Damage potential of seismic ground motion considering local site effects Schadenspotential seismischer Bodenbewegung unter Berücksichtigung lokaler Standorteffekte Dissertation zur Erlangung des akademischen Grades Doktor-Ingenieur an der Fakultät Bauingenieurwesen der Bauhaus-Universität Weimar vorgelegt von Dipl.-Ing. Dominik H. Lang aus Leonberg/Baden-Württemberg Weimar 2004 Gutachter: 1. Dr.-Ing. J. Schwarz 2. Prof. Dr.-Ing. habil. C. Könke 3. Prof. Dr. P. Gülkan Tag der Disputation: 08. Juli 2004 Acknowledgments This work came to fruition during my Ph.D. studies and scientific research at the Institute of Structural Engineering, Bauhaus-University Weimar. It was made possible by a graduation grant founded by “Vereinigung Deutscher Elektrizitätswerke -VDEW- e.V.”. The provision of this opportunity was supported by Prof. Dr.-Ing. habil. Erich Raue (Bauhaus-Universität Weimar) and Dipl.-Ing. Manfred Alt on behalf of the VDEW. For the preparation of the thesis’ survey and for useful suggestions I thank Prof. Dr.-Ing. habil Carsten Könke (Bauhaus-Universität Weimar) and Prof. Dr. Polat Gülkan (Orta Doğu Teknik Üniversitesi Ankara). I would like to express my extreme gratitude to my supervisor, Dr.-Ing. Jochen Schwarz, for the initiation of this work, his professional encouragement, and especially for his personal support. Thanks also to my colleagues of Earthquake Damage Analysis Center (EDAC), Clemens Ende and Askin Gümüs for helping me during the field works, and to Manfred Brunner for his ingenious technical solutions. Field missions of German TaskForce for Earthquakes gave me the opportunity to collect immense amounts of data, which provides the main basis for this work. Missions of German TaskForce for Earthquakes are sponsored by Hannover Rückversicherungs AG Eisen und Stahl (Hannover Re), GeoForschungsZentrum Potsdam (GFZ Potsdam), and Earthquake Damage Analysis Center at Bauhaus-University Weimar (EDAC). For their understanding, personal support, and motivation during the last years, I would also like to express my sincere thanks to my dear mother and my companion Heidi. Table of contents 1 Introduction.......................................................................................................................1 1.1 Influence of local site effects on structural damage........................................................1 1.2 Current state of research .................................................................................................3 1.3 Strategy and objective.....................................................................................................5 1.4 Applied database.............................................................................................................6 2 Seismic ground motion data.............................................................................................9 2.1 Ambient seismic noise (microtremors)...........................................................................9 2.1.1 Terms and descriptions ...........................................................................................9 2.1.2 Influencing parameters..........................................................................................10 2.1.3 Practical application..............................................................................................12 2.2 Weak and strong motion data of earthquakes...............................................................15 2.2.1 Earthquakes and seismic waves............................................................................15 2.2.2 Earthquake ground motion....................................................................................17 2.2.3 Frequency characteristics of earthquake ground motion ......................................19 2.2.3.1 The impact of magnitude, M.............................................................................19 2.2.3.2 The impact of seismic source distance, d..........................................................21 2.2.3.3 Predominant frequency of earthquake ground motion, fg .................................22 2.3 Applicability of seismic ground motion data................................................................24 2.4 Available database and seismic recording stations.......................................................25 3 Amplification potential of local subsoil.........................................................................27 3.1 Transfer characteristics of local subsoil........................................................................27 3.1.1 Soil-describing parameters....................................................................................28 3.1.2 Model-based characterization ...............................................................................30 3.1.3 Influencing effects ................................................................................................31 3.1.3.1 Presence of sedimentary soil layer(s) ...............................................................31 3.1.3.2 Nonlinear behavior of soft soils........................................................................33 3.1.3.3 Surface and subsurface topography ..................................................................37 3.2 Analytical methods (theoretical)...................................................................................40 3.2.1 Theoretical transfer function of one-dimensional subsoil profiles .......................40 3.2.2 Theoretical H/V-ratio of Rayleigh waves.............................................................42 3.3 Instrumental methods (experimental, empirical) ..........................................................46 3.3.1 Spectral amplification function method (Sa/a) on earthquake data ...................... 46 3.3.2 Fourier amplitude spectra method (FAS) on microtremor data ........................... 49 3.3.3 Standard spectral ratio method (sediment-rock spectral ratio SRSR).................. 52 3.3.3.1 Application of SRSR to earthquake data.......................................................... 52 3.3.3.2 Application of SRSR to microtremor data ....................................................... 57 3.3.4 Horizontal to vertical spectral ratio method (H/V) .............................................. 58 3.3.4.1 Application of H/V-method to microtremor data (HVNR).............................. 58 3.3.4.2 Application of H/V-method to earthquake data (HVSR)................................. 64 3.3.5 Surface-borehole spectral ratio method (SBSR) on earthquake data................... 71 3.4 Evaluation of the different site response estimation techniques .................................. 72 4 Experimental seismic site classification........................................................................ 77 4.1 Purpose of site classification ........................................................................................ 77 4.2 Site classification schemes ........................................................................................... 78 4.2.1 Stiffness-related classification schemes ............................................................... 79 4.2.2 Stiffness-and-depth-related classification schemes.............................................. 81 4.2.3 Hybrid site classification schemes ....................................................................... 83 4.3 MESSIAS - Method of an Experimental Seismic Site Assessment.................................. 84 4.3.1 Site classification procedure................................................................................. 86 4.3.2 MESSIAS ’ significance in an engineering analysis of structural damage.............. 90 5 Structural damage and site-dependent seismic action................................................ 93 5.1 Interpretation procedure of structural earthquake damage........................................... 93 5.1.1 Observations of earthquake-induced effects in regions of high seismicity.......... 93 5.1.2 Procedure and basic principles............................................................................. 94 5.1.3 Selected damage cases for further investigations................................................. 98 5.2 Structural performance under dynamic excitation ..................................................... 103 5.2.1 Structural modeling ............................................................................................ 103 5.2.1.1 Regulations and modeling rules ..................................................................... 103 5.2.1.2 Experimental identification of the dynamic building characteristics............. 104 5.2.1.3 Calibration of the structural model................................................................. 108 5.2.2 Nonlinear static “pushover” analysis ................................................................. 110 5.2.2.1 Structural capacity.......................................................................................... 110 5.2.2.2 Seismic demand.............................................................................................. 112 5.3 Specification of the seismic demand.......................................................................... 114 5.3.1 Identification of local subsoil conditions ........................................................... 115 5.3.2 Damage-inducing demand level......................................................................... 116 5.3.2.1 Recordings of earthquake ground motion .....................................................