 Welcome to the session earthquake resistant design philosophy. This is Mr. Chetan J. Kunapuri, Assistant Professor, Department of Civil Engineering, Walshchand Institute of Technology, Swalapur. These are the learning outcomes for the students. Those students will be able to demonstrate the concept of earthquake resistant design and they can apply the conceptual design features in the structures. Now, why civil engineering structures are affected? This is the first question in the earthquake. What is the basic problem in that the structures are severely affected by the earthquake? Now, most structures are having their time period, which is very near closer to the time period of earthquake vibration. That is the basic reason. So, when the time period of the structure as well as earthquake are matching, so resonance effect will arise and that is why the structures are severely affected. Now, next thing is explained in this figure number 1. You can see this flow chart in this figure, it is very small. Input, some media is there and output is there. Now, ground motion is input that is the earthquake and the output is amplified structure response. Generally, these are deformations, but in between the ground motion input and output of amplified structure response, basically this intermediate part is structure properties. Now, if proper structure properties are selected or designed, this may act as a filter which will reduce the output means structural response or if they are improper, structure properties are improper in appropriately designed, then this will act as amplifier also and you will get very high response, high deformations. Now, the design philosophy of earthquake and the basic facts which are on which the philosophy is based, that is first thing is earthquake proof construction is practically impossible. So, we are using the earthquake resistant term, we are not using earthquake proof term, proof construction is practically impossible. Now, second thing is that the structures to resist more severe shaking will be very expensive building, which will not be even economical also and last is most severe earthquakes are not frequent also. Suppose, we if we design the structures for the most severe earthquake, probably in the entire period of or life of that structure the earthquake may not happen or earthquake may not repeat also. Now, what are the objectives behind this philosophy? Every philosophy is based on some objective or what the structure should do when the earthquake will happen or how the structure should perform. Here different earthquakes are categorized and the expected performance of the structure is also shown here. Now, first is the minor and infrequent earthquakes, the minor earthquakes are frequent in nature. So, there should not be any damage should not be any damage for the structure. For moderate earthquakes no structural damage some non-structural damage, no structural damage means structural element should not have any damage, non-structural damage means the plaster cracking, ceiling plaster falling parapet damage these are expected, but the structural element should remain intact without damage. Last is severe and infrequent earthquake. Structural damage is expected. Some damage to the structure remains is also expected for severe and infrequent earthquake, but no collapse based on these performance of the structure the philosophy is made. Now, the design philosophy actually it is based on dual design philosophy with the earthquake resistant design which are the there are two design philosophies or sorry two dual objectives. First is safety level design, second serviceability level design. How the safety of the structure is ensured? Safety of the structure is not compromised at for any type of earthquake there though there may be extreme earthquake events, but our structure must remain safe in that also. Second is serviceability design means what if frequent earthquakes are there, if moderate earthquakes are also there. In those moderate or frequent earthquakes also our utility service lines of the structure shall not be disrupted shall not be damaged. So, one is safety level, second is serviceability level. In one case extreme earthquake concentration is there in safety level design. In second case in serviceability level design moderate and frequent earthquakes are considered. So, these two are the dual design philosophies for earthquake resistant design. Now, how it can be ensured? Design codes endure to satisfy both performance requirements means safety level design requirement, serviceability level requirement and this is possible through a combination of proper analysis, design and detailing specifications which already the code has covered. Now, next is design earthquake. Now, design earthquake events are required for both the performance criteria. Design earthquake means suppose in a particular zone particular area of any extreme earthquake happened in history or from the historical record any earthquake is there which is very extreme earthquake. Can we design the structures for of that area for that extreme earthquake? So, in that case your structure will be practically we cannot construct it may be very heavy or economical also. So, what should be the earthquake level which we should consider for our designs? So, there are two categories one is extreme earthquake event second is moderate earthquake event which we should consider for the analysis and design which is considered in the course also. Extreme earthquake event means it is termed in our code as maximum considered earthquake in that particular zone. The abbreviation is MCE. It has very low probability of occurrence and it must not result in excessive casualties and damage also. The probability of this earthquake in the 50 years is 2 percent and from the probabilistic approach the data is given that it may return once in 2005 years on an average. Now, what is the moderate earthquake event? This is termed as design basis earthquake in our code and it has moderate probability of occurrence. It must result in a moderate and repairable damage most important thing is the damage which is repairable means for even for structure or non-structural element the damage happens it can be repaired. It must result in very few casualties and the probability of occurrence is of 10 percent. So, after the probabilistic approach whatever return period is calculated that is once in 475 years on an average. Now, so extreme earthquake is there moderate earthquake for which we should design. We should consider that earthquake which we should have some proper level and that is called as design earthquake. Now, this design earthquake event have been decided based on PARC earthquake data. This is the first preliminary work to decide any design earthquake for a particular area. Earthquake severity has been classified on the basis of maximum or even it is termed as a peak ground acceleration PGA also it is it is also called as PGA. Now, our country has divided into four seismic zones and these seismic zones are actually based on their peak ground accelerations or even the earthquake hazards. Now, in those zones zone 2 has very lowest hazard and zone 5 has very highest hazard. Now, let us first see for the example Mumbai city, Solaapur city falls in seismic zone 3 Delhi falls in zone 4 and Bhuj so, earthquake happened in Bhuj. So, that is why this is also the important earthquake which already always considered in the earthquake analysis and design it is in zone 5. All these things are shown in seismic zoning map of IS 1893 2016. Let us see this seismic zoning map. So, this is the zoning map of 1893 you can see here. So, entire country is divided into four seismic zone zone 2 3 4 5. So, this Kashmir Himalayan build and this area belongs to zone 4 and 5. So, this taken plateau actually it was considered earlier in earlier era it was considered as a seismically inactive. Now, this zone this area belongs to zone 2 and zone 3. So, Solaapur is in zone 3. Now, peak ground acceleration maximum considered earthquake in each seismic zone have been decided from seismic tectonic studies or past experience and basically the maximum considered earthquake peak ground acceleration is divided by 2 and that PGA is considered for design basis earthquake. The frequency content of ground motion is assumed the same for both the earthquakes or MC and DB frequency content will be the same. Now, structures are explicitly designed for design basis earthquake and the safety under maximum considered earthquake is ensured through suitable over strength of the sections and activity provision. So, the wide activities required why the structure must deform more the basic reason behind that we are designing our structure for DB design basis earthquake and we are ensuring the safety of the structure under maximum considered earthquake. Now, there is one question for you all of you just pause the video and answer this question what is the relationship between the peak ground acceleration of design basis earthquake and maximum consider earthquake just answer it. The answer is the peak ground acceleration of design basis earthquake is assumed half the peak ground acceleration of maximum considered earthquake. So, you note it. Now, let us see what are the conceptual design features. Now, we are in the design features section the second outcome. Now, in good conceptual design aspect first is your the plan must be very simple as well as elevation must be simple and regular. You should go for the modular planning symmetry must be assured in plan as well as in elevation. Why it is so the basic reason whenever we go for these features we will get directly the moderate stiffnesses and strength and the very uniform stiffness and strength that will ensure the integral action of the building. So, there should not be any significant stiffness and strength in non uniformly along the height of the building also. Now, structural system should have should strike a balance between functional and structural requirement. Okay, we need some cantilevers okay what should be the cantilever dimension that is important. Functionally if we need cantilever structural requirement cantilever must be very small. So, this should be matched there should be the balance in functional requirement and cantilever sorry structural requirement. These are the references for this session. Thank you.