1. Background. 2. Objectives of Project. Page 1 of 29

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1 1. Background In close collaboration with local partners, Earthquake Damage Analysis Center (EDAC) of Bauhaus Universität Weimar initiated a Turkish German joint research project on Seismic Risk Assessment and Mitigation in the Antakya Maraş Region (SERAMAR). In this context, the instrumental investigation of buildings being representative for the study area becomes an essential part of the project to calibrate the models and to predict reliable capacity curves as well as scenario dependent damage pattern or failure modes. Based on different decision criteria, three multistory RC frame structures have been chosen and equipped with modern Seismic Building Monitoring Systems (BMS) each of which consists of four triaxial strong motion accelerometers of type MR After a 2 year test period, first results from the permanent instrumentation are available and provide a preliminary basis to reinterpret the structural response under seismic action. Into the project one of these buildings (see Fig.1 and 2) will be investigated and measured data will be analyzed in detail. The main purpose of this project will be to apply as much of the theoretical background taught during the lessons on Earthquake Engineering and Structural Design and Seismic Monitoring. 2. Objectives of Project - The interpretation of the structural system in view of earthquake resistance (ERD). - The design and analysis of the structural system using the software ETABS Nonlinear for the given building layout with (a) and without (b) masonry infill walls. - The analysis of the instrumental vibration data in order to identify dynamic structural parameters. - The comparison of the experimentally gained results with outcomes of the structural analysis. - The proposal of strengthening and retrofitting measures. Page 1 of 29

2 3. Layout and Geometry Figure 1. 5 storey building Figure 2. Site plan Page 2 of 29

3 - story height (of each story) : 3,00 m - thickness of slabs : 0,12 m - thickness of stair and stair platform : 0,15 m - outer masonry infill walls : 0,20 m - inner masonry infill walls : 0,20 m Grid Coordinate Y direction X Direction Axes [m] Axes [m] A B C D E F G H I J K L M N O P Q R S T Table 1. Grid coordinate of structure Page 3 of 29

4 Cross section of structure elements Figure 3. Cross section of elements Page 4 of 29

5 4. Material Properties Reinforced Concrete : Young s modulus : 2,80e+07 kn/m² Poisson ratio : 0,2 Mass density : 2,55 t/m³ Weight : 25 kn/m³ Concrete Strength : kn/m² Steel Strength : kn/m² Masonry: Young s modulus : 2.1e+6 kn/m² Poisson ratio : 0,15 Mass density : 0,918 t/m³ Weight : 9,0 kn/m³ Masonry Strength : 0.60 MN/m² 5. Loads 5.1 Dead Load and Live Load Based on the purpose of the project the following loads will be applied: 2,0 kn/m² on the roof as load for the roof construction 1,0 kn/m² on the floor slabs as load for interior etc. For the purpose of strengthening and retrofitting it s necessary to apply loads according to the requirements from EC 1 and the application of the load combinations according to EC 8. Figure 4. EARTHQUAKE ZONES ACCORDING TO THE TURKISH NATIONAL SPECIFICATIONS FROM 1998 Page 5 of 29

6 5.2 Design spectra (acc. to EC 8) for Zone 1, Turkish earthquake zoning map To design a building to withstand earthquake loading according to EC 8 in the initial stage a design or demand spectrum must be established in order to calculate the horizontal forces the building will be subjected to. The design spectrum as specified in EC 8 depends on: the soil type the structure is built on, the order of earthquake magnitude (Surface wave magnitude MS > or <= 5.5), the maximum ground acceleration to be expected at the site. According to the Turkish Earthquake Zoning Map in the National Specifications from 1998 (Fig. 6), the town of Antakya is located in zone 1, which poses the highest demands regarding earthquake safety. The peak ground acceleration given for this zone is 40 % g, or m/s 2 (4 m/s 2 ). For the design shall be used ground type B. Ground Type S TB (s) Tc (s) TD (s) A B C D E Table 2. Value for the response spectra type 1 (acc to EC.8) 5.3 Time History Data Figure 5. Elastic design spectrum Euro Code The time history data are taken from seismograph measurement which was placed on basement. In this calculation, the channel 3 on basement and channel 1 on the top are used to have response spectra which is displayed as following graphs below: Page 6 of 29

7 figure 6. Response Spectrum recorded from Top and Bottom Channel Page 7 of 29

8 Figure 7. Response Spectra from Matlab Page 8 of 29

9 6. Calibration of Response Spectra According to the Time History data above, before doing Pushover with ETABS software, we should calibrate the response spectra which are produced by MATLAB and ETABS. If the result is relatively similar, it means, the material properties and dimension of structure are nearly reality. Figure 8. Calibration of response spectra between Matlab and Etabs Page 9 of 29

10 7. Wall as structural elements Reliable predictions of the seismic response of building structures with infilled frames are not possible without taking into account the effects of infills. Unfortunately, modern seismic codes, including Eurocode 8, neglect these effects or take them into account to a very limited extent. The main reason for this situation is the lack of a simple and robust numerical methodology for analysis and design of frame structures with infills. According to FEMA 306, the diagonal braces for infill is calculated as following below: Effective width of diagonal (a) Where: t inf E me E fe I col ( λ ) 0.4 a = h. r h tan 1 inf Θ= Linf 1 col inf E. t.sin2θ me inf 1 = 4. EfeIcolhinf = Thickness of infill panel and equivalent strut = Expected modulus of elasticity of infill material (2.10e+6) = Expected modulus of elasticity of frame material = Moment of inertial of column λ 14 Bracing a h col r inf E me t inf E fe I col h inf L λ inf [m] [m] [m] [kn/m 2 ] [m] [kn/m 2 ] [m 4 ] [m] [m] Θ sin 2Θ E E E E E E E E E E Table 3. Infill calculation 8. Period X Direction Y Direction X Direction Y Direction with infill with infill without infill without infill Mode Period Period Period Period Page 10 of 29

11 9. Pushover Design 9.1 Capacity Spectrum Method To use the capacity spectrum method it is necessary to convert the capacity curve, which is in terms of base shear and roof displacement to what is called a capacity spectrum, which is a representation of the capacity curve in Acceleration Displacement Response Spectra (ADRS) format. The required equations to make the transformation are: miφ i i1 α = N N wi 2 miφi 1 i= 1 g i= 1 Sa Vb 1 = S g w α Where: 2 d Δroof = MPFϕ γ = MPF = mφ i i miφi 1 1 roof 1 MPF 1 = Modal Participation Factor for the first natural mode. α 1 = modal mass coefficient for the first natural mode W i /g = mass assigned to level i φ i1 = amplitude of mode 1 at level i N = Level N, the level which is the uppermost in the main portion of the structure. V = base shear W = Building load weight plus likely live loads Δ roof = roof displacement (V and the associated Δ roof make up points on the capacity curve S a = Spectral acceleration S d = Spectral displacement (S a and the associated S d make up points on the capacity spectrum 9.2 Demand Spectrum The general process for converting the capacity curve to the capacity spectrum, that is, converting the capacity curve into the ADRS format, is to first calculate the modal participation factor (MPF1) and the modal mass coefficient a1 using equation above. Then for each point on the capacity curve, V, droof, calculate the associated point Sa, Sd on the capacity spectrum using equations above too. In the ADRS format, lines radiating from the origin have constant period. For any point on the ADRS spectrum, the period, T, can be computed using Page 11 of 29

12 T Sd 2 2 S = 2π T = 4π S S a d a Then the spectral displacement is S d 2 T Sa 2 = 4π When period in the inelastic displacement, the relation between spectral acceleration and displacement is S C C Sa C S C x9, C g T g 2 4 g S S π π S Sa a v v v a v v = = = = = 2 2 S 2 Sd 4 π * d d d According to Euro Code 8 C = a * S* η *2.5* T a v g c Figure 9. Illustration of Demand Spectrum 9.3 Construction of Bilinear Representation of Capacity Spectrum A bilinear representation of the capacity spectrum is needed to estimate the effective damng and appropriate reduction of spectral demand. Construction of the bilinear representation requires definition of the point a and d. This point is the trial performance point which is estimated by the engineer to develop a reduced demand response spectrum. Page 12 of 29

13 If the reduced response spectrum is found to intersect the capacity spectrum at the estimated a, d point, then that point is the performance point. The first estimate of point a, d is designated a p1, d p1, the second point a p2, d p2, and so on. figure 10. Illustration of bilinear calculation To calculate the effective damng at several point around point d. Gradient pasca elastic from bilinear curve is computed by equation: Post yield slope = ' a a y ' d d y At point a, d, then the gradient of pasca elastic is computed by: Post yield slope = a d a d Because of gradient is constant, then: ' a a y ' a = ( )( ) y d d d y d y y y + a Page 13 of 29

14 Figure 11. Derivation of damng for spectral reduction Figure 12. Derivation of energy dissipated by Damng, ED ED = 4*(a.d 2A 1 2A 2 2A 3 ) = 4*(a d a y d y (d d y )(a a y ) 2d y (a a y )) = 4*(a y d d y a ) According to the graph above, Eso = a d /2 β o = 4( ad y da y ) 1 4π a d 2 Effective viscous damng is: 63.7κ ayd d β eff = 5+ kβ 0 = 5 + a d = ( ad da ) 63.7 y y a d ( a ) y Page 14 of 29

15 Performance point Capacity spectrum a' ay 5% Damped response spectrum dy d' Spectral displacements, inches Figure 13. Performance point Value for damng modification factor (κ) Structural Behavior Factor β 0 κ Type A Type B > > ( ad y dd y ) 1.13 a d ( ad y dd y ) a d Type C Any value 0.33 Table 4. Value for damng modification factor (κ) 9.4 Numerical Derivation of Spectral Reductions The equations for the reduction factors of acceleration (SRA) and velocity (SRV) are given by: SR A = SR V = 3,21 0,68ln ( βeff ) 2,12 2,31 0,41ln ( βeff ) 1, 65 Page 15 of 29

16 Structural Behavior Type SR A SRv Type A Type B Type C Table 5. Structural behavior value Figure 14. illustration of Performance point determination When Period of 5% damped spectrum is in acceleration range, then When period (Ts) of 5% damped spectrum starts changing from constant acceleration range to constant velocity range, then T s Sa 2,5SRAC g = SRv * Cv = S a S 2 Sa Ts d = = S 2 a ω A ( ) 2 S SR *C SR *C SR *C. a v v v v g v v 1 = = = g Ts S 4π 2 S d d 2π S a 2π T=2π s S S d a Page 16 of 29

17 9.5 Pushover Methods In the general case, determination of the performance point requires a trial and error search. There are three different procedures that standardize and simplify this iterative process. These alternate procedures are all based on the same concepts and mathematical relationships but vary in their dependence on analytical versus graphical techniques. These procedures are following below: 1. Procedure A Procedure A is truly iterative, but is formula based and easily can be programmed into a spreadsheet. It is more an analytical method than a graphical method. It may be the best method for beginners because it is the most direct application of the methodology, and consequently is the easiest procedure to understand. 2. Procedure B Simplification is introduced in the bilinear modeling of the capacity curve that enables a relatively direct solution for the performance point with little iteration. Like procedure A, procedure B is more an analytical method than a graphical method. Procedure B may be a less transparent application of the methodology than procedure A. 3. Procedure C Procedure C is a pure graphical method to find the performance point, similar to the originally conceived capacity spectrum method, and is consistent with the concepts and mathematical relationships. It is the most convenient method for hand analysis. It is not particularly convenient for spreadsheet programming. It is the least transparent application of the methodology. 10 Push Over Results 10.1 Structure with Infill X Direction Procedure A Page 17 of 29

18 Capacity Spectrum Point V d V/W MPF1 α1 Sa Sd T E E E-05 #DIV/0! E E E E E E E E E E E E Demand Spectrum T Sa/g Sd [sec] [m/s 2 ] [m] Page 18 of 29

19 ay = 0.59 dy = a = d = o = = 1 eff = SR A = SR V = According to graph above, performance point is at intersection point which is: a = m/s 2 d = m Page 19 of 29

20 Procedure B d a βef f S a /g βo b eff SRA SRV Sa Ts Sd % 10% 15% 20% T Sd Sa/g T Sd Sa/g T Sd Sa/g T Sd Sa/g Page 20 of 29

21 T Sd Sa/g T Sd Sa/g T Sd Sa/g T Sd Sa/g T Sd Sa/g T Sd Sa/g Page 21 of 29

22 According to graph above, performance point is at intersection point which is: a = m/s 2 d = m Page 22 of 29

23 Y Direction Procedure A ay = 0.6 dy = a = d = βo = κ = 1 βef f = SR A = SR V = Page 23 of 29

24 Procedure B According to graph above, performance point is at intersection point which is: a = m/s 2 d = m Page 24 of 29

25 10.2 Structure without Infill X Direction Procedure A ay = 0.57 dy = a = d = βo = κ = 1 βef f = SR A = SR V = Page 25 of 29

26 Procedure B According to graph above, performance point is at intersection point which is: a = m/s 2 d = m Page 26 of 29

27 Y Direction Procedure A ay = 0.58 dy = a = d = βo = κ = 1 βef f = SR A = SR V = Page 27 of 29

28 Procedure B According to graph above, performance point is at intersection point which is: a = m/s 2 d = m Page 28 of 29

29 11. Conclusions 1. According to the all pushover results above, we could conclude and compare all the performance points for each condition as following below: Performance Point For All Possibilities X Direction with infill Y Direction with infill X Direction without infill Y Direction without infill Etabs Procedure A Procedure B Expected Error a d a d a d Etabs and Proc A Etabs and Proc B [m/s 2 ] [m] [m/s 2 ] [m] [m/s 2 ] [m] a d a d % 0.00% 2.20% 0.10% % 0.11% 3.20% 0.30% % 0.20% 5.40% 0.20% % 1.06% 0.70% 0.10% It can be clearly seen that the error margin between Etabs and manual calculation are nearly similar which is interpreted by error estimation value. According to the regulation, the tolerance criterion is more less 5% than the exact result. 2. Before working the pushover by ETABS, we should calibrate the response spectra which are generated by MATLAB and ETABS. The response spectra graphs should be nearly similar between each others. It can be done by modifying the material properties or stiffness of the structures in the ETABS. 3. Procedure B is relatively more accurate than the procedure A even though it will speed a lot of time than the procedure A. 4. Procedure C is recommended to be calculated as an additional comparison of the performance point results. 5. According to the period table above, the structure with infill is much rigid than the structure without infill. Page 29 of 29