bluuebunny/crossref_metadata_2025_split huggingface dataset:
Das DIBt als Partner im Twinning Projekt “Umsetzung der Eurocodes in Lettland”
Authors: Lutz Holger 
Published: April 2007

AbstractUnter dem Begriff “Twinning” (engl.: to be twinned = in Partnerschaft verbunden sein) werden Partnerschaftsprojekte im Rahmen der Europäischen Union verstanden, die auf wichtigen Politikfeldern den Auf‐ und Ausbau institutioneller Strukturen in den Kandidaten‐ und neuen Mitgliedstaaten fördern sollen. Alle Beitrittswilligen haben die enorm schwierige Aufgabe, den “Acquis Communautaire”, den die “alten” Mitgliedstaaten in Jahrzehnten erworben haben, in allerkürzester Zeit auf ihrem Staatsgebiet ebenfalls zu installieren.
Non‐linear earthquake response of concrete gravity dams part 2: Behaviour
Authors: El‐Aidi Bahaa , Hall John F. 
Published: April 2007

AbstractThe earthquake response of the idealized Pine Flat Dam—water—foundation system of Part 1 is investigated with emphasis on the non‐linear behaviour associated with concrete cracking and water cavitation. It is shown that water cavitation has little effect on the dam response. On the other hand, concrete cracking plays a significant role, as demonstrated by several analyses on dams with initial cracks or weak lift joints and by a final analysis on a homogeneous dam. The analyses encountered a number of numerical difficulties requiring further mesh refinement, and these are described. A possible failure mode associated with inclined cracks is revealed.
Earthquake analysis with generalized plasticity model for saturated soils
Authors: Desai C. S. , Galagoda H. M. 
Published: April 2007

AbstractA plasticity based constitutive model for anisotropic behaviour of soils is implemented in a finite element procedure based on the generalized Biot theory for the dynamic non‐linear response of porous materials. The model represents a version in the hierarchical approach of constitutive modelling and allows for inelastic response during loading, unloading and reloading. The procedure has been verified previously with respect to closed‐form solutions for wave propagation in porous media. In this paper, it is used to predict the behaviour of a realistic structure‐saturated porous soil system subjected to earthquake loading. Both linear and non‐linear analyses have been performed. It has been found that the predicted responses from the two analyses are significantly different; for example, in comparison with the linear analysis the non‐linear response shows increased magnitudes and zones of concentration of pore water pressures, increased magnitudes of horizontal displacements, decreased magnitudes of vertical displacements and increased magnitudes of shear stresses.
Seismic response of offshore structures in random seas
Authors: Yamada Y. , Iemura H. , Kawano K. , Venkataramana K. 
Published: April 2007

AbstractA study of the dynamic response of offshore structures to simultaneous loadings by random earthquake ground motions and random sea waves is presented. Emphasis is placed on the evaluation of dynamic soil‐structure interaction effects and also on the evaluation of non‐linear hydrodynamic damping effects due to sea waves for the seismic response. The structure is discretized using the finite element method. Sea waves are represented by Bretschneider's power spectrum and the Morison equation defines the wave forcing function. The Tajimi‐Kanai power spectrum is used for the horizontal ground acceleration due to earthquakes. The governing equations of motion are obtained by the substructure method. Response analysis is carried out using the frequency‐domain random vibration approach.It is found that the first few vibrational modes contribute significantly to the dynamic response. The response due to earthquake loadings is larger when the soil‐structure interaction effects are considered. The hydrodynamic damping forces are higher in random seas than in still water and sea waves reduce the seismic response of offshore structures. Studies on the first passage probabilities of response indicate that small sea waves enhance the reliability of offshore structures against earthquake forces.
Lanczos method for dynamic analysis of damped structural systems
Authors: Nour‐Omid B. , Regelbrugge M. E. 
Published: April 2007

AbstractIn this paper we extend the Lanczos algorithm for the dynamic analysis of structures7 to systems with general matrix coefficients. The equations of dynamic equilibrium are first transformed to a system of first order differential equations. Then the unsymmetric Lanczos method is used to generate two sets of vectors. These vectors are used in a method of weighted residuals to reduce the equations of motion to a small unsymmetric tridiagonal system.The algorithm is further simplified for systems of equations with symmetric matrices. By appropriate choice of the starting vectors we obtain an implementation of the Lanczos method that is remarkably close to that in Reference 7, but generalized to the case with indefinite matrix coefficients. This simplification eliminates one of the sets of vectors generated by the unsymmetric Lanczos method and results in a symmetric tridiagonal, but indefinite, system. We identify the difficulties that may arise when this implementation is applied to problems with symmetric indefinite matrices such as vibration of structures with velocity feedback control forces which lead to symmetric damping matrices.This approach is used to evaluate the vibration response of a damped beam problem and a space mast structure with symmetric damping matrix arising from velocity feedback control forces. In both problems, accurate solutions were obtained with as few as 20 Lanczos vectors.
Response of base‐isolated buildings to wind loading
Authors: Henderson Paul , Novak Milos 
Published: April 2007

AbstractThe response of base‐isolated buildings to gusting wind is analysed theoretically based on experimental data obtained in a boundary layer wind tunnel. A comparison is made with the response evaluated using existing codes. A special procedure, similar to that of current codes, for computing the alongwind and torsional responses of base‐isolated buildings is presented.
Optimum strong‐motion array geometry for source inversion—II
Authors: Iida Masahiro 
Published: April 2007

AbstractOptimum strong‐motion array geometry for source inversions is again determined for each of three types of earthquake faults: strike‐slip, dip‐slip and offshore subduction thrust. The method is the same as employed in a previous study;1 however, use of a complete Green's function in an elastic half‐space provides better results for engineering practice. It is found that the complete Green's function is capable of stabilizing the accuracy of an inversion solution obtained using theoretical seismograms, regardless of the differences in array configuration. The optimum strong‐motion array for a strike‐slip fault is characterized by stations well distributed in azimuth, while the optimum array for a dip‐slip event has stations arranged in a grid‐shaped form. The array geometries obtained here are grossly similar to those in the previous study,1 which were derived using only the far‐field S waves, and are more consistent with those proposed at the 1978 International Workshop on Strong‐Motion Earthquake Instrument Arrays.2.
Feasibility and robustness of predictive control of building structures by active cables
Authors: López‐Almansa F. , Rodellar J. 
Published: April 2007

AbstractIn this paper a theoretical and numerical analysis on the robustness and the practical feasibility of a control system of an experimental model of a building structure is performed. This model has a mechanical actuator employing active cables and the control algorithm is based on a predictive strategy. In order to test the robustness one simulates numerically different control experiments under two kinds of non‐ideal conditions: (i) discrepancies between the parameters of the system (mass, natural frequencies and the time delay in the actuator) and those assumed in the formulation of the control algorithm; (ii) operation of the active cables out of the operation range caused by excitations stronger than expected. In order to assess the feasibility, in every control experiment one obtains the values of four performance indices which provide full information about the features of the control action. The numerical results show that predictive control by active cables is robust and feasible.
Dynamic response of multiply connected primary‐secondary systems
Authors: Muscolino Giuseppe 
Published: April 2007

AbstractA method to evaluate the dynamic response of composite multiply connected primary‐secondary systems is presented. For this purpose the nodal equations of motion of the composite system are given in ‘total’ and ‘relative’ coordinates. In the framework of the component‐mode synthesis method a coordinate transformation, here defined as an admissible one, is used to reduce the nodal equations of motion. This coordinate transformation is theoretically and numerically compared with the coordinate transformation usually used in the literature, which generally gives larger errors with respect to the former when a reduced number of nodes is considered.
Experimental behaviour of reinforced concrete walls under earthquake loading
Authors: Elnashai A. S. , Pilakoutas K. , Ambraseys N. N. 
Published: April 2007

AbstractThe experimental work and first results of a recently completed experimental research programme investigating the response of reinforced concrete (RC) walls under earthquake (EQ) loading are discussed in this paper. A brief literature review is given as a prelude to the outline of research objectives. The tests are presented in two groups according to the scale of models. For the 1:5 scale tests, a modified similitude relation for small scale reinforced concrete dynamic modelling is developed. Based on the chosen model parameters, the design of the isolated RC walls is given. The test‐rig set‐up and the EQ input signals suitable for testing the model on the Imperial College shake‐table are also discussed. Preliminary observations regarding stiffness, strength and failure modes of the RC wall models are given. Experimental results from the shake‐table are compared to tests, at the same scale, under static cyclic conditions. For the scale 1:2–5 cyclic tests a different test‐rig assembly is designed. The test results are given in three pairs of flexurally similar walls followed with general observations and discussion. Finally, conclusions are drawn regarding experimental procedures and behaviour patterns of the tested models.
Non‐linear steady state vibration and dynamic snap through of shallow arch beams
Authors: Leung A. Y. T. , Fung T. C. 
Published: April 2007

AbstractThe non‐linear steady state vibration of shallow arch beams is studied by a finite element method based on the principle of virtual work. Both the free and forced periodic vibrations are considered. The axial and flexural deformations are coupled by the induced axial force along the beam element. The spatial discretization is achieved by the usual finite element method and the steady state nodal displacements are expanded into a Fourier series. The harmonic balance method gives a set of non‐linear algebraic equations in terms of the vibrating frequency and the Fourier coefficients of nodal displacements. The non‐linear algebraic equations are solved by the Newtonian algorithm iteratively. The combined algorithm is called the incremental harmonic balance method. The importance of the conditions of completeness and balanceability is presented. Since the non‐linearity is essentially softening, different orders of internal resonances between two modes can occur repeatedly. Isolated response curves are possible and are connected to the bifurcation of a particular excited mode.
Local‐soil and source‐mechanism effects in the 1986 kalamata (Greece) earthquake
Authors: Gazetas George , Dakoulas Panos , Papageorgiou Apostolos 
Published: April 2007

AbstractAn Ms ∼ 6 earthquake, originating at a normal fault directly underneath the town of Kalamata, caused substantial structural damage to reinforced‐concrete and masonry buildings, to contemporary as well as centuries‐old churches, and to a major harbour quaywall. Two accelerograms were recorded on stiff alluvial deposits. The seismologic and engineering facts of the earthquake are presented in the first half of the paper. Particular attention is paid to the non‐uniform pattern of damage distribution, at both regional and local scale. The second half of the paper investigates the possible role of the ‘local soil conditions’ and of the ‘mechanics of the source’ in the observed pattern of damage and in the amplitude and frequency composition of the two records. To this end, numerical modelling of site‐specific motions is attempted using state‐of‐practice methods, and utilizing the results of an extensive geotechnical exploration programme. It is concluded that substantial evidence does exist indicating that both soil and source effects have contributed to the non‐uniform spatial distribution of damage. The effect of through‐soil ‘filtering’ of the seismic waves appears most evident in the coastal neighbourhoods of the town, where the underlying loose saturated silty sands in the over‐50 m‐deep soil deposit may have played a beneficial role in weakening the ground‐surface shaking; the structural damage in these areas was insignificant. Qualitative arguments are also put forward for explaining some aspects of the observed pattern of damage in terms of fault orientation and ‘directivity’ effects.
Assessment of errors in the newmark method in structural dynamics
Authors: Warburton G. B. 
Published: April 2007

AbstractIn the Newmark and other approximate step‐by‐step methods, having introduced assumptions in order to transform the differential equations, which are characteristic of response problems, into simultanéous equations, successive solutions lead to a response‐time history. In this paper numerical results and formulae are given for the errors which are generated by this procedure. These errors are oscillatory in nature and, in general, the oscillations increase in magnitude as the number of time steps increases. Recommendations for upper limits on the time step, which will provide acceptable accuracy for a wide range of system and excitation parameters, are presented.
Soil‐structure interaction effects for laterally excited liquid storage tanks
Authors: Veletsos A. S. , Tang Y. 
Published: April 2007

AbstractA comprehensive study is made of the effects of soil‐structure interaction on the response of liquid containing, upright, circular cylindrical tanks subjected to a horizontal component of ground shaking. A simple, physically motivated method of analysis is employed which elucidates the effects and relative importance of the principal actions involved. Both the impulsive and convective actions of the liquid are examined. The interrelationship of the tank responses to horizontal and rocking actions of the foundation is established, and the well known mechanical model for laterally excited, rigid tanks supported on a non‐deformable medium is generalized to permit consideration of the effects of tank and ground flexibilities and base rocking. Critical responses are evaluated for harmonic and seismic excitations over wide ranges of tank proportions and soil stiffnesses, and the results are presented in a form convenient for use in practical applications. In addition to a precise method of analysis, an approximate, hand‐computation method is presented with which the effects of the primary parameters may be evaluated readily. The soil‐structure interaction effects in the latter approach are provided for by modifying the natural frequency and damping of the tank‐liquid system and evaluating its response to the prescribed free‐field ground motion considering the tank to be rigidly supported at the base. The requisite modifications may be determined from information presented herein. It is shown that soil‐structure interaction may reduce significantly the impulsive components of response but that it has a negligible effect on the convective components.
Ground motion amplification by cylindrical valleys embedded in a layered medium
Authors: Bouden M. , Khair K. R. , Datta S. K. 
Published: April 2007

AbstractThe phenomenon of localized amplification of seismic waves due to subsurface irregularities has attracted the attention of seismologists and engineers for many years. In this paper we present a hybrid numerical method to investigate the ground motion amplification due to sedimentary basins. This method combines the integral representation and the finite element to solve the scattering problem due to an arbitrary cylindrical scatterer. A study is done on two shapes of valleys to show the effect of the angle of incidence, the incident wave type and the layering on the amplification of the surface displacement components by different valleys.
Dynamic behaviour of rocking two‐block assemblies
Authors: Psycharis Ioannis N. 
Published: April 2007

AbstractThe dynamic behaviour of systems consisting of two blocks, one placed on the top of the other, and free to rock without sliding, is examined in this analysis. The equations of motion for each ‘mode’ of vibration are derived and criteria for the initiation of rocking and the transition between modes are given. During vibration, the system continuously changes from one mode to another and this makes the response non‐linear. This transition may be accompanied by impact, in which case dissipation of energy occurs, the amount of which depends on the relative velocities and the dimensions of the blocks. Also, redistribution of the kinetic energy of the system in the blocks happens. In most cases, the fractional contribution from the upper block to the system energy increases, which results in a larger and longer response of the top block, compared to the vibration of the lower one.
Hybrid experiments on non‐linear earthquake‐induced soil‐structure interaction
Authors: Toki Kenzo , Sato Tadanobu , Kiyono Junji , Garmroudi Nozar Kishi , Emi Susumu , Yoshikawa Masaaki 
Published: April 2007

AbstractNon‐linear seismic soil‐structure interaction is studied through a hybrid procedure using the pseudo‐dynamic testing (PDT) method which is modified to take into account frequency dependence and developed for foundation‐soil systems. The numerical scheme used in conventional PDT is improved by introduction of a time‐dependent pseudo‐forcing function which is derived from frequency‐dependent dynamic characteristics of the system by means of Hilbert transformation in the frequency domain. Surface, shallow and caisson foundation models that differed in size and depth of embedment were used. The mechanical characteristics of the systems were determined from static and forced vibration dynamic tests. An amplitude scaling technique was used for three recorded accelerograms.
Three‐dimensional response of a cylindrical canyon in a layered half‐space
Authors: Luco J. E. , Wong H. L. , De Barros F. C. P. 
Published: April 2007

AbstractAn indirect boundary‐method formulation to obtain the three‐dimensional response of an infinitely long canyon of uniform but arbitrary cross‐section cut in a layered viscoelastic half‐space is presented. Seismic excitation in the form of plane elastic waves acting at an arbitrary angle with respect to the axis of the canyon is considered. Numerical results for SH‐, SV‐ and P‐wave excitation of a circular canyon and of a canyon with a topography similar to that in the vicinity of Pacoima Dam are discussed in some detail.
Probabilistic representation and transmission of earthquake ground motion records
Authors: Masri S. F. , Miller R. K. , Traina M.‐I. 
Published: April 2007

AbstractA relatively simple and straightforward procedure is given for representing analytically defined or data‐based covariance kernels of arbitrary random processes in a compact form that allows its convenient use in later analytical random vibration response studies. The method is based on the spectral decomposition of the random process by the orthogonal Karhunen‐Loeve expansion and the subsequent use of least‐squares approaches to develop an approximating analytical fit for the data‐based eigenvectors of the underlying random process. The resulting compact analytical representation of the random process is then used to derive a closed‐form solution for the non‐stationary response of a damped SDOF harmonic oscillator. The utility of the method for representing the excitation and calculating the mean‐square response is illustrated by the use of an ensemble of acceleration records from the 1971 San Fernando earthquake.
A semi‐analytical boundary element method for scattering of waves in a half space
Authors: Yuan Cao Zhi , Xiong Zhu Jian , Cheung Y. K. 
Published: April 2007

AbstractA boundary element method using finite strip discretization is proposed to investigate the three‐dimensional scattering behaviour of waves in a half space. The scatterers examined are an irregular surface and a cavity in a half space. The numerical examples demonstrate the remarkably good accuracy of the results and validate the application of the present method to solve three‐dimensional scattering problems.
Earthquake physical damage and functional serviceability of lifeline network models
Authors: Kawakami Hideji 
Published: April 2007

AbstractThe connectivity of lifeline systems is studied in this paper in terms of two ratios: ‘damage ratio’, which is the degree of physical damage to the system, and is defined as the expected number of failures per unit length or per link; and ‘service ratio’, which is a measurement of system operation. First, the relationship between the two ratios in a historic event is examined. Second, a method is developed for determining this relationship in simple network systems immediately following an earthquake. Density function, expected value and covariance of service ratio are calculated as functions of the damage ratio. Even in a simple checkerboard‐type network, the density function of the service ratio has two peaks. Third, the variation in reliability of the network is examined with respect to difference in scale and configuration of the network, which may accompany growth of the community. When the damage ratio is small, the service ratio of a complex network is as large as, or larger, than that of a simple network. This pattern is, however, reversed for larger damage ratios. Finally, the relationship prior to operation restoration is examined. During the initial stages of restoration, the service ratio increases steeply, almost linearly, with decrease in the damage ratio. The increase then slows in the last stages of restoration.
A methodology for dynamic analysis of linear structure‐foundation systems with local non‐linearities
Authors: Ibrahimbegovic Adnan , Wilson Edward L. 
Published: April 2007

AbstractAn efficient computational technique is presented for the dynamic analysis of large linear structural systems with local non‐linearities. The earthquake response evaluation for many practical structures belongs to this class of problems. The technique provides a rational approach to the earthquake‐resistant design of structure‐foundation systems with predetermined non‐linearities occurring along the structure‐foundation interface. Various possibilities for base isolation systems are naturally fitted within the proposed framework. In particular, we address uplifting of the structure as a natural base isolation concept. We use the dynamic substructuring technique and an efficient numerical algorithm which accommodates non‐proportional damping as a consistent way to reduce significantly the computational effort, which is in sharp contrast to the vast majority of ad‐hoc simplified models used for the same purpose. A numerical example which demonstrates the vibration isolation effect when the uplifting of the concrete gravity dam occurs is also presented.