# Parametric Studies of Source and Site Effects for the Generation of

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Parametric Studies of Source and Site Effects for the Generation of

Workshop Workshop on on seismic seismic input input motions, motions, incorporating incorporating recent recent geological geological studies studies Tsukuba, Tsukuba, Japan Japan 15 15 November November 2004 2004 Parametric Parametric Studies Studies of of Source Source and and Site Site Effects Effects for for the the Generation Generation of of Groundshaking Groundshaking Scenarios Scenarios Fabio Fabio ROMANELLI ROMANELLI Dept. Dept.Earth EarthSciences Sciences Università Universitàdegli deglistudi studididiTrieste Trieste Franco Franco VACCARI VACCARI Giuliano Giuliano F. F. PANZA PANZA SAND SAND GROUP GROUP of ofthe theabdus abdus salam salam international centre for theoretical international centre for theoreticalphysics physics Outline Introduction Some problems in SHA (source-site effects) P-B design input Realistic definition of seismic input Example Case and parametric studies Focal mechanism Site effects Directivity Conclusions PSHA PSHA & & DSHA DSHA dualism dualism PSHA Waveform modelling Accounts for all potentially damaging earthquakes in a region Focus on selected controlling earthquakes Single parameter Complete time series Deeply rooted in engineering practice (e.g. buliding codes) Dynamic analyses of critical facilities Disaggregation, recursive analysis Introduction Study of attenuation relationships PSHA DSHA PEER Report Introduction In many applications a recursive analysis, where deterministic interpretations are triggered by probabilistic results and vice versa, will give the greatest insight and allow the most informed decisions to be made. Important Important issues issues in in SRE SRE Modified from: Field et al., 2000 Near surface effects: impedance contrast, velocity geological maps, v30, vl/4, ?? Basin effects Basin-edge induced waves Subsurface focusing The convolutional model is ultimately artificial (e.g. fault rupturing along the edge of a deep basin) Problems in SHA-Site effects SRE SRE and and SHA SHA Amplification patterns may vary greatly among the earthquake scenarios, considering different source locations (and rupture ...) SCEC Phase 3 Report The convolutional model is ultimately artificial (e.g. fault rupturing along the edge of a deep basin) Problems in SHA-Site effects SRE SRE and and SHA SHA In SHA the site effect should be defined as the average behavior, relative to other sites, given all potentially damaging earthquakes This produces an intrinsic variability with respect to different earthquake locations, that cannot exceed the difference between sites Site characterization: which velocity? use of basin depth effect? Is it a proxy for backazimuth distance? how to reduce aleatoric uncertainty? Problems in SHA-Site effects Seismic Seismic Input Input A proper definition of the seismic input for PBD at a given site can be done following two main approaches: The first approach is based on the analysis of the available strong motion databases, collected by existing seismic networks, and on the grouping of those accelerograms that contain similar source, path and site effects The second approach is based on modelling techniques, developed from the knowledge of the seismic source process and of the propagation of seismic waves, that can realistically simulate the ground motion The The ideal ideal procedure procedure is is to to follow follow the the two two complementary complementary ways, ways, in in order order to to validate validate the the numerical numerical modelling modelling with with the the available available recordings recordings Definition of seismic input Validation Validation The ideal procedure is to follow the two complementary ways, in order to validate the numerical modelling with the available recordings (e.g. Decanini et al., 1999; Panza et al., 2000a,b,c). Validation and calibration should consider intensity measures (PGA, PGV, PGD, SA, etc.) as well as other characteristics (e.g. duration). The misfits can be due to variability in the physical (e.g. point-source) and/or the parameters models adopted. Definition of seismic input Prediction Prediction The result of a simulation procedure should be a set of intensity estimates, as the result of a parametric study for different “events” and/or for different model parameters The modeling variability, estimated through validation, can be associated to “models” or “parameters” Epistemic Modeling (point source, 1D-2D-3D) Parametric (incomplete data) Aleatory Modeling (scattering, rupture) Parametric (rupture) e.g. Stewart et al., 2001 Definition of seismic input Time Time histories histories selection selection They They are are used used to to extract extract aa measure, measure, representing representing adequately: adequately: Magnitude, Magnitude, distance distance Source Source characteristics characteristics (fling, (fling, directivity) directivity) Path Path effects effects (attenuation, (attenuation, regional regional heterogeneities) heterogeneities) Site Site effects effects (amplification, (amplification, duration) duration) The The groundshaking groundshaking scenarios scenarios have have to to be be based based on on significant significant ground ground motion motion parameters parameters (e.g. (e.g. velocity velocity and and displacement). displacement). Definition of seismic input Parameters Parameters extraction extraction Particularly, in the case of forward rupture directivity most of the energy arrives in a single large pulse of motion which may give rise to particularly severe ground motion at sites toward which the fracture propagation progresses. it involves the transmission of large energy amounts to the structures in a very short time. These shaking descriptors, strictly linked with energy demands, are relevant (even more than acceleration), especially when dealing with seismic isolation and passive energy dissipation in buildings. Performance-Based Design VAB VAB Project Project (EC) (EC) ADVANCED ADVANCED METHODS METHODS FOR FOR ASSESSING ASSESSING THE THE SEISMIC SEISMIC VULNERABILITY VULNERABILITY OF OF EXISTING EXISTING MOTORWAY MOTORWAY BRIDGES BRIDGES ARSENAL RESEARCH, Vienna, Austria; ISMES S.P.A,. Bergamo, Italy; ICTP, Trieste, Italy; UPORTO, Porto, Portugal; CIMNE, Barcelona, Spain; SETRA, Bagneaux, France; JRC-ISPRA, EU. Effects on bridge seismic response of asynchronous motion at the base of bridge piers Examples Examples from from EU EU project project Databank of geological, geophysical and seismotectonic data SEISMIC SOURCES 1) Database of focal mechanism 9 10 11 12 13 14 15 16 17 SEM63 SEM64_2 49 49 48 48 WARTH SEM64_1 47 47 SEE72 NEU72 46 46 9 10 11 12 13 14 15 16 17 2) Parametric study on focal mechanism: strike dip rake depth Maximum Credible Earthquake Maximum Design Earthquake Case study examples Maximum Historical Earthquake Initial LHM - Warth bridge - model S-wave velocities Case study examples 120 220 290 (m/s) 1100 1800 1900 Bedrock Initial Initial regional regional model model EUR EUR II data data set set Density (g/cm3) Distance (km) 300 0 0 Depth (km) 50 Depth (km) 100 150 200 250 300 2 3 4 5 6 7 8 9 10 1 2 3 4 Attenuation 5 0 500 1000 0 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 350 1 2 3 4 5 6 7 8 Velocity (km/s) 400 1.0 2.5 3.0 3.5 4.0 4.2 4.5 S-wave velocity (km/s) Definition of str. models 4.8 5.0 5.5 1500 0 9 10 1 2 3 Density 4 (g/cm3) 5 0 500 1000 Attenuation 100 1500 Depth (km) Velocity (km/s) 1 Hybrid Hybrid method: method: MS-FD MS-FD Distance from the source Free surface A Depth Source Reference layered model Artificial boundaries, limiting the FD grid. A Zone of high attenuation, where Q is decreasing linearly toward the artificial boundary. Local heterogeneous model Definition of seismic input Adjacent grid lines, where the wave field is introduced into the FD grid. The incoming wave field is computed with the mode summation technique. The two grid lines are transparent for backscattered waves (Alterman and Karal, 1968). Site Different source-section configurations S3 S2 S1 Bedrock model S3 Mw = 6.0 Distance = 50 km Definition of seismic input S1 Strike = 190˚ Dip = 70˚ Rake = 324˚ Depth = 5 km Mw = 5.5 Distance = 8.7 km S2 Mw = 5.5 Distance = reverse COMPUTATION COMPUTATION OF OF SEISMIC SEISMIC INPUT INPUT PRELIMINARY COMPUTATION INITIAL source and structural models 3 components of motion Displacement, velocity, acceleration FINAL COMPUTATION FINAL source and structural models 3 components of motion Displacement, velocity, acceleration SEISMIC INPUT DIFFERENTIAL MOTION SITE RESPONSE 1) 1D 10 Hz Parametric study 2) 2D 8Hz 1) time domain 2) spectral domain 1) Fourier spectral ratios 2) Response spectral ratios Case study examples PARAMETRIC PARAMETRIC STUDY STUDY -- Fp Fp towards towards MCE MCE All the focal mechanism parameters of the original source model have been varied in order to find the combination producing the maximum amplitude of the various ground motion components. 0° 0° 330° 20 30° 300° 330° 30° 300° 60° 60° source depth (km) 1000 900 270° 90° 90° 270° 1) Strike 150 100 50 (Depth=5km) 0 10 8 6 4 2 0 15 250 200angle 800 700 120° 240° 120° 2) Rake240°angle 600 210° 150° 210° 150° 10 a) 180° 180° b) 3) Strike-Rake angles variation (Dip=45°) 500 0° 400 330° 30° 300 4) Strike-Rake angles variation (Dip=70°) 300° 60° 5 200 5) Strike-Rake angles variation (Dip=90°) 100 270° 90° 1 0.8 0.6 0.4 0.2 0 6) Depth-Distance variation 0 5 (Strike=60°, 240° 10 15 210° distance (km) 150° Dip=70°,Rake=0, c) 180° 0 120° 20 90°) The computations of synthetic seismograms (displacements, velocities and accelerations for the radial, transverse and vertical components) have been carried out with cut-off frequency 10 Hz. Parametric study 1 - FP cm/s**2 Tranverse Tranverse accelerograms accelerograms M=5.5, M=5.5, d=6km d=6km 400 200 0 -200 -400 0 1 2 200 250 260 290 300 400 500 1000 1100 1900 Bedrock Parametric study 1 - FP 3 4 5 6 time (s) 7 8 9 10 Tranverse Tranverse acceleration acceleration spectra spectra 300 first_2 Acceleration FA (cm/s) 100 0 1 2 3 4 5 6 7 frequency (Hz) 8 9 10 300 prev_5 200 first_5 100 prev_7 200 100 0 0 0 fsp_3 first_7 1 2 3 4 5 6 7 frequency (Hz) 8 0 9 10 1 2 3 4 5 6 7 frequency (Hz) 8 9 10 prev_3 200 300 first_3 fsp_8 300 0 0 1 2 3 4 5 6 7 frequency (Hz) 8 9 10 300 prev_4 200 fsp_6 first_4 Acceleration FA (cm/s) 100 Acceleration FA (cm/s) fsp_4 Acceleration FA (cm/s) 0 fsp_7 fsp_5 Acceleration FA (cm/s) 200 300 300 prev_2 Acceleration FA (cm/s) Acceleration FA (cm/s) fsp_2 100 prev_6 200 first_6 1 2 3 4 5 6 7 frequency (Hz) 8 0 0 Parametric study 1 - FP 100 0 9 10 0 200 250 260 290 300 400 500 1000 1100 1900 Bedrock first_8 200 100 0 0 prev_8 1 2 3 4 5 6 7 frequency (Hz) 8 9 10 1 2 3 4 5 6 7 frequency (Hz) 8 9 10 PARAMETRIC PARAMETRIC STUDY STUDY 22 -- Fp Fp towards towards 1Hz 1Hz Another parametric study has been performed in order to find a seismic sourceWarth site configuration providing a set of signals whose seismic energy is concentrated around 1 Hz, frequency that corresponds approximately to that of the fundamental transverse mode of oscillation of the bridge. 20 1.2 500 1.15 450 16 1.1 400 14 1.05 350 1 300 0.95 250 0.9 200 0.85 150 0.8 100 focal depth (km) 18 12 10 8 6 4 0 10 20 30 50 40 60 source-site distance (km) 70 80 90 100 The The results results show show that, that, in in order order to to reach reach aa relevant relevant value value of of PGA PGA (e.g. (e.g. greater greater than than 0.1g) 0.1g) in in the the desired desired period period range range (i.e. (i.e. 0.8-1.2 0.8-1.2 s), s), an an alternative alternative and and suitable suitable configuration configuration is is aa source source 12 12 km km deep deep at at an an epicentral epicentral distance distance of of 30 30 km. km. Parametric Parametric study study 22 -- FS FS & & RSR RSR 1 70 70 2 60 60 3 50 50 4 40 40 5 Acceleration FA (cm/s) Acceleration FA (cm/s) 80 80 6 30 30 7 20 20 0 0 2 3 4 5 6 7 8 8 bedrock bedrock 10 10 0 1 0 1 1 2 2 3 3 4 5 6 4 5 6 frequency (Hz) frequency (Hz) 7 7 8 8 9 9 10 10 8.0 8.0 3.5 3.5 7.0 7.0 3.0 3.0 6.0 6.0 2.5 2.5 4.0 4.0 2.0 2.0 Frequency (Hz) Frequency (Hz) 5.0 5.0 3.0 3.0 1.5 1.5 2.0 2.0 1.0 1.0 1.0 1.0 0.0 0.0 30.0 30.0 0.5 0.5 30.1 30.1 30.2 30.2 30.3 30.4 30.3 30.4 Distance (km) Distance (km) 30.5 30.5 30.6 30.6 30.7 30.7 The The results results show show that, that, the the local local structure structure beneath beneath the the Warth Warth bridge bridge greatly greatly amplifies amplifies the the frequency frequency components components between between 33 and and 77 Hz, Hz, i.e. i.e. aa frequency frequency range range not not corresponding corresponding to to the the fundamental fundamental transverse transverse mode mode of of oscillation oscillation of of the the bridge bridge (about (about 0.8 0.8 Hz) Hz) Parametric study 2 - DD Parametric Parametric study study 33 -- LMp LMp towards towards 1Hz 1Hz a) Local geotechnical models of Warth bridge section obtained lowering successively the S-wave velocities of the uppermost units b) c) 100 125 Parametric study 3 - LM 130 140 150 S wave velocities (m/s) 200 250 1000 Bedrock 1900 1100 400 400 SS1a_1 SS1a_1 SS1a_2 SS1a_2 350 350 AccelerationFA FA(cm/s) (cm/s) Acceleration 300 300 Parametric Parametric study study 33 FAS FAS SS1a_3 SS1a_3 SS1a_4 SS1a_4 250 250 SS1a_5 SS1a_5 SS1a_6 SS1a_6 200 200 150 150 SS1a_7 SS1a_7 SS1a_8 SS1a_8 100 100 50 50 11 22 33 44 55 66 frequency (Hz) frequency (Hz) 77 88 99 10 10 SS1b_1 SS1b_1 SS1b_2 SS1b_2 350 350 AccelerationFA FA(cm/s) (cm/s) Acceleration 300 300 300 300 150 150 200 200 50 50 00 00 400 400 00 00 400 400 33 44 55 66 frequency frequency(Hz) (Hz) 77 88 10 10 SS1c_1 SS1c_1 SS1c_2 SS1c_2 350 350 AccelerationFA FA(cm/s) (cm/s) Acceleration 300 300 200 200 50 50 11 22 Case study examples 33 44 55 66 frequency (Hz) frequency (Hz) 77 88 99 33 44 55 66 frequency (Hz) frequency (Hz) 77 10 10 SS2c_5 SS2c_5 SS2c_6 SS2c_6 150 150 SS2c_7 SS2c_7 SS2c_8 SS2c_8 100 100 50 50 00 00 99 SS2c_3 SS2c_3 SS2c_4 SS2c_4 200 200 10 10 88 SS2c_1 SS2c_1 SS2c_2 SS2c_2 250 250 SS1c_7 SS1c_7 SS1c_8 SS1c_8 100 100 22 300 300 SS1c_5 SS1c_5 SS1c_6 SS1c_6 150 150 11 350 350 SS1c_3 SS1c_3 SS1c_4 SS1c_4 250 250 00 00 99 AccelerationFA FA(cm/s) (cm/s) Acceleration 22 SS2b_7 SS2b_7 SS2b_8 SS2b_8 100 100 50 50 11 SS2b_5 SS2b_5 SS2b_6 SS2b_6 150 150 SS1b_7 SS1b_7 SS1b_8 SS1b_8 100 100 SS2b_3 SS2b_3 SS2b_4 SS2b_4 250 250 SS1b_5 SS1b_5 SS1b_6 SS1b_6 200 200 SS2b_1 SS2b_1 SS2b_2 SS2b_2 350 350 SS1b_3 SS1b_3 SS1b_4 SS1b_4 250 250 400 400 AccelerationFA FA(cm/s) (cm/s) Acceleration 00 00 400 400 11 22 33 44 55 66 frequency (Hz) frequency (Hz) 77 88 99 10 10 8.0 8.0 7.0 7.0 7.0 7.0 6.0 6.0 6.0 6.0 5.0 5.0 Frequency (Hz) Frequency (Hz) 5.0 5.0 4.0 4.0 4.0 4.0 3.0 3.0 3.0 3.0 2.0 2.0 2.0 2.0 1.0 1.0 1.0 1.0 0.0 0.0 8.6 8.0 8.6 8.0 Parametric Parametric study study 33 RSR RSR 0.0 0.0 8.7 8.7 8.8 8.8 8.9 9.0 9.1 8.9 9.0 9.1 Distance (km) Distance (km) 9.2 9.2 9.3 9.3 9.4 9.4 8.0 8.0 7.0 7.0 6.0 6.0 6.0 6.0 5.0 5.0 5.0 5.0 Frequency (Hz) Frequency (Hz) Frequency (Hz) Frequency (Hz) 7.0 7.0 4.0 4.0 4.0 4.0 3.0 3.0 3.0 3.0 2.0 2.0 2.0 2.0 1.0 1.0 1.0 1.0 0.0 0.0 8.6 8.0 8.6 8.0 8.7 8.7 8.8 8.8 8.9 9.0 9.1 8.9 9.0 9.1 Distance (km) Distance (km) 9.2 9.2 9.3 9.3 9.4 9.4 0.0 0.0 30.0 30.0 8.0 8.0 7.0 7.0 6.0 6.0 6.0 6.0 5.0 5.0 5.0 5.0 4.0 4.0 30.3 30.4 30.3 30.4 Distance (km) Distance (km) 30.5 30.5 30.6 30.6 30.7 30.7 30.1 30.1 30.2 30.2 30.3 30.4 30.3 30.4 Distance (km) Distance (km) 30.5 30.5 30.6 30.6 30.7 30.7 4.0 4.0 3.0 3.0 3.0 3.0 2.0 2.0 2.0 2.0 1.0 1.0 1.0 1.0 0.0 0.0 8.6 8.6 30.2 30.2 Frequency (Hz) Frequency (Hz) Frequency (Hz) Frequency (Hz) 7.0 7.0 30.1 30.1 8.7 8.7 8.8 8.8 Case study examples 8.9 9.0 9.1 8.9 9.0 9.1 Distance (km) Distance (km) 9.2 9.2 9.3 9.3 9.4 9.4 0.0 0.0 30.0 30.0 Synthetic Synthetic accelerations accelerations and and diffograms diffograms Case study examples 400 400 SS2c_1 SS2c_1 SS2c_2 SS2c_2 350 350 AccelerationFA FA(cm/s) (cm/s) Acceleration 300 300 200 200 SS2c_5 SS2c_5 SS2c_6 SS2c_6 150 150 SS2c_7 SS2c_7 SS2c_8 SS2c_8 100 100 50 50 11 22 33 44 55 66 frequency (Hz) frequency (Hz) 77 99 10 10 p_2 p_2 350 350 AmplitudeFourier FourierSpectra Spectra(cm/s) (cm/s) Amplitude 88 p_4 p_4 250 250 p_5 p_5 44 66 f_2 f_2 350 350 AmplitudeFourier FourierSpectra Spectra(cm/s) (cm/s) Amplitude 55 f_4 f_4 250 250 f_5 f_5 44 66 f_3_1D f_3_1D f_4_1D f_4_1D f_5_1D f_5_1D f_6_1D f_6_1D f_7_1D f_7_1D 150 150 f_8 f_8 55 f_2_1D f_2_1D 200 200 f_8_1D f_8_1D 100 100 100 100 50 50 00 00 400 400 33 frequency frequency(Hz) (Hz) 250 250 f_7 f_7 150 150 22 300 300 f_6 f_6 200 200 11 350 350 f_3 f_3 300 300 p_8_1D p_8_1D 50 50 00 00 AmplitudeFourier FourierSpectra Spectra(cm/s) (cm/s) Amplitude 33 frequency frequency(Hz) (Hz) p_7_1D p_7_1D 100 100 50 50 22 p_6_1D p_6_1D 150 150 p_8 p_8 11 p_5_1D p_5_1D 200 200 100 100 00 00 400 400 p_4_1D p_4_1D 250 250 p_7 p_7 150 150 p_3_1D p_3_1D 300 300 p_6 p_6 200 200 p_2_1D p_2_1D 350 350 p_3 p_3 300 300 400 400 AmplitudeFourier FourierSpectra Spectra(cm/s) (cm/s) Amplitude 00 00 400 400 Synthetic Synthetic accelerations accelerations and and diffograms diffograms FAS FAS SS2c_3 SS2c_3 SS2c_4 SS2c_4 250 250 11 Case study examples 22 33 frequency frequency(Hz) (Hz) 44 55 66 50 50 00 00 11 22 33 frequency frequency(Hz) (Hz) 44 55 66 Parametric Parametric study study -- ESp ESp towards towards directivity directivity Case study examples 2nd rupture model: unilateral at 3 positions Parametric Parametric study study -- ESp ESp towards towards directivity directivity Case study examples 2nd rupture model: unilateral at 3 positions Parametric Parametric study study -- ESp ESp towards towards directivity directivity Case study examples 3rd rupture model: different vr at 3 positions Parametric Parametric study study -- ESp ESp towards towards directivity directivity Case study examples 3rd rupture model: different vr at 3 positions Parametric Parametric study study 44 -- ESp ESp towards towards directivity directivity PGV (cm/s) PGV (cm/s) 100 100 PGV_NU PGV_NU PGV_FU PGV_FU PGV_NU_BED PGV_NU_BED PGV_FU_BED PGV_FU_BED SOM98_5.5 SOM98_5.5 AK00_5.5 AK00_5.5 RM00_5.5S RM00_5.5S 10 10 1 1 8.6 8.6 8.7 8.7 8.8 8.8 8.9 8.9 9 9 Epicentral distance (km) Epicentral distance (km) 9.1 9.1 9.2 9.2 9.3 9.3 9.4 9.4 100 100 1000 1000 PGA (cm/s**2) PGA (cm/s**2) PGV (cm/s) PGV (cm/s) PGV_NV PGV_NV PGA_NU PGV_FV PGA_NU PGV_FV PGA_FU PGV_NV_BED PGA_FU PGV_NV_BED PGA_NV PGV_FV_BED PGA_NV PGV_FV_BED PGA_FV SOM98_5.5 PGA_FV SOM98_5.5 AK00_5.5 AK00_5.5 RM00_5.5S RM00_5.5S 10 100 10 100 10 10 8.6 1 8.6 1 8.6 8.6 Parametric study 4 - ES 8.7 8.7 8.7 8.7 8.8 8.8 8.8 8.8 8.9 9 8.9 9 Epicentral distance (km) (km) 8.9 Epicentral distance 9 8.9 9 Epicentral distance (km) Epicentral distance (km) 9.1 9.1 9.1 9.1 9.2 9.2 9.2 9.2 9.3 9.3 9.3 9.3 9.4 9.4 9.4 9.4 PGV - PGA Parametric Parametric study study 44 -- ESp ESp towards towards directivity directivity 250 250 uni_1 uni_1 unv_1 unv_1 150 150 uni_2 uni_2 unv_2 unv_2 SV(cm/s) (cm/s) SV 200 200 100 100 50 50 00 00 0.5 0.5 11 1.5 1.5 22 2.5 2.5 period period(s) (s) 33 3.5 3.5 44 4.5 4.5 55 4.5 4.5 55 1600 1600 1400 1400 uni_1 uni_1 uni_2 uni_2 SA(cm/s**2) (cm/s**2) SA 1200 1200 Parametric study 4 - ES unv_1 unv_1 unv_2 unv_2 1000 1000 800 800 600 600 400 400 200 200 00 00 0.5 0.5 11 1.5 1.5 22 2.5 2.5 period period(s) (s) 33 3.5 3.5 44 response spectra Implementation Implementation of of PSD PSD tests tests (a) physical piers in the lab, (b), schematic representation (c) workstations running the PSD algorithm and controlling the test Case study examples Force-displacement for Low-level earthquake experimental results Pier A40 Identification of insufficient seismic detailing. tall pier A40, buckling of longitudinal reinforcement at h = 3.5m Damage pattern after the end of the High-Level Earthquake PSD test, short pier A70. Case study examples Conclusions Conclusions (?) (?) Case studies of seismic hazard assessment techniques indicate the limits of the currently used methodologies, deeply rooted in engineering practice, often conditioned by the definition of the seismogenic zones. Particularly important are the parameters used to characterize the damage potential of earthquake ground motion at a site. The quantification of the critical ground motion (for PBD) expected at a particular site can be identified in terms of energy and displacement demands – the latter particularly relevant for seismic isolation . Conclusions Conclusions Conclusions -- 11 Different Different ground ground motions motions at at the the Warth Warth site site have have been been studied studied in in order order to to define define the the maximum maximum excitation excitation in in longitudinal longitudinal and and transverse transverse direction, direction, which which are are consistent consistent both both with with the the Maximum Maximum Credible Credible Earthquake Earthquake and and with with the the Maximum Maximum Design. Design. The The main main practical practical conclusion conclusion of of our our analysis, analysis, verified verified by by laboratory laboratory experiments experiments carried carried out out at at JRC-ISPRA, JRC-ISPRA, is is that that the the Warth Warth bridge bridge is is likely likely to to well well stand stand the the most most severe severe seismic seismic input input compatible compatible with with the the seismic seismic regime regime of of the the Eastern Eastern Alps. Alps. With With the the parametric parametric study study we we have have defined defined aa seismic seismic sourcesourceWarth Warth site site configuration configuration that that provides provides aa set set of of signals signals whose whose seismic seismic energy energy is is concentrated concentrated around around 11 Hz, Hz, frequency frequency that that corresponds corresponds approximately approximately to to that that of of the the fundamental fundamental transverse transverse mode mode of of oscillation oscillation of of the the bridge. bridge. Conclusions Conclusions Conclusions -- 22 The The results results show show that that lateral lateral heterogeneity heterogeneity can can produce produce strong strong spatial spatial variations variations in in the the ground ground motion motion even even at at small small incremental incremental distances. distances. Such Such variations variations can can hardly hardly be be accounted accounted for for by by the the stochastic stochastic models models commonly commonly used used in in engineering engineering practice. practice. In In absolute absolute terms, terms, the the differential differential motion motion amplitude amplitude is is comparable comparable with with the the input input motion motion amplitude amplitude when when displacement, displacement, velocity velocity and and acceleration acceleration domains domains are are considered. considered. On On the the base base of of the the existing existing empirical empirical regression regression relations relations between between Intensity Intensity and and peak peak values values of of ground ground motion motion aa general general result result of of our our modeling modeling is is that that the the effect effect of of the the differential differential motion motion can can cause cause an an increment increment greater greater than than one one unit unit in in the the seismic seismic intensity intensity experienced experienced by by the the bridge, bridge, with with respect respect to to the the average average intensity intensity affecting affecting the the area area where where the the bridge bridge is is built. built. Conclusions