Basic Static

  Dead load Volume of beam 10.0 x 0.6 x 0.3 = 1.8 m 3 Unit weight of reinforced concrete = 24 kN/m 3 Therefore, dead load of beam = volume x unit weight = 1.8 m 3  x 24 kN/m 3 = 43.2 kN Dead load on a structure is the result of the weight of the permanent components such as beams, floor slabs, columns and walls. These components will produce the same constant 'dead' load during the lifespan of the building. Dead loads are exerted in the vertical plane. Dead load = volume of member x unit weight of materials By calculating the volume of each member and multiplying by the unit weight of the materials from which it is composed, an accurate dead load can be determined for each component. The different components can then be added together to determine the dead load for the entire structure. Material Unit weight kN/m 3 Plain concrete 23.5 Reinforced concrete 24 Glass 25.5 Mild steel 77 Hardwood 11 Softwood 8 Table 1: Dead load comparisons of various materials The Orginal Link:  http

Trusses: An Angle on Stress During Earthquake                                   the picture is taken to show the deformation Objectives/Goals  The intent of this project is to examine whether different angles change the strength of a truss during an earthquake. The hypothesis is that trusses formed of 60º angles will last the longest during a simulated earthquake.  Methods/Materials  The materials used in this project are as follows; an earthquake simulator and enough wood to build 60 trusses(I used 3mm by 3mm wood.) You will also need super-glue, corkboard and wax paper for making the trusses. Pins are very helpful for holding the joints together while the glue dries. A stopwatch/timer is also needed to time how long a truss lasts. A table saw capable of cutting at various angles is also needed. The testing procedure begins, after manufacturing the actual trusses, with placing a truss on the P-wave simulator. The simulator is then activated. Once the simulator is activated, a timer i

  What is the best angle for a truss bridge? Design engineers normally try to keep it at 45° as it is the best compromise. There are advantages in having a steeper angle for the diagonal members and also disadvantages. Greater depths with lesser number of panels and steeper angles result in lesser chord forces. But that also results in increase in the number of panels and consequently more diagonal members and and also vertical members, thus increasing amount of fabrication work. If the depth of the truss is decided and frozen from functional or architectural or other considerations, and if you try to increase the width of the panels to reduce their numbers then the angle will be very shallow and the axial forces in the diagonal members will increase. The truss will also deflect a little more. Deciding the optimum panel widths, the optimum truss depths and the optimum angles for the diagonals is a skilled trial and error task for the designer. Most designers start with 45° and then fin

The Elements Of Bridge Design Basic forms There are six basic bridge forms: the beam, the  truss , the arch, the suspension, the  cantilever , and the cable-stay.   Beam The  beam bridge  is the most common bridge form. A  beam  carries vertical loads by bending. As the beam bridge bends, it undergoes horizontal compression on the top. At the same time, the bottom of the beam is subjected to horizontal  tension . The supports carry the loads from the beam by  compression  vertically to the  foundations . A beam bridge, with forces of tension represented by red lines and forces of compression by green lines. Encyclopædia Britannica, Inc. When a bridge is made up of beams spanning between only two supports, it is called a  simply supported beam bridge. If two or more beams are joined rigidly together over supports, the bridge becomes  continuous. Truss A single-span  truss  bridge is like a simply supported beam because it carries vertical loads by bending. Bending leads to compression i

Bending Basics: The hows and whys of springback and springforward To a press brake operator, a  bending angle  is different from a  bent angle , and it all has to do with that ever-present forming variable: springback. Springback occurs when the material angularly tries to return to its original shape after being bent. When fabricating on the press brake, an operator will overbend to the bending angle, which is angularly past the required bent angle, compensating for the springback. Overbending to the bending angle allows the desired bent angle to be attained when the part is released from pressure. The tensile strength and thickness of the material, type of tooling, and the type of bending all greatly influence springback. Efficiently predicting and accounting for springback are critical, especially when working with profound-radius bends, as well as thick and high-strength material. The Science of Springback Why exactly does springback occur? There are two reasons. The first has to d

  How bridges balance forces Forces  make things move, but they also hold them still. It's far from obvious, but when something like a skyscraper looms high above us or a bridge stretches out beneath our feet, hidden forces are hard at work: a bridge goes nowhere because all the forces acting on it are perfectly in balance. Bridge designers, in short, are  force balancers . The biggest and most pervasive force in the universe, gravity, is constantly tugging things down, which isn't such a problem for a skyscraper, because the ground underneath pushes straight back up again. But a bridge spanning a river, valley, sea, or road is quite different: the huge  deck  (the main horizontal platform of a bridge) has no support directly beneath it. The longer the bridge, the more it weighs, the more it carries, and the bigger the risk it'll collapse. Bridges certainly do fall down from time to time, and quite spectacularly, but most stand happily still for years, decades, or even cent