chap01 - Bauhaus - Universität Weimar, Prof....

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Unformatted text preview: Bauhaus - Universität Weimar, Prof. Bodenmechanik, Dr.-Ing. H.-G. Schmidt Content of lecture „Soil Dynamics“ (Master course: 2 Semester) 1. Introduction in the fundamentals of the soil dynamics and dynamic loads (traffic, earthquake etc.) 2. Classification and description of mechanical vibrations Description in time- and frequency domain 3. Vibration of systems Models, equations of motions, solutions in the time- and frequency domain 4. Linear single degree of freedom lumped mass systems (linear SDOF) free and forced vibrations, response spectra, eigenvalues, modal analysis 5. Linear multi degree of freedom lumped mass systems forced vibrations, eigenvalues, modal analysis 6. Wave propagation in the soil - Free vibration of the layered halfspace 3D-,2D-,1D- propagation of body waves, Amplification and filtering processes, surface waves, amplification functions 7. Dynamical behaviour of materials, dynamical soil parameter Elasticity, Damping, Stiffness, nonlinearities, experimental evaluations 8. Forced vibrations of the halfspace Models, Block vibrations, Impedance’s, examples 9. Dynamical soil-structure-interaction Modelling, Substructure method, examples 10. Design of the machine foundations Modelling, dynamic loads, eigenvalues, tuning of the frequencies, analysis of dynamic response, calculations of block foundations 11. Geotechnical earthquake engineering Natural seismicity Intensities, geoseismical effects and damages, site dependent influences: filtering and amplifications, Microzonation, Design of buildings and foundations, repair and strengthening measures, geotechnical investigations Effects of mining on surface and buildings (regular, iirregular, seismic); Building design and special measures for the foundations, repair measures 12. Shock vibrations on buildings and people measurements and evatuations, measures for mitigation / reduction Bauhaus-Universität Weimar, Prof. Bodenmechanik, Dr. H.-G. Schmidt 1.1 1. Introduction in soil dynamics and dynamic loadings 1.1 Overview, problems 1.1.1 Dynamic loadings Machines in Buildings Ship´s propeller water waves Air pressure of a bomb explosion Earthquakes 1 Time history Typical dynamic loads (a) harmonic (b) periodic (c) impuls load (d) stochastic Example Bauhaus-Universität Weimar, Prof. Bodenmechanik, Dr. H.-G. Schmidt 1.2 1.1.2 General problems a) Prevention of resonances Þ Classical field: tuning of frequencies of machine foundations b) Computation of the dynamic response of structures: dynamic induced additional stresses in the structures in connection with the kind of dynamic loads, the dynamic characteristic of the structure in interaction with the ground c) Evaluation of the stability of structures under the action of static and dynamic loadings: internal and external stability Þ Difficult: material parameter under cyclic and dyanmic loads d) Decrease / defence of damaging vebrations due to traffic, machines, constructions works Þ Mitigation / protection with measures in buildings (basic isolations) Þ geotechnical measures (improveing of the damping behaviour of the soil due to material reduction in the soil by means of slots and borings and infill of isolation material) e) Upgrading and actualisation of codes Þ DIN 4149 / EC 8 – Earthquake engineering DIN 4150 – damaging vibration on building and people Þ Harmonisation of the measures for earthquake resistant constructions f) Evaluation of construction sites using seismic methods; Geotomography, Crosshole – Measurements and Geotomography – Simultaneous measurements of wave velocities with many geophones under using of a deep varying source (SPT – Sonde) Bauhaus-Universität Weimar, Prof. Bodenmechanik, Dr. H.-G. Schmidt 1.3 1.1.3 Problems in earthquake engineering a) Influences of the extent of damages by earthquakes Natur Zivilisation Mensch · Seismology · Soil resonance · Amplifications of amplitudes · Cracks, fissures · Land slides · liquefactions · Tsunamis · · · · · · · · precaution measures · misunderstandings of the people · Catastrophe protection · Emergency plans · Social factors · Public Media Living conditions Quality of structures Building Conditions Fire protection Regional planing Infrastructure b) Analysis of the damaged regions Þ Control of the social aspects during an earthquake (information of the people, training’s, emergency plans, evacuation measures, housing problems Þ Damage analyses, documentation’s and tools for the evaluation and interpretation , Interpretation Þ Analysis of the constructions for repair and strengthening of damaged buildings Þ important: Decision tools for the elimination of damaged buildings c) Development of suffices knowledge to the load conditions Þ Earthquake loads: regional relevant time histories, frequency contents, amplitudes connect6ing with the return period of the earthquakes Þ Site effects on the earthquake excitation Þ In this point of view we need an earthquake adequate design and calculation of the buildings and geotechnical constructions / Lifelines d) Mitigation of the effects of natural disasters Þ IDNDR - International Decade of Natural Disaster Reduction 19901999 Þ New since 2000: ISDR – International Strategy for Disaster Reduction und “Inter Agency Task Forces” Þ Þ Risk evaluation: GIS – orientated analyses for damaged regions and megacities Interdisciplinary cooperation necessary with geophysics, geologists, engineers, regional planners Bauhaus-Universität Weimar, Prof. Bodenmechanik, Dr. H.-G. Schmidt 1.4 1.1.4 Evaluation of the regional losses due to an earthquake ( nach: GIS map overlay methology for regional earthquake loss estimation; Stanford University: http://blume.stanford.edu) Bauhaus-Universität Weimar, Prof. Bodenmechanik, Dr. H.-G. Schmidt 1.5 1.2 Soil Dynamics: Position in the Structural Mechanics und goals Physics Mechanic Optics Structural Mechanics – Soil Mechanics Mechanics of rigid bodies Mechanics of rigid, but deformable bodies Free of forces deformation Load dependent deformation Kinematics Dynamics – Soil Dynamics Strength of materials constant velocity variable velocity (Statics) (Kinetics) >>> in recent calculation methods (f.e. FEM) we don’t have a subdivision in the mechanics of rigid bodies and in the strength of materials Bauhaus-Universität Weimar, Prof. Bodenmechanik, Dr. H.-G. Schmidt 1.6 Tasks of the Soil dynamics Formulation of the wave propagation through the ground Description of the wave transport between soil and building Soil Parameters - Density Analysis of the time dependent stress-strain conditions in the soil Analysis of the free field - calculation of the time dependent stresses and strains in the soil - Amplification and filter effects - Liquefaction - Slope stability - Site effects – site dependent response spectra Analysis of the dynamic soil-structure-interaction - calculation of the time dependent stresses and strains in the buildingsoil-system - Influence of the Soil on the eigenfrequencies of the building - Calculation of the impedances (springs and dashpots in the interaction zone soil – foundation) - dynamic soil parameter - Damping behaviour of the soil - soil profil and ground water level - wave velocity profile in the layered halfspace Bauhaus-Universität Weimar, Prof. Bodenmechanik 1.7 DIN´s in der Dynamik DIN 1311: Schwingungslehre (1974) Blatt 1: Kinematische Begriffe Blatt 2: Einfache Schwinger Blatt 3: Schwingungssysteme mit unendlich vielen Freiheitsgraden Blatt 4: Schwingende Kontinua, Wellen DIN 1311 – 1: Schwingungen(Entwurf Oktober 1994) Teil 1: Schwingungsfähige Systeme: Begriffe, Einteilungen Teil 3: Lineare, zeitinvariante schwingungsfähige Systeme mit endlich vielen Freiheitsgraden DIN ISO 1940: Mechanische Schwingungen Anforderungen an die Auswuchtgüte starrer Rotoren Teil 1: Bestimmung der Restunwucht (Dez. 1993, identisch 1986) Teil 2: Abweichungen beim Auswuchten (Okt. 94, identisch 1993) VDI 2056: Beurteilungsmaßstäbe für mechanische Schwingungen von Maschinen (1964) VDI 2057: Einwirkung mechnischer Schwingungen auf den Menschen(Mai 1987) Blatt 1: Grundlagen, Gliederung, Begriffe Blatt 2: Bewertung Blatt 3: Beurteilung Blatt 4.1: Messung und Beurteilung von Arbeitsplätzen in Gebäuden Blatt 4.2: Messung und Beurteilung von Arbeitsplätzen auf Landfahrzeugen VDI 2062: Schwingungsisolierung (Jan. 1976) Blatt 1: Begriffe und Methoden VDI 3831: Schutzmaßnahmen gegen die Einwirkung mechanischer Schwingungen auf den Menschen – Allgemeine Schutzmaßnahmen und Beispiele DIN 4024: Maschinenfundamente (April 1988) Teil 1: Elastische Stützkonstruktionen für Maschinen mit rotierenden Massen DIN 4025: Fundamente für Amboßhämmer (Schabotte – Hämmer) (Okt. 1958) Hinweise für die Bemessung und Ausführung DIN 4149: Bauten in deutschen Erdbebengebieten (in Überarbeitung) DIN 4150: Erschütterungen im Bauwesen Teil 1: Grundsätze , Vorermittlungen und Messungen (Sept. 1975) Teil 2: Einwirkungen auf Menschen in Gebäuden(Dezember 1992) Teil 2–A/1: Änderung A1 zu Teil 2 (Entwurf Aug. 1995) Teil 3: Einwirkungen auf bauliche Anlagen (Mai 1986) DIN 4178: Glockentürme – Berechnung und Ausführung (August 1978) BU Weimar, Prof. Bodendynamik 1.8 Literature 1. Clough / Penzien: Dynamics of structures McGraw-Hill Book Company: NY – Toronto 2. Das,B.N.: Fundamentals of soil dynamics Elsevier: New York 1983 3. Haupt,W.: Bodendynamik Vieweg & Sohn: Braunschweig / Wiesbaden 1986 4. Müller / Keintzel: Erdbebensicherheit von Bauwerken W. Ernst & Sohn: Berlin 1978 5. Prakash,S.: Soil dynamics McGraw-Hill Book Company 1981 6. Richart,F.E., Hall,J.R., Woods,R.D.: Vibrations of soil and foundations Prentice-Hall, Inc. Englewood Cliffs: New Jersey 1968 7. Studer,J., Ziegler,A.: Bodendynamik Springer-Verlag: Berlin-Heidelberg-New York-Tokio 1986 8. Wolf,J.P.: Soil – Structure - Interaction Prentice-Hall, Inc. Englewood Cliffs: New Jersey 1985 9. Handbuch zur Erkundung des Untergrundes von Deponien und Altlasten, Band 3 Knödel,K; Krummel,H.;Lange,G.: Geophysik, Kap.7: Seismik Springer Berlin 1997 ...
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