EARTH QUACK RESISTANCE CONSTRUCTION TECHNIQUES
WHAT IS EARTH QUACK..?? They are natural disasters of a generally unpredictable nature. It is the shaking of the earth due to the movement of earth’s crust. A sudden, and rapid shaking of earth caused by the breaking and shifting of rocks beneath the earth surface. TERmS: Fault plane Hypocenter Epicentre SEISmOlOgy When earthquakes occur, waves travel in Earth in form of vibrations, such waves are called Seismic Waves. Study of such waves - Seismology. Instrument measuring seismic waves - Seismometer. Graphs given by that seismometer - Seismic Graph.
THERE ARE TWO EARTHQUAKES
TypES
Of
Inter plate Intra plate In both types of earth quakes both vertical (strike slip) and horizontal (dip slip) happens when there is fault Earth quakes are casually related to compression or tensional stress
fAUlT
A fault is nothing but the crack or weak zone inside the earth. When 2 blocks of rock or 2 plates rub against each other along a fault, they don’t just slide smoothly and due to tension, compression, bending and friction the rocks breaks
THERE ARE TWO TypES Of SEISmIC WAvES
Seismic performance is the ability of structure to sustain its function through safety and serviceability at earthquake BOdy WAvES P waves _ travels through solids and fluids S waves_ travels through solids SURfACE WAvES Slowest and damaging
ImpROvINg EARTHQUAKE RESISTANCE Of mINOR BUIldINg SIzE Of BUIldINg Simpler the plan, better the performance & single column, weak beam
CONSTRUCTION mATERIAlS Rcc is more preferable than pcc and horizontal band necessary
CONfIgURATION Of BUIldINg
The building should have a simple rectangular plan. Long walls should be supported by Reinforced Concrete columns Large buildings having plans with shapes like T, L, U and X should preferably be separated into rectangular blocks by providing gaps in between.
EARTHQUAKE RESISTINg STRUCTURES TECHNIQUES Base isolation Method Energy dissipation device (Seismic Dampers) Keeping building up thrust
SUggESSTIONS
Avoid weak column and strong beam design Provide thick slab which will help as a rigid diaphragm Provide cross walls which will stiffen the structures Provide shear walls in a symmetrical fashion Increase in the transverse (Shear) reinforcement. Horizontal lintel band should be provided Revision/ updation of building code of INDIA
The building must be regular and symmetrical in shape Reinforcing bars should be provided at the corners and the junctions of the walls
HOW EARTH QUACK AffECT BUIldINg…??? SHAKINg Ground moves in the same place lANd SlIdES Ground is moved to some another place lIQUIfACTION Strength of the ground is reduced causing buildings to sink
EARTHQUAKE RESISTANT dESIgNS
Design - it is analysis of forces buildings due to loads acting on it. If a building is enough to resist the earthquake, then such building is called Earthquake resistant structure . Such design is called Earthquake resistant designs
pOpUlAR EARTHQUAKE RESISTANT TECHNIQUES
Shear walls Bracing Seismic Dampers Isolation Bands Rollers Light weight material Others
SHEAR WAllS
Vertically oriented wide beams It carries seismic loads down to the bottom of foundation Provides large strength and stiffness to buildings. Thickness generally varies from 150 mm to 450 mm in high rise building
Should be symmetrical in plan along both the axes The opening provided in shear walls should be symmetrical Effective when located along the exterior perimeter of the building
TypES Of dAmpERS vISCOUS dAmpERS Reduce the vibrations by fluid action fRICTION dAmpERS Reduce the vibrations by rubbing action b/w surfaces TUNEd mASS dAmpERS Reduce the vibrations by harmonic action yEIldINg dAmpERS Reduce the vibrations by metalic components vISCOElSTIC dAmpERS Reduce the vibration by the absorption of utilising the controlled shearing of solids
BASE ISOlATION
Base isolated by a series of bearing pads which are placed between building and building foundation Lead rubber bearing is sandwiched between two steel plates Reduce the building acceleration by ¼ the acceleration of fixed base building Acceleration decreased because the base isolation system lengthens the building's period of vibration. Rubber is highly elastic so reduce the damage Converts the kinetic energy as heat
lOW COST BUIldINg mATERIAlS USEd dURINg pOST EARTHQUAKE HOUSINg CONSTRUCTION
Improvement of Mud • Post earthquake , mud houses are most effective since they are environmental friendly, cool in summer and warm in winter. • Mud is available in abundance free of cost. • Such types of houses are temporary in nature, prone to erosion by heavy rains. The disadvantages of mud can be overcome by suitable improvement in design and construction techniques. Stabilization • The strength of mud is improved by adding cement, lime, bitumen or fibers and it also becomes resistant to water. Non-erodable mud plaster • Non-erodable mud is prepared by mixing bitumen cutback (Bitumen & Kerosene oil mixture) with a specified mud plaster. Soil should consist of clay 20- 25%, sand 40-45%. Bitumen of 80/100 grade penetration and kerosene oil are mixed in the proportion of 5:1 (by weight) for preparing cutback. Non-erodable mud plastered walls are resistant to water erosion.
Terra-cotta skin to mud walls • To provide potter made tile lining to mud-walls protect them from rain and moisture. These tiles/bricks can be fixed with mud mortar & pointed with cement mortar Improved Thatch Roof • It involves plastering of thatch layers by the specified mud plasters. Top & bottom of the thatch roof is plastered with nonerodable mud plaster, which makes it durable & fire resistant. Wardha Tumbler Tiles • These tumbler tiles are cast by potters and used as roofing. • This kind of roof keeps the heat & cold out. • These tiles require no under structure, yet can bear the weight up-to 1-0 tonne/m2 . • Life is about 50 years & requires no repairs. • Being light in weight (135kg/m2 ), the roof is safe even in future earthquakes. .
Cement Bonded Fiber Roofing Sheets • Cement bonded fiber roofing sheets are made by utilizing coir waste coconut pith, wood wool etc., in combination with cement as binder for production of corrugated or plain roofing sheets. • These sheets require less cement and so they are cheaper than other roofing sheets available in the market Precast RCC Door and Window Frames • These are cheaper, stronger fire resistant, termite resistant and sustain temperature & humidity. Rice Husk as Building Material • India alone produces about 20 million tones of rice husk annually. Rice husk ash has been found to be a useful building material. • It can be mixed with cement up to 20% without affecting strength and thus cost of construction can be reduced and problem of disposal of this ash can also be solved by using it.
Pre-Disaster Preventive Measures Long-term measures • Incorporating earthquake resistant features in all buildings at high-risk areas. • Constructing earthquake-resistant community buildings and buildings (used to gather large groups during or after an earthquake) like schools, dharamshalas, hospitals, prayer halls, etc., especially in seismic zones of moderate to higher intensities. • Getting communities involved in the process of disaster mitigation through education and awareness. • Networking of local NGOs working in the area of disaster management. Post-Disaster Preventive Measures • Evacuation of people. • Medical care for the injured. • Supply of food and drinking water. • Temporary shelters like tents, metal sheds etc. • Repairing lines of communication and information. • Quick assessment of destruction and demarcation of destroyed areas, according to the grade of damage. • Inspecting damaged structures that are liable to collapse during aftershocks.
Do’s and Don’ts4 Before an earthquake • Pick couple of safe meeting places that are easy to reach. Practice Drop, Cover and Hold on in each safe place at least once a month. • Prepare an emergency kit and place it in a safe place. • Protect yourself, drop to the floor, take cover under a sturdy desk or table and hold on it so that it doesn’t move away from you. Wait there until the shaking stops. • Stay away from glass windows, heavy furniture and anything that could fall, such as lighting fixtures or other similar items. • If you are outdoors, find a clear spot away from buildings, trees, electrical lines and narrow streets. Drop to the ground and stay there until the shaking stop. • If you are in a vehicle, pull over to a clear location, stop and stay there with your seatbelt fastened until the shaking stops. Avoid bridges, flyovers or ramps that might have been damaged by earthquake. • If in costal area, move to higher ground and check tsunami warning. • If you are in a hilly areas be alert and move away from slopes in case of landslides and falling rocks. After an earthquake • Check up: radio, TV, online updates, social network for emergency information and safety guidance. • Don’t enter partially damaged buildings. Strong aftershocks can cause further damage to the buildings and weak structures may collapse. • Anticipate aftershocks, if shaking lasts longer than usual.
Post-Earthquake Relief, Rehabilitation and Reconstruction Measures undertaken by the Government
• Immediate Response: By enforcing the Essential Services Operation Government ensured the supply of essential goods and services to the affected region. • Relief, Rehabilitation and Reconstruction Measures • Cremation Cost and Assistance to the Family of Victims • Temporary Shelters/Rehabilitation of those Rendered Homeless • Rehabilitation and Reconstruction Plan Priority Items: priority items (that cover shelter, food, hygiene, clothes; drug and surgical items and construction; emergency veterinary medicines, vaccines, disinfectants and feeds; and agricultural nutrients) required in connection with the immediate relief operations. • Injured in the Earthquake • Data Collection: With a view to collecting data on the loss of lives/properties with all vital details, the Government has sent various teams to the affected districts. • Call for Contributions to PMDRF: The Government has advised all the contributors (countries, organizations and individuals) both at home and abroad to contribute to the Prime Minister's Disaster Relief Fund (PMDRF) to reach out to the real victims of the earthquake.