EARTHQUAKE RESISTANT Design Presented By: Probin Bhowmick Under the guidance of: Prof. Jayashree Sengupta Department of Civil Engineering Supreme Knowledge Foundation Group of Institutions

WHAT IS EARTHQUAKE ? Earthquake is a natural phenomenon occurring with all uncertainties During the earthquake, ground motions occur in a random fashion, both horizontally and vertically, in all directions radiating from epicenter These cause structures to vibrate and induce inertia forces on them

CLASSIFICATION Slight: Magnitude up to 4.9 on the Richter Scale Moderate: Magnitude 5.0 to 6.9 Great: Magnitude 7.0 to 7.9 Very Great: Magnitude 8.0 and above

Earthquakes facts According to the United States Geological Survey, more than three million earthquakes occur every year That's about 8,000 a day, or one every 11 seconds The vast majority of these 3 million quakes are extremely weak It is the big quakes that occur in highly populated areas that get our attention It's not the shaking ground itself that claims lives -- it's the associated destruction of man-made structures and the instigation of other natural disasters, such as tsunamis, avalanches and landslides

CAUSES Heavy dead weight and very stiff buildings, attracting large seismic inertia forces. Very low tensile and shear strength, particularly with poor mortars. Brittle behavior in tension as well as compression. Weak connection between wall and wall & roof and wall. Stress concentration at corners of doors and windows. Overall un symmetry in plan and elevation of the building Un symmetry due to imbalance in the sizes and positions of openings in the wall. Defects in construction, such as use of sub standard materials, unfilled joints between bricks.

The Basic Theory of Earthquake The surface layer of the earth -- the lithosphere -- is comprised of many plates that slide over the lubricating asthenosphere layer At the boundaries between these huge plates of soil and rock, three different things can happen Plates slide against each other Plates can move apart Plates can push together

Faults Faults -- breaks in the earth's crust where the blocks of rock on each side are moving in different directions Earthquakes are much more common along fault lines than they are anywhere else on the planet Few types of faults, characterized by the position of the fault plane, the break in the rock and the movement of the two rock blocks

Faults Are Divided In To Three Parts Normal fault Reverse fault Thrust fault

In a normal fault, the fault plane is nearly vertical The hanging wall, the block of rock positioned above the plane, pushes down across the footwall, which is the block of rock below the plane The footwall, in turn, pushes up against the hanging wall These faults occur where the crust is being pulled apart, due to the pull of a divergent plate boundary

Reverse fault In a strike-slip fault, the blocks of rock move in opposite horizontal directions These faults form when the crust pieces are sliding against each other, as in a transform plate boundary

Thrust fault moves the same way as a reverse fault, but the fault line is nearly horizontal In these faults, which are also caused by compression, the rock of the hanging wall is actually pushed up on top of the footwall This is the sort of fault that occurs in a converging plate boundary

Earthquake Resistant Buildings Earthquakes can cause buildings to vibrate Every building has a number of ways, or modes, in which it can vibrate naturally. In each mode, the building vibrates to and fro with a particular distorted shape called its mode shape. Earthquakes usually make buildings vibrate most strongly in their fundamental mode, the mode of vibration with the lowest frequency Earthquake Resistant Buildings

Seismic Risk To Building In India The construction may generally be classified into two types: Non-Engineered Construction: Ex un reinforced brick masonry, stone masonry Semi -Engineered Construction: Ex Reinforced brick masonry Engineered Construction: Ex Reinforced Concrete framed structures or steel structures.

Classification Of Seismic Zones In India

Seismic Effects On Structures

Horizontal and Vertical shaking

Behaviour Of Brick Masonry Wall Ground vibrations during earthquakes causes inertia forces to travel through the roof and walls to the foundation. The main emphasis is on ensuring that these forces reach the ground without causing major damage or collapse. Of the three components of a masonry buildings, walls are most vulnerable to damage caused by horizontal forces due to earthquake.

Improving Behaviour Of Masonry Wall Box action: A number of construction aspects are required to ensure box action Ensuring good interlocking of the masonry courses at the junction. Employing horizontal bands at various levels, particularly at the lintel level

The size of the doors and window opening need to be kept small. The smaller the opening, larger is the resistance offered by the wall

Tips For Earthquake-resistant Design The building plan should be in a regular shape such as square or rectangular. No wall in a room should exceed 6.0m in length. Use pilasters or cross walls for longer walls. In hilly terrain, it should not exceed 3.5m in length. The height of each storey should be kept below 3.2m. Don’t use bricks of crushing strength less than 35kg/cm2 for single storeyed building and of 50kg/cm2 for 2-3 storeyed building. Only solid and sound bricks/ concrete blocks should be used Provide a R.C.C band of 4” thickness throughout the run along wall at lintel level passing over doors and windows. The thickness of load bearing wall should be at least 200mm The clear width between a door and nearest window should not be less than 600mm. Location of a door or window from edge of a wall shall be 600mm minimum.

Conclusions Earthquake resistant construction is important in earthquake prone area The building can resist earthquake forces with almost no damage The building shall not collapse or harm human lives during severe earthquake motions. However these structures will be uneconomical.

Earthquakes in the world As the Nation's largest water, earth, and biological science and civilian mapping agency, the U.S. Geological Survey (USGS) collects, monitors, analyzes, and provides scientific understanding about natural resource conditions, issues, and problems. Earthquake Hazards Program Latest earthquake in the world

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