THOUGHTS ON STRUCTURAL ENGINEERING PRACTICE Presentation atUniversity of Texas and Purdue University November 2008 UUR ERSOY Bogazici University, Civil Engineering Dept. Istanbul - Turkey The Mausoleum at Halicarnassus The Temple of Artemis Bozdogan Aqueduct (370 A.D.) Longest Waterline = 240 km, 149 mi From Stranca Mountains to stanbul St Sophia, stanbulSt Sophia, stanbul Selimiye Mosque Edirne CIVIL ENGINEERING PRIOR TO 18 th CENTURY: ARCHITECTURAL AND CIVIL ENGINEERING WORKS WERE DONE BY THE SAME CRAFTSMEN. I WOULD CALL THEM : MASTERS OR BUILDERS MAIN TOOLS USED BY EARLY BUILDERS: -PAST EXPERIENCE -THEIR OWN EXPERIENCE -ENGINEERING INTUITION TECHNOLOGY (From Greek) TECHNE = ART, CRAFT LOGOS = SCIENCE SOMEONE HAS SAID THAT THE THEORY OF STRUCTURAL DESIGN IS BUILT BY ATTRIBUTING IMPOSSIBLE PROPERTIES TO NON-EXISTENT MATERIALS !!! Hardy Cross HISTORY OF SCIENCE IS FULL OF BEAUTIFUL THEORIES, BUTCHERED BY SMALL UGLY FACTS ! Sir S. Thomas TENSILE STRENGTH OF CONCRETE: f ct = 4 (f c ) 0.5 (In British units) TO EXPRESS THIS EQUATION IN SI UNITS, DIVIDE THE CONSTANT BY THE SQUARE ROOT OF /(142) 0.5 = EQUATION EXPRESSING THE TENSILE STRENGTH AS A FUNCTION OF COMPRESSIVE STRENGTH BECOMES, f ct = (f c ) 0.5 !!!!!!! ( SI units) THE GREAT TRUTHS OF ENGINEERING ARE SIMPLE... AN ENDLESSLY COMPLEX PRESENTATION OF AN ENGINEERING FACT INDICATES COMPLICATION IN THE BRAIN OF THE PROPOUNDER RATHER THAN COMPLEXITY OF NATURE. Hardy Cross Building Model ANALYSS FILTER DECISION THE ASSEMLY CAN NEVER REPLACE THE BRAIN THAT HAS CREATED IT ! MACHINES,METHODS AND SYSTEMS CANNOT BE A SUBSTITUTE FOR MEN Hardy Cross METHODS OF ANALYSIS ARE OFTEN VERY FORMALISTIC, LIKE A SAUSAGE GRINDER. IF CERTAIN NUMERICAL DATA ARE FED INTO ONE END OF THE ANALYSIS AND A CRANK IS TURNED, A LOT OF LITTLE SAUSAGES (moments, shears, deformation etc.) COME INEVITABLY OUT OF THE OTHER END OF THE MACHINE. IT WORKS QUITE SMOOTHLY; IN FACT IT WORKS WITH DECEIVING SMOOTHNESS. BECAUSE THE SAUSAGES SEEM UNIFORM AND REGULAR, IT IS OFTEN ASSUMED THAT THE MEAT CAN NOT BE SPOILED. Hardy Cross IT IS IMPORTANT TO KNOW THE LIMITATIONS OF KNOWLEDGE AND ASK QUESTIONS, SIMPLE QUESTIONS, THAT MAY OPEN UP HOLES THROUGH WHICH LIGHT CAN FILTER INTO OUR DARK ROOMS. Hardy Cross PLASTIC HINGE: ELASTO-PLASTIC BEHAVIOUR ROTATION UNDER CONSTANT MOMENT M p M p = SECTION CAPACITY M d, depends on M r (Revised) (Linear Analysis) IF Yielding in column 1 Elastic Analysis o1 o1o1 T o2 1 Wrong detailing Better detailing