 This is Mr. Chetan G. Munapure, assistant professor, department of civil engineering, Vulture Institute of Technology, Solaapur. Now, this is the learning outcome for the student. At the end of the session, student will be able to describe the design spectra of IIS 1893 2016. Now, let us see what is the earthquake design earthquake specification. So, what is the earthquake which is considered in the code that code earthquake is defined using two parameters. Most important is the peak acceleration, even we can see peak ground acceleration that is z which is specified in the code. Second is the frequency content that code earthquake is defined by using these two parameters. So, IIS code specifies different peak ground accelerations based on the seismic zone. Our country is divided into four zones. So, the seismic zone map of India is shown in 1893. So, z these are the zones 2345, zone 1 was there, but it was now removed from the IIS revision and directly it is started from zone 2 and these are the z factor zone factors for these four zones. Now, our solapur city belongs to zone 3, so zone factor for solapur city is 0.16. Now my question for all of you students because most important thing that we are going to discuss here about the design earthquake, my question is for you that which parameters are used to define code earthquake. We are talking about the code earthquake. So, first you think of that while defining the code earthquake, what is considered? A, B options are given, C option is also given, D option is also given. So, what is the, which are the parameters that are these are considered to define the code earthquake? What was the video, just think of that and give the answer. The answer is, see that is a peak acceleration and frequency content. Both these two parameters are used to define the code earthquake. Now, let us see this design spectra. This design spectra is explained in our 1893 and for equivalent static method, the design spectra is given. In earlier code 1893-2002, only one spectra was given that was this design spectra. Now, it is also there, but for equivalent static method, but that I am discussing first. Now, this response spectra specifies frequency content of the earthquake forces. So, again that the response spectra is specified as spectral acceleration versus time period. What is this plot? Spectra means the plot or graph that plot is having the response quantity of acceleration on y axis, SA by G that is on y axis and on x axis time period of the building. That is in second. So, we have to find out the time period of our building and that based on the time period, we will get the spectral acceleration coefficient on y axis. So, this is design spectra. So, initially there the linear line is there, then the constant line which is having highest value of SA by G and then the curve is there and it is constantly reducing. Now, let us see the zones of this response spectra. First zone is this much, this 0 to T1, this zone in which the SA by G is proportional to T. Second zone T1 to T2 it is constant which is having highest level of SA by G. Third is then it is proportional, this portion after T2, this portion is proportional to inverse of T or 1 by T. So, as T will increase after T2, your SA by G will reduce the meaning of this diagram and for this zone after T3, this zone is constant. So, it is remaining as it is as T is increasing your SA by G that will remain same after T3. Now, this design spectra, the portion of the response spectra proportional or governed by first ground acceleration. This portion means 2.5 which is very highest value of SA by G, this portion is governed by the ground acceleration. Next velocity, this portion means after this block or this constant line, this parabolic profile, this parabolic profile that is governed by the velocity of parameter of the earthquake shaking, earthquake vibration. Fourth displacement, now after T3 means a constant portion that is governed by the displacement of the shaking. So, these portions how these are proportional are governed by the motion parameter that is explained in this diagram. Now, code earthquake specifications, design earthquake that design earthquake means the design spectra, it is obtained from the product of design spectra and peak acceleration. So, design earthquake how we are ensuring, how we are determining that is from the product of design spectra and peak acceleration. So, SA by G that is the design spectra or value from the design spectra peak acceleration is Z. So, Z in SA by G that gives you design earthquake. So, whenever we are taking SA by G from the response spectrum sorry and if you multiply by the peak acceleration, so that is design earthquake. Next is code design spectra is further modified to account for building importance factor I and dectility of structural system R. We are if you incorporate I and R in this calculation, then whatever earthquake that we are determining or modifying that is called as code design spectra. SA by G the response spectra multiplied by Z that will give design earthquake and then if you incorporate I by R that gives you code design spectra, different values or suggestions are given regarding why I is taken how it is it is in between A to 1 to 1.5 R is in between 1 to 5, then their ratio all those things are, but most important formulation that is explained here. Now, let us see the actual theme in this design spectra why I have taken this discussion for you. There are three records actual earthquake records. So, this blue line Northridge earthquake in 1994 this record is shown here on y axis SA by G on x axis time period is there. Now, this green line that is all centro earthquake this is the record of all centro earthquake. How much randomness is there that you can see next thing is the rock spectra. So, rock spectra I think this line it is a light blue. So, this line is rock spectra spectra for the from the different records and next is your design rock spectra R is equal to 5, 4 design spectra is here actual earthquakes are having this values or this record. If you observe that design spectra is much lower than actual spectra or actual earthquake real earthquakes may have a much higher response spectra ordinates than our design spectra. So, this actually I have discussed in the design philosophy why this types of spectras are paid. Now, the randomness that was removed with response spectrum is prepared for use. So, this is the actual profile. So, actual earthquake is at this level blue line ok. Next is this is our core spectra core spectra means the response spectrum spectra which we are using for SA by G. After that we are multiplying by the several factors R and Z by 2 all those things are winning then it is going at this level. So, design spectra is at this level actual earthquake is at this level. So, there is a difference of in between the actual earthquake and design earthquake ok. So, this plot explains you that we are designing our building structures for this level wherein this is actual earthquake. What why that what is the difference or why this design spectra is prepared which is very having large difference between the actual earthquake and this design spectra ok. The reasons are given here use of much lower design spectra has been adopted based on several reasons following are the reasons why lower design spectra has been adopted what is the reason behind that design earthquake has very low probability during life of the structure ok. So, the our RCC structures are having their life actually actually it was 80 years. So, 60 to 80 years that life here we are considering and the whatever design earthquake we are considering it is having very low probability during its life of structure. Design wind has written period of 100 years versus 475 years for earthquake. So, in case of wind load analysis the probabilities of 100 years return period, but in earthquake case even for design earthquake it is 475 years. So, in 475 years it may return which 475 that is not also clear. Next is the structural system have redundancy and additional margins. So, our structures have redundancy and the additional margins over strength is also there. Structure materials have additional margins means over strength of the material means concrete and steel the full strength of the concrete and steel we are not taking. Structural members can sustain few cycles of inelastic deformation if designed as ductile members. These are the reasons for which we are going for design spectra than actual spectra ok. So, in RCC members here partial safety factor is 1.5 and for fck this is the stress strain curve of RCC member for concrete and 1.5 the partial safety factor. So, it has become 0.67. So, we are reducing the strength of that material strength of that section and this is for steel partial safety factor for steel is 1.15. So, f y that we are not taking we are taking 0.87 f y. So, the material strength we are taking at reduced level by partial safety factor those strengths or margins are with us. So, now this is the margin in RCC members especially for the concrete material characteristic strength of the concrete that is considered when 5 percent cubes results only are allowed to fall below the grade of concrete. Grade of concrete how it is established 95 percent of results are above the grade not equal to grade above grade. Then that above grade or 95 percent results are there means there is over strength in the concrete available for the concrete material. These are the references for this session. Thank you.