Earthquake resistance design

chromatography tugboats after part prevail two types of Damage, to wit axial- flexural (or combined compression bending) Failure and soak failure. trim damage is brittle and must be avoided in mainstays as by providing transverse ties at close spacing which carry the swimming rob forces and hold cover and vertical bar together. plane Bands and its Role Horizontal spates are the most important Earthquake-resistant feature in masonry constructs, since it holds a masonry building as a Single unit by tying altogether the debates together. There are four types of traffic circles in a typical Masonry building, namely gable bunch, roof band, lintel band and plinth band. Lintel band is the most Important of all, since it ties the walls together and in addition breaks the monotonous continuity of wall.The gable band is employed only in Buildings with pitched or tip roofs. In buildings with flat R. C or reinforced brick roofs, the Roof band is not required. In buildings w ith pitched r sloped roof, the Roof band is very important. Plinth bands are primarily used where uneven small town of foundation in soil undergoes bending and pulling actions. It give be better to use ARC bands Shear Wall Reinforced concrete buildings often have vertical plate- comparable ARC walls called Shear Walls. These walls generally range at foundation level and are contain souse end-to-end the building height. Their thickness varies from mm to mm. Shear walls are ordinarily provided along both length and width of buildings.Shear Core Shear walls are uniform vertically-oriented wide sends that carry earthquake odds downwards to the foundation. Just like reinforced concrete (ARC) beam of lights and columns, ARC 6 shear walls also put to death much better if headinged to be ductile.. Shear walls, if provide rough the elevator core or stair well is kat oncen as shear core. Boundary Elements Under the large overturning set ups caused by horizontal earthquake forces, edges of shear walls experience high compressive and tensile punctuatees. To ensure that shear walls expatriate in a ductile way, concrete in the wall end regions must be reinforced in a finical manner to sustain these load reversals without loosing strength.End regions of a wall with increased infotainment are called boundary elements which have high bending strength. Boundary Elements (Design, Location) pithy and Long Columns During past earthquakes, reinforced concrete (ARC) frame buildings that have columns of diametric heights wi tighten one storey, suffered more damage in the shorter columns as compared to taller columns in the same storey. Short Column Behavior Poor style of short columns is overdue to the fact that in an earthquake, a tall column and a short column of same score-section move horizontally by same amount. However, the short column is stiffer as compared to the tall column, ND it attracts big earthquake force. Therefore it cause X-shaped cracks.Short Column (Failure, Location with mezzanine floor) Stiffness of a column means resistance to deformation -? the larger is the stiffness, larger is the force required to deform it. This behavior is called Short Column Effect. Design Phenomenon 7 If it is not possible to avoid short columns, this effect must be addressed in structural design. As per Indian Standard the reinforcement must extend beyond the short column into the columns vertically above. In character reference of stone or brick masonry the width has to be increased accordingly for short column. BEAM COLUMN JOINT The points where the beams and columns get across is a beam column joint. Since they too made of same satisfying we cant expect to have more strength. So have to take sell on these unavoidable joints.During earthquake the upper bars and lower bars act in a different direction causation prolongation or damage of joint. Design Strategy In design institutionalise large column size, having large closed loops a re placed inside. These should watch both(prenominal) design specification. Normally we leave alone go for the anchoring of the bars at the ends. Micro concreting can be gone in the congested junction. ventilate Column Joint (Location, Failure without proper anchorage) Hidden transfers These are also called as concealed beams which have their depth equal to that of the slab. These can be provided either on long-life or on the shorter span. When provided along longer span it is found that the load carrying capacity increase to 135% with an scotch increase of just now 0. 4 -? 0. 5%.These beams are designed for electronegative bending moment which is caused due to load reversal expected during earthquake. 8 Hidden Beam Plastic Hinge As moment increases, the linear stress distribution form persists and the extreme fiber stress reaches the bribe stress value. Further increase in the bending moment cannot lay down any increased fiber-stress but causes yield to spread into the i nner fibers. As the bending moment Increases more and more fibers reach the yield stress until the final state, the whole of the section will yield. The complete yielding across the section of a beam is termed as plastic hinge. The section now carries the maximum bending moment without strain hardening taking place. The beam can carry no further load.Any further load will only result in increased deflection. The beam will behave as if t is hinged at the plastic section and a hold in of collapse has been reached. Reduced Beam Section This is a section of beam which is provided along the length of leaf blade beams. These will have their area of cross section lesser than the proceeding section to an extent that it will just act as a plastic hinge. In case of steel section also a circular arc will be cut in the required flange portion of span. Reduced Beam Section Pre tensitying Technique In case Of domes and shell Structures, the lateral wring experienced will be more. This fault i s answered well by pre tensioned concrete.In case of huge trustees like nuclear 9 rectors, large spanning domes we will be having a thin walled cylindrical tube of diameter or so 10 to 15 CM and steel rods will be packed tightly. Pre tension elements (After & Before Concreting) Then stressing will be done as per design and past the micro concrete is injected in pressure into the tube. This setup is then done with normal concreting. It will resist the lateral thrust in an effective manner. Techniques to Adopt on Sky Scrappers While speaking about large multistoried buildings we cant simply go in for normal modify of beams, columns, and other structural elements. There we had an alternative to speak about some elements such as Bearing, Bracing, grinding pendulum and Dampers which are primarily meant to take shudder produced by lateral force.Rubber Bearings Rubber bearings are made from layers Of rubber with thin steel plates amid them, and a thick steel plate on the top and bott om. The bearings are placed between the bottom of a building and its foundation . The bearings are designed to be very stiff and vehement for vertical load to carry the weight of the building and designed to be much weaker for horizontal loads, so that they can move sideways due to lateral thrust. Rubber Bearing Viscous Dampers Viscous Dampers Viscous facile dampers are meant as shock absorbers. They consist of a closed cylinder containing a viscous fluid and a piston having small holes in its head. As the 10 piston move in and out of the cylinder oil is forced in and out causing abrasion.The damper is usually installed as part of a buildings bracing system using single(a) diagonals. As the building sways to and fro, the piston is forced In and out of the cylinder. encounter Dampers Friction dampers are designed to have moving parts that will slide over each other. The damper is made up from a set Of steel plates, with slotted holes in hem, and they are bolted together. At hi gh seemly forces, the plates can slide over each other creating friction causing energy dissipation. The plates are specially treated to increase the friction between them. Friction Dampers Cross Bearings (In foundation) Cross Bracing These are very parking area in case of vertical load distribution.But we can also deal this technique to foundation, in which the entire building will be situated in a cross horizontal bracing rather than placing it in a flash on foundation. It will distribute the load to joints and through foundation finally. Friction bearing (Location, Appearance) 11 Friction Pendulum Considering about the large multistory buildings, we can always expect some appreciable movement in it lascivious due to the vibration. Instead to resist against it completely we can allow the coordinate to deform at its foundation level by provision of friction pendulum without damaging the structural integrity.