, chain of events. Computer is a good employee but really bad boss! User is the boss and always responsible of results  make necessary checkings!!! Design and install all structures so well that you and your family could walk underneath this structure.

SOME LINKS TO FOLLOW Toni Kekki / NKUAS Animation about sinking of Estonia-ferry: Pulp silo baseplate failure (insufficient piling) National Geographic: Seconds from disaster Skywalk: Hotel New World: Korea department store:

Toni Kekki / NKUAS ”The important thing is not to stop questioning. Curiosity has its own reason for existing” -Albert Einstein-