Friday, May 8, 2015

IN THE "DID YOU KNOW?" CATEGORY, LESSER KNOWN STRUCTURAL ENGINEERING FACTS!

Did you know that high-rise building floor beams are deliberately designed weaker, so that in case of a failure of the column-beam connection, the beam will fail and not the column? This is important because a structure can function with a failed floor beam, but cannot with a failed vertical column.

Did you know that the so called, and dangerous, soft story buildings were designed properly prior to 1972? That is because the building code prior to 1972 allowed a so called "torsional analysis" design method, but, later it was realized that the horizontal torsions of flexible diaphragms created an excessive horizontal deflection and buildings were not designed for that. That's when they changed the code.

Did you know that structural engineers are born scapegoats? That’s because, if they design a building economically, to cost the least amount of money, then the building is not structurally safe enough and therefore not good. But if they design a building to be structurally very safe and sturdy, then the cost of construction will be too expensive, and therefore not good. That's what we call a "no win" or "catch 22" situation.

Did you know you can tell the difference between a very dangerous, un-reinforced brick building from a much safer, more modern reinforced brick building without breaking the walls down? From the outside, brick buildings look very much alike. But when you go closer and you see that the running bond bricks are interrupted every 6 to 7 rows with a layer of brick, laid across the wall, therefore showing only the short side of the brick, you'll know this is an un-reinforced brick building. Why? Brick walls are built as double walls to allow for the necessary thickness, an interior and an exterior wall next to each other separated with mortar only. The higher you go it is more likely that these walls will separate. To avoid this, masons reversed every 6-7th row of brick across the wall to keep the two walls together. Interesting, isn't it?

Did you know that The Richter magnitude scale (also Richter scale) assigns a magnitude number to quantify the energy released by an earthquake? The Richter scale is a base-10 logarithmic scale; therefore, an earthquake that registers 5.0 on the Richter scale has shaking amplitude 10 times that of an earthquake that registered 4.0. (For those not to familiar with mathematics base-10 log 1,000 = 3 base-10 log 10,000 = 4 and base-10 log 100,000 = 5.) You can see that 5 on the Richter scale is 10x more than 4 on the Richter scale.

Now you know.