bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal nitric oxide synthase and calbindin delineate sex differences in the developing hypothalamus and preoptic area
Authors: Edelmann Michelle , Wolfe Cory , Scordalakes Elka M. , Rissman Emilie F. , Tobet Stuart
Published: March 2007

Throughout the hypothalamus there are several regions known to contain sex differences in specific cellular, neurochemical, or cell grouping characteristics. The current study examined the potential origin of sex differences in calbindin expression in the preoptic area and hypothalamus as related to sources of nitric oxide. Specific cell populations were defined by immunoreactive (ir) calbindin and neuronal nitric oxide synthase (nNOS) in the preoptic area/anterior hypothalamus (POA/AH), anteroventral periventricular nucleus (AVPv), and ventromedial nucleus of the hypothalamus (VMN). The POA/AH of adult mice was characterized by a striking sex difference in the distribution of cells with ir‐calbindin. Examination of the POA/AH of androgen receptor deficient Tfm mice suggests that this pattern was in part androgen receptor dependent, since Tfm males had reduced ir‐calbindin compared with wild‐type males and more similar to wild‐type females. At P0 ir‐calbindin was more prevalent than in adulthood, with males having significantly more ir‐calbindin and nNOS than have females. Cells that contained either ir‐calbindin or ir‐nNOS in the POA/AH were in adjacent cell groups, suggesting that NO derived from the enzymatic activity of nNOS may influence the development of ir‐calbindin cells. In the region of AVPv, at P0, there was a sex difference with males having more ir‐nNOS fibers than have females while ir‐calbindin was not detected. In the VMN, at P0, ir‐nNOS was greater in females than in males, with no significant difference in ir‐calbindin. We suggest that NO as an effector molecule and calbindin as a molecular biomarker illuminate key aspects of sexual differentiation in the developing mouse brain. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Evaluating the implementation of the Nitrates Directive in Denmark and England using an actor‐orientated approach
Authors: Smith Rebecca J. Nimmo , Glegg Gillian A. , Parkinson Rob , Richards Jo P.
Published: March 2007

The Nitrates Directive (91/676/EEC) was adopted to address the issue of water pollution caused by nitrate derived from agricultural practices across the European Union (EU). This study evaluates the implementation of the Nitrates Directive by considering the perspectives of respondents from significant actor groups involved in the policy implementation process in Denmark and England. Structured field interviews were conducted and discovered that Nitrate Vulnerable Zone (NVZ) designation in England was a lengthy and inefficient process compared with that in Denmark. Generally, respondents from both countries considered that whole country designation was a more effective policy instrument than designation of discrete zones. Denmark's Action Programme measures reflected the severity of its water quality problems and go beyond the demands of the Nitrates Directive. The respondents recognized that Denmark's strict measures have led to a reduction in nitrate leaching and a decline in nitrate concentrations in streams from cultivated catchments. England's current Action Programme measures do not demand any substantial changes to farming practice and so have limited potential to reduce nitrate losses. This study concludes that a number of vague and ill prepared guidelines within the Nitrates Directive undermine its ability to protect water quality adequately, and hence current implementation of the Water Framework Directive (WFD) is an opportunity to re‐shape water policy in relation to nitrate. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
Mixed‐Metal Dawson Sandwich Complexes: Synthesis, Spectroscopic Characterization and Electrochemical Behaviour of Na16[MIICo3(H2O)2(P2W15O56)2] (M = Mn, Co, Ni, Zn and Cd) (Eur. J. Inorg. Chem. 11/2007)
Authors: Ruhlmann Laurent , Costa‐Coquelard Claure , Canny Jacqueline , Thouvenot René
Published: March 2007

The cover picture shows the synthesis of the mixed‐metal Dawson sandwich complexes [MCo3(H2O)2(P2W15O56)2]16− by the addition of the transition metal cation M2+ to the “lacunary” sandwich complex [NaCo3(H2O)2(P2W15O56)2]17−. This “lacunary” species is a good precursor for the preparation mixed‐metal sanswich complexes, with promising interesting catalytic, electrocatalytic and magnetic properties. Details of the synthesis and the structural characterization in solution are discussed in the article by L. Ruhlmann and R. Thouvenot on p. 1493 ff.
Amperometric Tyrosinase Biosensor Based on Carbon Nanotube–Titania–Nafion Composite Film
Authors: Lee You‐Jin , Lyu Young‐Ku , Choi Han Nim , Lee Won‐Yong
Published: March 2007

A highly sensitive and stable amperometric tyrosinase biosensor has been developed based on multiwalled carbon nanotube (MWCNT) dispersed in mesoporous composite films of sol–gel‐derived titania and perfluorosulfonated ionomer (Nafion). Tyrosinase was immobilized within a thin film of MWCNT–titania–Nafion composite film coated on a glassy carbon electrode. Phenolic compounds were determined by the direct reduction of biocatalytically‐liberated quinone species at −100 mV versus Ag/AgCl (3 M NaCl) without a mediator. The present tyrosinase biosensor showed good analytical performances in terms of response time, sensitivity, and stability compared to those obtained with other biosensors based on different sol–gel matrices. Due to the large pore size of the MWCNT–titania–Nafion composite, the present biosensor showed remarkably fast response time with less than 3 s. The present biosensor responds linearly to phenol from 1.0×10−7 M to 5.0×10−5 M with an excellent sensitivity of 417 mA/M and a detection limit of 9.5×10−8 M (S/N=3). The enzyme electrode retained 89% of its initial activity after 2 weeks of storage in 50 mM phosphate buffer at pH 7.0.
Characterization of Mercury – Humic Acids Interaction by Potentiometric Titration with a Modified Carbon Paste Mercury Sensor
Authors: Gismera M. Jesús , Procopio Jesús R. , Sevilla M. Teresa
Published: March 2007

Stability constant for mercury binding by commercial and natural humic acids (HA) were determined using a new potentiometric mercury(II) sensor based on dithiosalicylic acid modified carbon paste electrode. The sensor present a high selective and sensitive response to mercury(II) ions, and a low detection limit of 1.8×10−8 M. The potentiometric titrations curves of humic acids against mercury(II) ions were modeled. For 1.00×10−7 to 3.00×10−4 M mercury(II) ion concentration levels the results are consistent with the presence of two different binding sites in the humic acid macromolecule. The strongest binding sites (log K1 ranging from 10.1 to 6.8) are probably due to interaction with carboxylic acid and amine groups in the molecule, whereas weakest binding sites (log K2 ranging from 8.8 to 4.5) can be associated to phenolic groups.
Ultrathin Carbon Nanoparticle Composite Film Electrodes: Distinguishing Dopamine and Ascorbate
Authors: Amiri Mandana , Shahrokhian Saeed , Marken Frank
Published: March 2007

Ultrathin carbon nanoparticle–poly(diallyldimethylammonium chloride) films (CNP‐PDDAC films) are formed on tin‐doped indium oxide (ITO) electrodes in a layer‐by‐layer electrostatic deposition process employing 9–18 nm diameter carbon particles. Transparent and strongly adhering films of high electrical conductivity are formed and characterized in terms of their electrochemical reactivity. When immersed in aqueous 0.1 M phosphate buffer pH 7, each layer of CNP‐PDDAC (of ca. 5–6 nm average thickness) is adding an interfacial capacitance of ca. 10 μF cm−2. Absorption into the CNP–PDDAC nanocomposite film is dominated by the sites in the PDDAC cationomer and therefore anionic molecules such as indigo carmine are strongly bound and retained within the film (cationic binding sites per layer ca. 150 pmol cm−2). In contrast, cationic redox systems such as ferrocenylmethyltrimethyl‐ammonium+ fail to bind. For solution phase redox systems such as hydroquinone, the rate of electron transfer is dramatically affected by the CNP‐PDDAC film and switched from completely irreversible to highly reversible even with a single layer of carbon nanoparticles. For the mixed redox system ascorbate–dopamine in 0.1 M phosphate buffer pH 7 cyclic voltammograms suggest a rapid and selective temporary poisoning process which causes the ascorbate oxidation to be suppressed in the second potential cycle. This effect is exploited for the detection of micromolar concentrations of dopamine in the presence of millimolar ascorbate.
EQCM Study of Ru and RuO2 Surface Electrochemistry
Authors: Juodkazytė J. , Vilkauskaitė R. , Stalnionis G. , Šebeka B. , Juodkazis K.
Published: March 2007

The present study represents comparative analysis of voltammetric and microgravimetric behavior of active ruthenium (Ru), electrochemically passivated ruthenium (Ru/RuO2) and thermally formed RuO2 electrodes in the solutions of 0.5 M H2SO4 and 0.1 M KOH. It has been found that cycling the potential of active Ru electrode within E ranges 0 V–0.8 V and 0 V–1.2 V in 0.5 M H2SO4 and 0.1 M KOH solutions, respectively, leads to continuous electrode mass increase, while mass changes observed in alkaline medium are considerably smaller than those in acidic one. Microgravimetric response of active Ru electrode in 0.5 M H2SO4 within 0.2 V–0.8 V has revealed reversible character of anodic and cathodic processes. The experimentally found anodic mass gain and cathodic mass loss within 0.2–0.8 V make 2.2–2.7 g F−1, instead of 17 g F−1, which is the theoretically predicted value for Ru(OH)3 formation according to equation: Ru+3H2O⇌Ru(OH)3+3H++3e−. In the case of Ru/RuO2 electrode relatively small changes in mass have been found to accompany the anodic and cathodic processes within E range between 0.4 V and 1.2 V in the solution of 0.5 M H2SO4. Meanwhile cycling the potential of thermally formed RuO2 electrode under the same conditions has lead to continuous decrease in electrode mass, which has been attributed to irreversible dehydration of RuO2 layer. On the basis of microgravimetric and voltammetric study as well as the coulometric analysis of the results conclusions are presented regarding the nature of surface processes taking place on Ru and RuO2 electrodes.
Conservatism in summation rules for closely spaced modes
Authors: Kelly James M. , Sackman Jerome L.
Published: March 2007

It is shown that the method recommended by the Nuclear Regulatory Commission to be used to combine spectral response in the case of closely spaced modes is unnecessarily conservative for certain systems. Closely spaced modes arise in structures from symmetry and where there is a light appendage with a frequency close to one of the natural frequencies of the structure. In the former case, the closely spaced modes do not involve significant interaction between components of the system and the Nuclear Regulatory Commission Guide is reasonable. The latter case, that is when there are closely spaced modes where interaction of components occurs as in the examples of light appendages and torsionally unbalanced buildings, must be treated by consideration of the interacting components. The approach proposed here is that the modes that are not closely spaced be treated by modal analysis and the closely spaced modes, in the case of two closely spaced modes, be treated as a coupled two‐degree‐of‐freedom system. If this is done, the beat phenomenon, the most important characteristic of the interaction, is evident, as is the associated result that the peak response of the coupled system is developed much later than the peak responses obtained in the individual modes. It is shown that the square root of the sum of the squares procedure underestimates, as expected, the response for undamped and very lightly damped systems, but for damped systems the square root of the sum of the squares method can be extremely conservative. It follows that the other methods specified by the Nuclear Regulatory Commission for closely spaced modes must be even more conservative.
Dynamic response of an elastic‐viscoplastic system in modal co‐ordinates
Authors: Lukkunaprasit Panitan , Widartawan Stephen , Karasudhi Pisidhi
Published: March 2007

A dynamic analysis of elastic–viscoplastic systems, incorporating the modal co‐ordinate transformation technique, is presented. The formulation results in uncoupled incremental equations of motion with respect to the modal co‐ordinates. The elastic–viscoplastic model adopted allows the analysis not to involve yielding regions and loading/unloading processes. An implicit Runge–Kutta scheme together with the Newton–Raphson method are used to solve the non‐linear constitutive equations. Stability and accuracy of the numerical solution are improved by utilizing a local time step sub‐incrementing procedure.

Applications of the analyses to multi‐storey shear buildings show that good results can be obtained for the maximum displacement response by including only a few lower modes in the computation, but the prediction of the ductility factor response tends to underestimate the peak values when too few modes are used. In addition, stable and valid results can be obtained even with a sizable time step increment.
Identification of a one‐dimensional model for a soil‐layer–bedrock system during an earthquake
Authors: Tomizawa Minoru
Published: March 2007

The propriety of adopting a multi‐degree‐of‐freedom lumped mass–spring–dampers system driven by white noise support excitation as a one‐dimensional model for a soil‐layer–bedrock system during an earthquake is investigated by means of statistical system identification of the model with noisy measurement of the earthquake ground velocity. The present discussion also suggests that this model may not be applicable to all observed earthquake records, since the model itself depends on the statistical nature of the earthquake motion. For appropriate earthquake records, the system identification procedure may be accomplished; then dynamical properties of the soil‐layer and the power spectral density for white noise excitation acting upon the bedrock can be estimated as shown in a numerical example.
Resonance capacity method for earthquake response analysis of hysteretic structures
Authors: Yamada Minoru , Kawamura Hiroshi
Published: March 2007

The Resonance Capacity Method is proposed for the earthquake response analysis of hysteretic structures. Resonance Capacity is a physical quantity of structures which is related to the hysteretic energy absorbed by structures in one cycle and is equated to the acceleration, velocity and displacement amplitudes α0, d0 and d0 of earthquake ground motions at resonance.1 According to the idealized trapezoidal approximation of earthquake ground motions in the logarithmic period–velocity plane as proposed by Veletsos and Newmark,8 the Resonance Capacity property applies in each period range, short, medium and long, where α0, v0 and d0 respectively are approximately constant. In the medium range of periods, the energy dissipated in hysteretic loops and the deformation amplitudes of a single‐degree system with elasto–plastic force–deformation relationships are calculated for the case of El Centro 1940, 18 May earthquake, by this Resonance Capacity Method. The result is compared with results from conventional numerical response analyses obtained by Berg and Thomaides,14 Kato and Akiyama12 and Veletsos and Newmark,8 and the general agreement is seen to be good. Therefore, it may be possible to apply this Resonance Capacity Method over the entire range of periods. By means of this method the earthquake response analysis of hysteretic systems can be performed easily, and the hysteretic energy and fatigue characteristics of structures may be taken into account directly, up to the point of fracture.
Seismicity and seismic intensities in Jamaica, West Indies: A problem in risk assessment
Authors: Shepherd John B. , Aspinall W. P.
Published: March 2007

A review of the history of earthquake observations in Jamaica is presented; there have been several high‐intensity earthquakes in the last 300 years. The observed seismicity of the Jamaica region is discussed in the context of what is known of regional tectonics, and possible source regions of earthquakes are identified but a comparison between instrumentally determined seismicity and macroseismicity shows that the instrumental data are of insufficient quantity or quality to permit direct assessment of earthquake risk by conventional techniques. An alternative approach has been adopted; consideration of the macroseismic record suggests that the peak acceleration in rock with 90 per cent probability of not being exceeded in any 50‐year period is of order 0.3 g but that there are very significant local variations caused by near‐surface geology. Especially this applies to the capital, Kingston, and envelope response spectra are derived for shallow, intermediate and deep thickness of sediments under the city to demonstate the possibility that localized amplification may occur.

A current apparent decline in the seismicity of the Jamaica region is noted but it is shown that the decline in the number of earthquakes of engineering interest is not yet statistically significant.
A methodology for locating strong motion arrays
Authors: Udwadia F. E. , Miura H.
Published: March 2007

This paper investigates a methodology for locating strong motion accelerographs in a seismically active region. Starting with the probability density of earthquakes in a given region, the paper attempts, within the framework of optimization theory, to formulate the following two questions: (1) given N accelerographs, where should they be located in a seismically active zone, and (2) having fixed these N accelerographs, where should the next M be located?

Three different cost functions are presented. Some closed form solutions are illustrated for problems when N and M are small. For larger arrays, numerical optimization is resorted to.

To demonstrate the methodology, a region with J faults, with given spatial locations is selected. An efficient algorithm for optimization is utilized and the technique illustrated. Good agreement with closed form solutions obtained in some simple cases is indicated. Specific application of the method to the placing of twenty strong motion instruments in a seismically active area has been carried out, and the patterns of sensor location, for each of the cost functions, illustrated.
Effects of seismic wave propagation upon buried pipelines
Authors: O'Rourke Michael J. , Castro Gerardo , Centola Naneen
Published: March 2007

The behaviour of long straight buried pipelines subjected to seismic wave propagation is investigated. Well‐known relationships for determining upper bounds for the axial strain and curvature in the pipeline as well as relationships for relative displacement and rotation at the pipeline joints are discussed. The assumption that the seismic excitation can be modelled as a travelling wave having a shape which remains unchanged as it traverses the pipeline is examined in detail. It is shown that this assumption is unconservative when the effective propagation velocity of the seismic waves with respect to the pipeline is such that the actual time lag (separation distance between points divided by effective propagation velocity) is less than a ‘cross‐over’ time lag. Cross‐over time lags for 22 pairs of ground displacements recorded during the 1971 San Fernando Earthquake are presented in this paper. Finally, methods for estimating the propagation speed of the seismic waves along or with respect to the pipeline are discussed.
Response of fixed offshore structures in random sea
Authors: Angelides Demosthenes C. , Connor Jerome J.
Published: March 2007

An integrated model is developed for the short‐term and long‐term dynamic response of an offshore structure subjected to random wave excitation. A discrete linear, elastic model of the upper structure is coupled with an iterative linear quasi‐three‐dimensional finite element model for the pile‐soil medium, and the system is subjected to stochastic storms described by mean rate of arrival, joint probability distribution of storm duration and average intensity, and a random process that describes the variations of a statistical wave height measure during each storm. Sarpkaya's 1977 experimental information is used to specify values for CM and CD, in Morison's equation, consistent with the flow and response characteristics. Soil (clay) degradation, due to cyclic excitation, is followed during the passage of a storm. The indicator of soil degradation is taken to be the value of the horizontal foundation stiffness and the stiffness degradation is modelled by a homogeneous Markov process.
Efficient transient dynamic plate bending analysis with mindlin elements
Authors: Pica A. , Hinton E.
Published: March 2007

The efficiency of a transient dynamic plate bending solution procedure based on the use of Mindlin plate elements with a central difference time stepping scheme is improved by suitably modifying the rotatory inertia terms in the diagonalized mass matrix.
A novel spherical polar finite element for the solution of the steady‐state scalar wave equation in three‐dimensions
Authors: Nath B.
Published: March 2007

A novel method has been proposed for the finite element solution of the steady‐state scalar wave equation in three‐dimensions. In this the governing equation and the prescribed boundary conditions in the physical space are transformed into a spherical polar space in which the radial direction is logarithmically condensed; the physical problem domain is also mapped into the new space. The transformed equation is then solved in the mapped domain using conventional finite elements. Because physical dimensions of the problem are logarithmically condensed in the proposed spherical polar space, the method is particularly suitable for solving truly three‐dimensional problems in which the aspect ratio(s) is large or very large.

A number of illustrative examples considered show that the proposed method is capable of a high degree of accuracy, achieved efficiently and economically. A hybrid scheme has also been proposed for dealing with awkward‐shaped domains.
Dynamic characteristics of lateral load‐deflection relationships of flexible piles
Authors: Kagawa Takaaki , Kraft Leland M.
Published: March 2007

Most offshore platforms are supported on long and large‐diameter piles with variable wall‐thickness along the length, and soil properties varying with depth. The design and analyses of these piles are made by modelling the soil‐pile system with a beam‐on‐Winkler foundation. Therefore, evaluation of appropriate soil‐pile springs for use in such analyses is a matter of concern. Fundamental characteristics of dynamic lateral load‐deflection relationships for piles were studied analytically considering the soil‐pile‐structure interaction under seismic loading conditions. The soil layer was assumed homogeneous, linearly elastic with hysteretic type material damping, and overlying a rigid base. A superstructure with multi‐degrees of freedom was supported by a single vertical pile hinged at the rigid base.

Parametric studies were carried out to identify the influence of the system parameters on the behaviour of the dynamic lateral load‐deflection relationships of piles. The lateral load‐deflection relationships vary considerably with depth and are influenced not only by the dynamic properties of soil but also by the structural properties of a pile and loading conditions. These lateral load‐deflection relationships can be used to define the soil‐pile springs for the seismic response analysis of a soil‐pile‐structure system, and the results can be extended to problems with soil profiles with layering and non‐linearity.
A linearization scheme for hysteretic systems subjected to random excitation
Authors: Grossmayer Rudolf L. , Iwan Wilfred D.
Published: March 2007

The problem of predicting the response of hysteretic yielding systems under random excitation is considered. The paper presents a linearization scheme which is motivated by extensive simulation studies of the bilinear hysteretic system. The response process is decomposed into a low frequency drift component and a component with a frequency near the linearized natural frequency of the system. Effective stiffness and damping parameters are presented. The accuracy of the various steps of the scheme is examined. The approach gives results which are in close agreement with simulation estimates even for large‐system non‐linearity.
On the moments of time to first passage of the linear oscillator
Authors: Bergman L. A. , Heinrich J. C.
Published: March 2007

The moments of time to first passage of the response process of the linear oscillator excited by a stationary wide‐band process are obtained numerically for the symmetric two‐sided barrier problem. A recursive set of partial differential equations governing the moments is solved using a Petrov‐Galerkin finite element method. Stable, accurate solutions for the first few moments are calculated over a wide range of oscillator damping.
An approximate method for soil‐structure interaction for sh‐waves—the born approximation
Authors: Chu L. L. , Askar A. , Cakmak A. S.
Published: March 2007

An approximate method is proposed for the scattering of SH‐waves by foundations of irregular shape and the resulting soil‐structure interaction problems. The scattering of elastic waves by the rigid foundation embedded in half‐space is solved approximately by using integral representation of the wave equation. The procedure is the Born approximation which has been widely used in quantum mechanics for collision and scattering theory though not well‐known in elastodynamics. This paper extends the previous work of the authors on the scattering of waves to account for soil‐structure interaction. The motion of the foundation is evaluated by the balance of momentum under stresses due to the incident waves as well as the waves generated by its own motion and the forces coming from the superstructure. The model investigated consists of an infinitely long elastic shear wall of height H and thickness h erected on a rigid infinitely long foundation. Results are presented for the cases with circular, elliptical and rectangular foundations. For a circular foundation, excellent agreement is found with the exact solutions for the foundation displacement and the relative displacement between the top and bottom of the structure for the entire range of wave numbers. For an elliptical foundation, accuracy decreases with increasing wave numbers. Foundation displacements are compared for foundation shapes that are shallow elliptical, deep elliptical, rectangular and circular. It is observed that foundation displacements are dependent on the angle of incidence except for a semi‐circle. The results on the details of the scattered field are, however, not as accurate.
Torsional instability in structures
Authors: Antonelli Richard G. , Meyer Keith J. , Oppenheim Irving J.
Published: March 2007

Torsional instability under harmonic excitation was detected in structures with cubic softening member stiffness. A variational procedure was introduced to perform the analysis for the general problem formulation. Single‐storey structures with zero eccentricity were studied first; previous findings were checked and corrected, and the behaviour was examined in greater detail. Two‐storey structures with large eccentricity were also examined, and further regions of torsional instability were detected. Time history analysis was then employed to quantify the behaviour of various typical structures. An unbounded growth in rotation or column displacement was not observed. Rather, the instability appeared to be related to the jump in response which exists in single degree‐of‐freedom softening oscillators subjected to harmonic excitation. The practical significance of torsional instability is therefore rather weak, although prudent practice would recommend its avoidance.
Beam models for predicting dynamic elastic response
Authors: Neubert V. H. , Rangaiah V. P.
Published: March 2007

Further investigation of the three‐parameter lumped mass model for the prediction of natural frequencies and transient response of Bernoulli‐Euler clamped‐clamped beams has resulted in a revised model, which is slightly superior to the original model, as it is applicable over a wider frequency range.
Non‐parametric identification of a class of non‐linear close‐coupled dynamic systems
Authors: Udwadia F. E. , Kuo Chin‐Po
Published: March 2007

A non‐parametric identification technique for the identification of arbitrary memoryless non‐linearities has been presented for a class of close‐coupled dynamic systems which are commonly met with in mechanical and structural engineering. The method is essentially a regression technique and expresses the non‐linearities as series expansions in terms of orthogonal functions. Whereas no limitation on the type of test signals is imposed, the method requires the monitoring of the response of each of the masses in the system. The computational efficiency of the method, its easy implementation on analogue and digital machines and its relative insensitivity to measurement noise make it an attractive approach to the non‐parametric identification problem.
Layered soil‐pile‐structure dynamic interaction
Authors: Takemiya Hirokazu , Yamada Yoshikazu
Published: March 2007

This paper is concerned with the dynamic interaction between soil, pile and structure when subjected to harmonic excitation at the base rock level. The structure to be analysed is an isolated tall bridge pier with deep group pile foundation. The dynamic substructure approach is taken, dealing first with the pile‐footing substructure and the pier superstructure independently; and then integrating these at the interface. Since the soil profile is multi‐layered, the transfer matrix scheme is applied to extend the relevant continuum solution proposed by earlier researchers for pile analysis in a homogeneous viscoelastic medium.

Using a numerical example, the importance of the soil layer vibration modes which exert forces on the pile varying along the pile length is pointed out together with the soil‐structure inertial interaction in the structural response. The latter concerns the dynamic characteristic of the complete system whereas the former relates the driving force to it. Also examined is the applicability of the approximate soil reaction based on the plane strain assumption, which simplifies the formulation and requires much less computing time in the response analysis.
Impact study by various bridge models
Authors: Wiriyachai A. , Chu Kaung‐Han , Garg V. K.
Published: March 2007

In previous studies of train‐bridge interactions, impact percentages for member forces have been obtained by use of a pin‐connected truss model and for both member forces and moments by use of a rigid joint truss model. The purpose of this study is three‐fold: (a) to investigate if improved results can be obtained by use of semirigid connections at the ends of the floor beams and stringers; (b) to develop partial bridge models, for studying impacts and the range of forces and moments in members subjected to fatigue; (c) to employ a partial bridge model to study the influences of various factors on the impact factors and stress ranges of the various members and connections of the truss bridge. Descriptions of the bridge and vehicle models and the associated equations of motion are briefly stated, and results from the various bridge models are compared.
Energy dissipation and seismic liquefaction in sands
Authors: Ishac Magdi F. , Heidebrecht Arthur C.
Published: March 2007

A statistical representation of seismic liquefaction is advanced based on the postulate that pore water pressure increases are proportional to the dissipated seismic energy density. The representation, based on approximately fifty case histories, relates the pore pressure increase to earthquake magnitude, distance to centre of energy release, initial effective overburden stressand standard penetration value. The model may be used for analysis ofseismic liquefaction risk. An example analysis for the ‘South of Market Zone’ in San Francisco is carried out in relation to earthquakes on the San Andreas fault.
Buckling of cylindrical liquid‐storage tanks under earthquake loading
Authors: Niwa Akira , Clough Ray W.
Published: March 2007

The earthquake response behaviour of a cylindrical wine storage tank similar to many that were damaged in Livermore, California during the January 1980 earthquake was studied on the University of California shaking table. Tests of the 9.5 ft diameter by 20 ft high tank, with simulated earthquake accelerations up to 0.95 g, induced buckling patterns similar to those observed after the actual earthquake. Observed peak axial compression stresses in the test tank wall were substantially higher than those assumed in typical design standards, demonstrating the need for further study of the buckling problem in tanks free to uplift during earthquake excitation.
Variability of tall building response to earthquakes with changing epicentre direction
Authors: Yang J. N. , Sae‐Ung S. , Lin Y. K.
Published: March 2007

Using a 40‐storey building as an example, the structural response under the excitation of horizontal earthquake ground motion is shown to vary greatly with the direction from the building site to the epicentre. Two mathematical models are used to represent the ground motion: the stationary random process model and the evolutionary‐type non‐stationary random process model. The former model is suitable if the duration of the most intense portion of an earthquake is much longer than the fundamental natural period of the structure. The maximum standard deviations of selected structural response quantities are computed and plotted for all possible epicentre directions, and the information is believed to be useful for design purposes.
Horizontally travelling waves in a group of piles taking pile‐soil‐pile interaction into account
Authors: Wolf John P. , von Arx Guido A.
Published: March 2007

A reactor building founded on a large number of piles situated in a layered site is analysed for an historic earthquake assumed to be propagating horizontally. Pile‐soil‐pile interaction is properly accounted for, incorporating the frequency‐dependent stiffness and radiation damping. Compared to vertical incidence, the pile forces are increased and the piles close to the boundary are loaded more heavily than those in the centre region of the basemat.
Considerations on the residual contribution in modal analysis
Authors: Salmonte Antonio J.
Published: March 2007

Mode superposition has become a standard tool in the treatment of seismic analysis. Its advantages are appealing to the analyst. After years of widespread use of the method, it could be said that it is well understood, both in theory and application. However, its routine application can lead to errors caused by the analyst neglecting truly representative modes in the system response.

In this paper, a very simple technique is suggested for representing, under certain conditions, the effect of the higher modes: the residual mode method. The effectiveness of the method in the context of response spectrum analysis is discussed, and such analysis is illustrated by a numerical example.
Local member response in offshore structures under earthquake excitations
Authors: Anagnostopoulos Stavros A. , Culbertson Arthur R.
Published: March 2007

It is pointed out that local vibrations of certain members in earthquake excited offshore structures can induce substantial stresses that may often dominate the design of these members. Such vibrations are not accounted for in dynamic analyses of structural models with masses lumped at the joints. A practical, easy to implement solution to this problem is recommended and results from an actual structure, subjected to a three‐component real earthquake, are presented demonstrating the importance of local inertia effects.
Diffraction of plane sh waves in a half‐space
Authors: Shah A. H. , Wong K. C. , Datta S. K.
Published: March 2007

Scattering of antiplane shear waves (SH) in two dimensions by surface and near‐surface defects in a homogeneous, isotropic elastic semi‐infinite medium has been studied. Attention has been focused here in the range of medium to long wavelengths. A combined finite element and analytical technique has been used to study the problems of scattering by semi‐circular and triangular canyons. The results for the former case are compared with the known exact solution and those for the latter case are compared with some available approximate solutions. Finally a problem of multiple scattering by a triangular canyon and a nearby circular tunnel is studied. Numerical results are presented showing the effects of multiple scattering and different angles of incidence. These results are of interest in earthquake engineering.
Earthquake strong motions recorded by a large near‐source array of digital seismographs
Authors: Bolt B. A. , Tsai Y. B. , Yeh K. , Hsu M. K.
Published: March 2007

Specially designed arrays of strong‐motion seismographs near to the earthquake source are required for seismological and engineering studies of the generation and near‐field properties of seismic waves. The first such large digital array, called SMART 1 (with radius 2 km and 37 accelerometers), to record substantial ground motion (up to 0·24g horizontal acceleration) became operational in late 1980 in a highly seismic region of Taiwan. During the first 6 months of operation, SMART 1 recorded nine earthquakes with magnitudes ranging from ML 3·8 to 6·9. Three were located directly below the array at focal depths of 59 to 76 km. The remaining six had shallow depths and epicentral distances from 7 to 193 km. Digital records from 27 three‐component accelerographs were obtained from a magnitude 6·9 (ML) local earthquake on 29 January 1981. Representative measurements are described of seismic wave coherency and power spectrum as a function of wave number, frequency, azimuth of propagation and wave type. Acceleration waveforms varied significantly across the array for each event. On average, peak acceleration of horizontal components was about three times that of the vertical component. Relative spectral changes from earthquake to earthquake were large.
Lead‐rubber hysteretic bearings suitable for protecting structures during earthquakes
Authors: Robinson W. H.
Published: March 2007

Lead‐rubber hysteretic bearings provide in a single unit the combined features of vertical load support, horizontal flexibility and energy absorbing capacity required for the base isolation of structures from earthquake attack. The lead‐rubber hysteretic bearing is a laminated elastomeric bearing of the type used in bridge structures, with a lead plug down its centre.

Since the invention of the lead‐rubber bearing, a total of eleven bearings up to a diameter of 650mm, with lead plugs ranging from 50 to 170mm in diameter, have been tested under various conditions, including vertical loads to 3·15 MN, strokes to ρ 110 mm, rates from 1 mm/h to 100 mm/s, and temperatures of −35°C to + 45°C. In all of these tests, the lead‐rubber bearings behaved satisfactorily and the hysteresis loops could be described reasonably well by assuming that the lead behaved as an elastic‐plastic solid with a yield stress in shear of 10·55 MPa. The bearings showed little rate dependence at ∼100 mm/s, though at creep rates of ∼1 mm/h the force due to the lead dropped to 30 per cent of that at typical earthquake frequencies. The effect of many small displacements has been tested with 11000 cycles at ±3 mm. A total of 92 lead‐rubber bearings have been used in New Zealand to base isolate one building and three bridges. They have yet to be used overseas.

This paper describes the tests on the lead‐rubber bearings, the results and a design procedure for selecting the size of the lead plug.
Dynamic characteristics of coupled wall‐frame systems
Authors: Basu Amiya K. , Dar Gulam Q.
Published: March 2007

The paper presents the first three natural frequencies and the corresponding mode shapes for fixed‐base multistorey buildings which can be idealized as an equivalent planar coupled shear wall connected in series to an equivalent frame. The coupled wall is modelled as a continuum of uniform properties and the frame as a uniform shear beam, the connection between the two elements being taken as continuous. Solutions are obtained by treating the structure as a lumped parameter system with twenty equidistant discrete masses having only translational inertia. The relevant flexibility matrix is, however, generated from the exact solution of the governing differential equation for the continuum subjected to point loading. The results are presented for various combinations of the three non‐dimensional parameters which are sufficient to describe all the geometric and material properties of the system. The mode shapes are presented in terms of the first three normal modes of a uniform slender cantilever. The non‐dimensional base shears required for the response spectrum analysis of buildings of the type under consideration are also given for the three modes and for the various combinations of the three non‐dimensional parameters mentioned above. The use of the results is illustrated by an example.
Motions of rigid bodies and criteria for overturning by earthquake excitations
Authors: Ishiyama Yuji
Published: March 2007

This investigation deals with motions of rigid bodies on a rigid floor subjected to earthquake excitations, and criteria for overturning of the bodies.

In order to study any motions of a body in a plane, the motions are classified into six types, i.e. (1) rest, (2) slide, (3) rotation, (4) slide rotation, (5) translation jump and (6) rotation jump. Then, the following are studied: the equations of motion, transitions of motion, and motions after impact between the body and the floor. One of the features of this investigation is the introduction of the tangent restitution coefficient which enables us to estimate the magnitude of the tangent impulse at the instant of impact.

A computer program was developed to simulate the motions of bodies subjected to horizontal and vertical ground motions, numerically solving the non‐linear equations of motion.

Several types of simulation were carried out and the following conclusions were found. The coefficient of friction must be greater than the breadth—height‐ratio in order for the body to rock. The motions after impact from translation jump are greatly influenced by the normal and tangent restitution coefficients. As criteria for overturning of bodies, at least two factors must be taken into account: the horizontal acceleration and the velocity of the floor. Then it is possible to estimate the motions of the floor from the overturning of bodies in a more reliable manner than before.
Vibration of beams on partial elastic foundations
Authors: Doyle Paul F. , Pavlovic Milija N.
Published: March 2007

The natural response of a beam or pile having only a portion of its span supported by an elastic foundation is investigated for the two cases when both ends are either simply supported or free. The derivation of the shape functions and the computed natural frequencies are compared with the extreme cases where the element is either completely supported by, or fully detached from, the elastic foundation.
Fatigue life of critical members in a railway truss bridge
Authors: Garg Vijay K. , Chu Kuang‐Han , Wiriyachai A.
Published: March 2007

The fatigue life of critical members, such as hangers, floor‐beams and stringers in a single track, open deck railroad truss bridge, was investigated for various unit freight trains, operating at different speeds. A partial bridge model was used, along with a three‐car train, to determine the stress cycles. For determining the fatigue lives of critical members, four fully‐loaded trains per day were assumed to pass over the bridge. Each train was assumed to consist of one hundred 70‐ton cars or seventy 100‐ton cars. The 100‐ton freight cars cause large stress ranges, and consequently shorter fatigue lives than the 70‐ton freight cars. For the hundred‐car train, with 70‐ton and 100‐ton cars mixed in various proportions, the fatigue lives became shorter as the percentage of 100‐ton cars in the consist was increased. The impact percentages were also studied.
An FFT algorithm for structural dynamics
Authors: Hall John F.
Published: March 2007

A Fast Fourier Transform algorithm (FFT) is described which is especially suited for structural dynamics. The routine incorporates several features selected from many variations of the original Cooley and Tukey1 algorithm with the goal of making the most efficient use of computer time and storage while maintaining simplicity. Some introductory material to Fourier transform techniques and a description of the original algorithm are also included. In addition, the source listing of the subroutine FFT is reproduced.
Free‐field response from inclined SH‐waves and love‐waves
Authors: Wolf John P. , Obernhuber Pius
Published: March 2007

To identify the key features of the free‐field response for antiplane motion, a vast parametric study is performed, varying the location of the control point, the nature of the wave pattern and the site properties. Harmonic and transient seismic excitations for a site consisting of a layer on bedrock and an actual soft site and a rock site are investigated.

When the control point is selected at the outcrop of the bedrock, the amplification of the motion to the free surface of the site depends on the angle of incidence of the incoming wave in the bedrock. Vertically incident, inclined SH‐waves and Love‐waves result in a very similar variation of the motion with depth. In contrast to Love‐waves the attenuation of the motion in the horizontal direction for inclined body waves depends on the damping of only the bedrock. Love‐waves thus attenuate more strongly than body waves, especially for soft sites and in the higher‐frequency range. Generally, higher Love‐modes attenuate less than the first. To determine the seismic input motion for a structure at a soft site, it seems sufficient to examine only extremely shallow body waves. For a rock site, however, Love‐waves should be investigated.
Vertical seismic behaviour of suspension bridges
Authors: Abdel‐Ghaffar A. M. , Rubin L. I.
Published: March 2007

The vertical response of suspension bridges to multi‐support seismic excitations is investigated. A frequency‐domain random‐vibration approach is utilized to take into account not only the differences in ground motion inputs, but also the correlation among the various input motions. The earthquake response of the Golden Gate Suspension Bridge, California, is analysed. The ground motion inputs were taken from an array of time histories recovered from the Imperial Valley, California, earthquake (ML = 6.6) of 15 October 1979. Mean square displacement, stress and cable tension responses are obtained. An estimation of the expected peak response is made by comparing existing methods to the results of a time‐domain analysis; it was found that a peak factor of 3.5 times the r.m.s. response is a good estimate of the expected peak response for this multiple‐input seismic problem.