Attenuation Equation Research Articles

Improved trace gas flux estimation through IRGA sampling optimization

We examine the theoretical and practical aspects of improving the sampling methods of spectroscopic trace gas sensors of Eddy covariance flux measurement systems. Theory is developed based on non-ideal ventilation devices and existing equations for tube flow and attenuation of non-reactive trace gases and temperature. Model results indicate an optimum design exists which can be expressed in relation to intake tube diameter and which depends upon the ventilation device employed. Field experiment results (employing modified open path IRGAs) show that the use of short intake tubes can reduce flux losses by trace gas signal attenuation while minimizing the adjustments required for density fluctuations, with additional benefits of increased data capture under adverse environmental conditions.

Analytical decoupling of poroelasticity equations for acoustic-wave propagation and attenuation in a porous medium containing two immiscible fluids

Poroelasticity theory has become an effective and accurate approach to analyzing the intricate mechanical behavior of a porous medium containing two immiscible fluids, a system encountered in many subsurface engineering applications. However, the resulting partial differential equations in the theory intrinsically take on a coupled form in the terms pertinent to inertial drag, viscous damping, and applied stress, making it difficult to obtain closed-form, steady-state analytical solutions to boundary-value problems except in special cases. In the present paper, we demonstrate that, for dilatational wave excitations, these partial differential equations can be decoupled analytically into three Helmholtz equations featuring complex-valued, frequency-dependent normal coordinates that correspond physically to three independent modes of dilatational wave motion. The normal coordinates in turn can be expressed in the frequency domain as three different linear combinations of the solid dilatation and the linearized increment of fluid content for each pore fluid, or equivalently, as three different linear combinations of total dilatational stress and two pore fluid pressures. These representations are applicable to strain-controlled and stress-prescribed boundary conditions, respectively. Numerical calculations confirm that the phase speed and attenuation coefficient of the three dilatational waves represented by the Helmholtz equations are exactly identical to those obtained previously by numerical solution of the dispersion relations for dilatational wave excitation of a porous medium containing two immiscible fluids. Thus, dilatational wave motions in unsaturated porous media subject to suitable boundary conditions can now be accurately modeled analytically.

Retrieval of Reflectivity in a Networked Radar Environment

Abstract A system for reflectivity and attenuation retrieval for rain medium in a networked radar environment is described. Electromagnetic waves backscattered from a common volume in networked radar systems are attenuated differently along the different paths. A solution for the specific attenuation distribution is proposed by solving the integral equation for reflectivity and attenuation. The set of governing integral equations describing the backscatter and propagation of common resolution volume are solved simultaneously with constraints on total path attenuation. The proposed algorithm is evaluated based on simulated X-band radar observations synthesized from S-band measurements collected by the Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL) radar. Retrieved reflectivity and specific attenuation using the proposed method show good agreement with simulated reflectivity and specific attenuation. Preliminary demonstration of the network-based retrieval using data from the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) IP-1 radar network are also presented.

Damage assessment of basaltic rock mass due to repeated blasting in a railway tunnelling project – A case study

The demand for tunnelling and underground space creation is rapidly growing due to the requirement of civil infrastructure projects and urbanisation. Blasting remains the most inexpensive method of underground excavations in hard rock. Unfortunately, there are no specific safety guidelines available for the blasted tunnels with regards to the threshold limits of vibrations caused by repeated blasting activity in the close proximity. This paper presents the results of a comprehensive study conducted to find out the effect of repeated blast loading on the damage experienced by jointed basaltic rock mass during tunnelling works. Conducting of multiple rounds of blasts for various civil excavations in a railway tunnel imparted repeated loading on rock mass of sidewall and roof of the tunnel. The blast induced damage was assessed by using vibration attenuation equations of charge weight scaling law and measured by borehole extensometers and borehole camera. Ground vibrations of each blasting round were also monitored by triaxial geophones installed near the borehole extensometers. The peak particle velocity ( V max) observations and plastic deformations from borehole extensometers were used to develop a site specific damage model. The study reveals that repeated dynamic loading imparted on the exposed tunnel from subsequent blasts, in the vicinity, resulted in rock mass damage at lesser vibration levels than the critical peak particle velocity ( V cr). It was found that, the repeated blast loading resulted in the near-field damage due to high frequency waves and far-field damage due to low frequency waves. The far field damage, after 45–50 occurrences of blast loading, was up to 55% of the near-field damage in basaltic rock mass. The findings of the study clearly indicate that the phenomena of repeated blasting with respect to number of cycles of loading should be taken into consideration for proper assessment of blast induced damage in underground excavations.

Attenuation relations of peak ground acceleration and velocity in the Southern Dead Sea Transform region

Using the recorded earthquake strong ground motion, the attenuation of peak ground acceleration (PGA) and peak ground velocity (PGV) are derived in the southern Dead Sea Transform region. The expected values of strong motion parameters from future earthquakes are estimated from attenuation equations, which are determined by regression analysis on real accelerograms. In this study, the method of Joyner and Boor [Bull Seismol Soc Am 71(6):2011–2038, 1981] was selected to produce the attenuation model for the southern Dead Sea Transform region. The dataset for PGA consists of 57 recordings from 30 earthquakes and for PGV 26 recordings from 19 earthquakes. The attenuation relations developed in this study are proposed as replacement for former probabilistic relations that have been used for a variety of earthquake engineering applications. The comparison between the derived PGA relations from this study with the former relations clearly shows significant lower values than the other relations.

Protein adsorption dynamics in cation-exchange chromatography quantitatively studied by confocal laser scanning microscopy

A self-contained research system based on the technique of confocal laser scanning microscopy (CLSM) was put up to quantitatively analyze the dynamics of protein adsorption to porous cation exchanger by mathematical modeling. Bovine serum albumin adsorption to the cation exchanger SP Sepharose FF was performed by batch adsorption and micro-flow cell in which protein concentration in single absorbent was visualized by CLSM. The effects of ionic strength and the protein concentration in liquid phase (50 mmol/L acetate buffer, pH 5.0) on the adsorption dynamics were examined. The intraparticle concentration profile data experimentally obtained from CLSM were quantitatively analyzed by three diffusive mass transfer models (i.e., pore diffusion, surface diffusion and Maxwell–Stefan models (MSM)) in virtue of the attenuation equation for the CLSM visualization developed earlier. The nuance between the model simulations and experimental results of the developing protein distribution in a single adsorbent particle could thus be found out. Without salt addition to the buffer, the adsorption isotherm was strongly favorable, and the pore diffusion model (PorDM) and MSM gave similarly good simulations of the experiments, whereas the surface diffusion model was unreasonable in the model presumption. Moreover, it was observed that the experimentally obtained adsorption front was relative flatter as compared with the calculated results from the PorDM, which implied the possible existence of surface diffusion. With increasing salt concentration, the simulations became to deviate from the experiments. Especially, when the salt concentration approached 50 mmol/L, all the three mass transfer models could hardly give good simulation of the experiment. This was considered due to the difference in adsorption behavior between the fluorescence labeled and unlabeled proteins therein.

The Attenuation of Seismic Intensity in Italy, Part I: Theoretical and Empirical Backgrounds

Abstract We critically analyze the results on seismic intensity attenuation in Italy derived by Albarello and D’Amico (2004) and Gasperini (2001). We demonstrate that, due to the inadequacy of certain underlying assumptions, the empirical relationships determined in those studies did not best reproduce the decay of intensity as the distance from the source increases. We reconsidered some of the relevant concepts and assumptions used in these intensity-attenuation studies (macroseismic epicenter, epicentral intensity, data completeness) to suggest some useful recipes for obtaining unbiased estimates. In particular, we suggest that (1) data for distances from the source at which an intensity below the limit of diffuse perceptibility (≤IV) is expected should be excluded from attenuation computations because such data are clearly incomplete, (2) attenuation equations that include a term proportional to the epicentral intensity I 0 with a coefficient different from 1.0 must not be used because they imply a variable offset between I 0 and the intensity expected at the epicenter, and (3) epicentral intensities must be recomputed consistently with the attenuation equation because those reported by the Italian catalog do not generally correspond with the intensity predicted at the epicenter by the attenuation relationships so far proposed. Following these suggestions produces a significant reduction in the standard deviation of the model that might lead to a corresponding reduction of the estimates of seismic hazard.

The Attenuation of Seismic Intensity in Italy, Part II: Modeling and Validation

Abstract Several different attenuation models have recently been proposed for the Italian region to characterize the decay of macroseismic intensity with the distance from the source. The significant scatter between these relationships and some significant drawbacks that seem to characterize previous approaches (described in a companion article by Pasolini et al. , 2008) suggest that the problem needs to be reconsidered. As a first step toward more detailed analyses in the future, this study aimed at developing an isotropic attenuation relationship for the Italian area. Because this attenuation relationship has to be used primarily in probabilistic seismic hazard assessment, major attention was given to evaluating the attenuation relationship in its complete probabilistic form. Another important aspect of this study was the preliminary evaluation of the intrinsic (i.e., independent of the specific attenuation relationship to be used) scattering of data, which represents the lowest threshold for the residual variance that cannot be explained by the attenuation relationship. Furthermore, the peculiar formal features of intensity data and relevant uncertainties were considered carefully. To reduce possible biases, the completeness of the available database was checked and a suitable data selection procedure was applied. Since epicentral intensity cannot be defined unambiguously from the experimental point of view, the attenuation relationship was scaled with a new variable that is more representative of the earthquake dimension. Several criteria were considered when evaluating competing attenuation formulas (explained variance, Bayesian information criteria, Akaike information criteria, etc.). Statistical uncertainty about empirical parameters was evaluated by using standard approaches and bootstrap simulations. The performance of the selected relationship with respect to a control sample was analyzed by using a distribution-free approach. The resulting equation for the expected intensity I at a site located at epicentral distance R is where , h =(3.91±0.27) km, and I E is the average expected intensity at the epicenter for a given earthquake that can be computed from the intensity data (when available) or by using empirical relationships with the moment magnitude M w or the epicentral intensity I 0 reported by the Italian seismic catalog Comparison of the model standard deviation (S.D.) (0.69 intensity degrees) with the intrinsic one (0.62) indicates that this attenuation equation is not far from being optimal.

Ground-Motion Attenuation Relationships for Subduction-Zone Earthquakes in Northeastern Taiwan

Subduction zone earthquakes have not been taken into special consid- eration in most previous probabilistic seismic hazard analyses (PSHA) in Taiwan. However, they may be critical to properly analyze the earthquake hazard in metro- politan Taipei, so they need to be studied. Strong-motion data from subduction zone earthquakes, of both interface and intraslab types, obtained by the TSMIP and SMART1 arrays in northeastern Taiwan, are used to establish the attenuation equa- tions for peak ground acceleration (PGA) and response spectral acceleration (SA). The resultant PGA and SA attenuation equations include two site classes and two earth- quake source types. The ground-motion values predicted by these attenuation equa- tions are higher than those obtained from the crustal earthquake attenuation equations previously used in Taiwan but are lower than those predicted by the attenuation equa- tions for worldwide subduction zone earthquakes.

Reply to "Comment on 'Why Do Modern Probabilistic Seismic-Hazard Analyses Often Lead to Increased Hazard Estimates?' by Julian J. Bommer and Norman A. Abrahamson" by Zhenming Wang and Mai Zhou

As with previous discussions submitted by the lead author of this comment (Wang, 2005), Wang and Zhou (2007) are not really commenting directly on the contents of our review article (Bommer and Abrahamson, 2006) but are using the opportunity to present a fundamental objection to probabilistic seismic-hazard analysis (PSHA). However, because the objective of our article was to clarify a fundamental aspect of PSHA that is frequently handled incorrectly in current practice, we welcome the opportunity to also respond to the arguments put forward in this comment. These arguments against the basic formulation of PSHA are likely to appear in print somewhere at some point, and we believe it is useful to explain why they are erroneous. Before addressing the core argument of Wang and Zhou (2007), it may be useful to clarify the issue of the dependence of the ground-motion variability on magnitude and distance. Most ground-motion prediction (attenuation) equations produced up until about 10 years ago modeled the variability as being homoscedastic, which simply means that the standard deviation ( σ ) of the lognormal residuals is constant for all values of magnitude and distance. The variation of σ with magnitude—called heteroscedastic variability—is discussed by Youngs et al. (1995) and has been found in many strong-motion prediction equations (e.g., Abrahamson and Silva, 1997; Campbell, 1997; Campbell and Bozorgnia, 2003; Ambraseys et al. , 2005; Akkar and Bommer, 2007a). Whether or not the apparent dependence of σ on magnitude is genuine or an artefact of the datasets that have been used for regressions, however, is not the main issue …

Optics-intrinsic double-circle phenomenon in protein adsorption visualized by confocal laser scanning microscopy

Confocal laser scanning microscopy (CLSM) has been introduced in the research of chromatographic adsorption and the technique provides a direct and noninvasive way to measure and characterize intraparticle concentration distributions of proteins on a single particle level. In this work, an optics-intrinsic double-circle phenomenon that occurs in protein adsorption visualized by CLSM is exhibited and its optical mechanism is reasonably explained by an evolutive version of the attenuation equation. The time course of intraparticle fluorescence intensity profiles obtained from CLSM (even the double-circle phenomenon) in this research is vividly reproduced by model simulation, which takes into account the light attenuation by combining the attenuation equation with an effective pore diffusion model.

A neural network approach for attenuation relationships: An application using strong ground motion data from Turkey

This paper presents an application of neural network approach for the prediction of peak ground acceleration (PGA) using the strong motion data from Turkey, as a soft computing technique to remove uncertainties in attenuation equations. A training algorithm based on the Fletcher–Reeves conjugate gradient back-propagation was developed and employed for three sample sets of strong ground motion. The input variables in the constructed artificial neural network (ANN) model were the magnitude, the source-to-site distance and the site conditions, and the output was the PGA. The generalization capability of ANN algorithms was tested with the same training data. To demonstrate the authenticity of this approach, the network predictions were compared with the ones from regressions for the corresponding attenuation equations. The results indicated that the fitting between the predicted PGA values by the networks and the observed ones yielded high correlation coefficients ( R 2). In addition, comparisons of the correlations by the ANN and the regression method showed that the ANN approach performed better than the regression. Even though the developed ANN models suffered from optimal configuration about the generalization capability, they can be conservatively used to well understand the influence of input parameters for the PGA predictions.

Cracking effect on gamma-ray shielding performance in concrete structure

Owing to its low price and good shielding performance, concrete sees wide use as a radiation shielding material. In concrete structures, cracks occur due to thermal stress, hydration heat, weather, load and other reasons, and shielding performance changes according to the crack width. However, there are no design criteria providing the allowable crack size for shielding. This paper presents the design for a measuring instrument for quantifying the effect of cracks on shielding performance in a concrete body. The correlation between crack width and shielding performance is then deduced through experiments. A measuring system with a collimator is designed and fabricated and a concrete sample with collinear cracking is designed. The surface dose rate increased logarithmically according to the increase in crack width. The present experiment results are used to formulate an attenuation equation for gamma rays in a concrete structure with collinear cracks. The results of this study may be used for developing standards for radiological safety in shielding structures, especially in relation to the shielding margin.

Seismic Hazard Assessment of the NW Himalayan Fold-and-Thrust Belt, Pakistan, Using Probabilistic Approach

The Seismic Hazard Assessment (SHA) based on probabilistic approach has been carried out for the entire seismically active NW Himalayan Fold and Thrust Belt in Pakistan. Additional information in the form of earthquake catalog, delineation of 41 active faults in a structural map, their relationship to the seismicity, and establishment of seismotectonic zones has also been undertaken. From the distribution of the 813 events within the study area, it appears that seismicity (≥4.0 Mw) is associated with both surface and blind faults. The clustering of events in specific parts along the surface faults shows that some fault segments, especially in the hinterland zone, are more active. In parts of the active deformational front, like the Salt Range, southern Potwar and Bannu, lesser seismic activity (≥4.0 Mw) could be due to damping effect of the thick Precambrian salt. A majority of the earthquakes (86%) range in magnitude from 4.0 to 4.9 Mw, followed by 107 events (13%) ranging from 5.0 to 5.9 Mw. The remaining 1% range from 6.0 to 6.7 Mw. There is a predominance of shallow seismicity (<50 km focal depth). Larger magnitudes events are more in the hinterland zone. In contrast, based on distribution of 683 (≥4.0 Mw) events, a deeper level of seismicity (50 to 200 km) prevails especially in the adjoining Hindukush Range of Afghanistan. Four seismotectonic zones have been established in the area. The b value is highest for the Peshawar-Hazara Seismic Zone (PHSZ) at 1.27, followed by 1.12 for the Surghar-Kurram Seismic Zone (SKSZ). The Swat-Astor Seismic Zone (SASZ) and Kohat-Potwar-Salt Range Seismic Zone (KPSZ) have b values of 0.99 and 1.03, respectively, thereby indicating the occurrence of more events of relatively higher magnitude as compared to the other two zones. The mean activity rate of the earthquakes (λ) ranges from 4.26 to 1.73. In decreasing order, the values are 4.26, 2.62, 2.07, and 1.73 for PHSZ, SASZ, KPSZ, and SKSZ, respectively. Using four regression relationships, the maximum potential magnitude (m1) has been determined for the 4 Quaternary faults. The highest value within each seismic zone represents its m1. Our calculations show that m1 is 7.8 in the hinterland (SASZ and PHSZ) and 7.4 in the foreland part (KPSZ and SKSZ). SHA, incorporating probabilistic approach, has been undertaken at 10 sites, along with disaggregation at the assigned amplitude of 0.2g. Pakistan does not have an attenuation equation of its own. The two equations of Ambraseys et al. (1996) and Boore et al. (1997) have been used and the results obtained using the equation of Boore et al. (1997) have been preferred. In the Probabilistic seismic hazard assessment (PSHA), the PGA values with 10% probability of exceedance in the 50 years, i.e., the return period of 475, have been determined using the EZ-FRISK (6.2 beta version) software. Best-estimated seismic hazard parameters (λ, m1, m0, and the β value) of the four seismic zones were used as the input. Results were generated in the form of total hazard curves. Values obtained range from 0.08g (for Bannu) to 0.21g (for Malakand and Kohat). For the other seven sites they are: Astore (0.082g), Kaghan (0.12g), Muzaffarabad (0.13g), Islamabad and Peshawar (0.15g), Talagang (0.16g), and Mangla (0.18g). High population density and more poorly constructed structures in Rawalpindi (twin city of Islamabad) and Peshawar make them more hazardous.

Alternative Models of Seismic Hazard Evaluation along the Jordan–Dead Sea Transform

Three models were used to produce three probabilistic hazard maps for the Jordan–Dead Sea transform (DST). No seismic source zones were proposed. Models I and II are based on spatially smoothed historical and instrumentally recorded earthquakes. Model I used the data with magnitudes greater than 3.0 for the time period 1900 to 2003, while Model II used data with the magnitude range between 5.0 and 7.0 for the time period 2100 B.C. to A.D. 2003. Model III is the weighted model that is based on characteristic earthquakes that occurred along each major fault in the last ∼4,100 years. To assess the peak ground acceleration (PGA), three different attenuation equations were used. The resulting hazard maps represent 10% probability of being exceeded in 50 years, which corresponds to a return period of 475 years. The maximum PGA value was 350 cm/sec2 for the northernmost part of the DST, namely, between latitudes 35.5° and 36.5° N, and the southwestern part of Cyprus. In the regions of maximum expected ground motion, there is general agreement between the results of this study and those of previous studies that used the seismic source zones. However, peak ground accelerations predicted in this study are typically 10–20% less than those of previous studies. We believe this study represents an improvement on prior seismic hazard evaluations for the region. In addition to the updated input data, we believe that, by integrating three models, a more robust estimate of the hazard is provided.

CATHODIC PROTECTION DESIGN FOR COMPLEX BURIED CONDUCTOR NETWORKS

This paper deals with the design of cathodic protection for complex buried conductor networks, whereas the use of classical methods like the attenuation equations method for calculation of the cathodic protection potentials distribution might be a problem. A suitable approach is based on a discrete net model that allows facing the problem through the traditional equations of linear electrical networks. This method, successfully tested in several situations, was initially proposed using a conductance-based net model. The present paper improves on this method, using simple numerical examples to demonstrate that the dual net representation through a resistance-based model allows an easier and more systematic solution of typical cathodic protection problems, offering to the designer direct insight into how control variables (such as placement and loading of protection feeders) affect the objective function (voltage profile or total current injection).

Ground motion environment of the Los Angeles region

AbstractThis paper reviews aspects of fault geometry and geological structure that cause spatial variations in the level of ground motions expected from large‐scenario earthquakes. These conditions include style of faulting, differences between surface faulting and buried faulting earthquakes, rupture directivity effects, basin effects and basin edge effects. These effects are illustrated in large‐scale ground motion simulations of scenario earthquakes on the Puente Hills Blind Thrust and the Southern San Andreas fault. The impact of these effects on probabilistic seismic hazard is also explored by means of CyberShake calculations in which the ground motions at a given site from a very large number of earthquake scenarios are represented by simulated time histories in place of conventional ground motion attenuation equations used in probabilistic seismic hazard analysis. We find that the seismic hazard estimates are quite similar in some locations, such as downtown Los Angeles, but quite different at others, such as Whittier. These differences are attributable to the coupling of rupture directivity and basin effects that are present in the CyberShake and TeraShake calculations but not in the conventional attenuation relations. Copyright © 2006 John Wiley &amp; Sons. Ltd.

A probabilistic derivation of gamma-ray attenuation and application: Bayesian mass estimation with a low count spectrum

This paper presents an intuitive derivation of the source and absorber factors in a slab geometry formulation of γ -ray emissions incident on a detector. Using the attenuation equations, an application to mass estimation from a passively observed, low count spectrum is developed for sources with γ -ray emissions. Propagation of error provides a confidence interval on the mass estimate. The developed methods are applied to experimental spectra from a known mass of plutonium 239 oxide. The proposed estimation method has potential in national security applications where the geometry of attenuation materials is unknown and there are time constraints on the acquisition of a spectrum. In these application settings, the first-order mass estimate developed in this paper is sufficiently accurate.

Modeling and simulation of protein uptake in cation exchanger visualized by confocal laser scanning microscopy

Confocal laser scanning microscopy (CLSM) has been extensively applied in the area of protein chromatography to investigate the uptake mechanism of protein in adsorbents. However, due to the light attenuation in the deeper layers of a specimen, quantitative analysis using CLSM data is still far from reality. In this work, an attenuation equation for describing the darkening of the CLSM image in the deeper scanning layers was developed. Bovine serum albumin (BSA) adsorption to SP Sepharose FF was performed by batch adsorption and micro-column chromatography on which protein concentration in single absorbents were visualized by CLSM. The parameters in the equation were estimated by fitting it to the fluorescence intensity profiles obtained at adsorption equilibrium, and then the equation was used to simulate the effect caused by the light scattering and absorption. CLSM analysis demonstrated that BSA adsorption to SP Sepharose FF followed the shrinking core pattern and was predicted reasonably well by the pore diffusion model in combination with the attenuation equation. By comparison of the CLSM data with the simulations, it shows that the attenuation equation was useful to demonstrate the validity of an intraparticle mass transport model for the estimation of intraparticle protein concentration profiles.

Introduction to Dr. Iwasaki’s Paper Entitled “Response Analysis of Civil Engineering Structures Subjected to Earthquake Motions”

Seismic design of Japanese bridges started in 1925, triggered by the extensive damage of the 1923 Kanto earthquake. "Drafted Structural Details of Road Structures," issued by Japan's Ministry of the Interior in 1925, recommended the use of static seismic analysis based on working stress design, which was used for a long time. "Design Specifications of Steel Bridges," issued by the Japan Road AssoCiation in 1964, was an important code used for design of a number of bridges during restoration after World War II and the early high economic growth periods that followed. There was no independent seismic design code in those days, so only limited descriptions were provided for seismic design, e.g., pages in the code related to seismic design numbered only 2 or 3, and seismic knowledge was limited. Most bridges damaged in the 1995 Kobe earthquake were designed based on this code. Extensive damage in the 1964 Niigata earthquake initiated intensified research on the structural response and seismic design of bridges. Accomplishments of research were reflected in the 1971 "Guide Specifications on Seismic Design of Bridges" (Japan Road Association), the first design guidelines focusing on the seismic design of bridges. Pages of the main text and explanations related to seismic design increased to 30, and included the natural period dependent lateral seismic coefficient and preliminary evaluation of soil liquefaction assessment and unseating prevention devices. This was the first time that preliminary liquefaction assessment and unseating prevention devices innovated by Japanese bridge engineers were included in bridge codes. The 1971 Guide Specification of Seismic Design of Bridges was compiled with other design codes and issued in 1980 as "Part V Seismic Design" of "Design Specifications of Highway Bridges" (Japan Road Association). Assessment of soil liquefaction based on FL was introduced in Part V, but other parts remained almost unchanged. Part V was completely revised in 1990 to include (1) new static analysis evaluating lateral force in continuous bridges based on the stiffness of superstructures and substructures, (2) safety evaluation (level 2) ground motion for the design of reinforced concrete columns, and (3) design response spectra and design-spectra-compatible ground acceleration for dynamic response analysis. This was the first in Japan to include safety evaluation ground motion and static design for ductility evaluation of bridge columns. Pages on code related to seismic design increased to 96 greatly enhanced as a modern seismic design code. Based on the extensive damage sustained in the 1995 Kobe earthquake, Part V on seismic design was further revised in 1996 and 2002 to include lessons learned from this damage. Pages of code related to seismic design increased to 227 in the 1996 code and 280 in the 2002 code. Figure 1 shows the increase in the number of pages related to seismic design. Extensive improvement was conducted in 1990 and 1996. Although we have had over 80 years in experience of seismic bridge design, only in the last 15 years has seismic bridge design been enhanced to include modern requirements. Codes before the 1971 Guide Specification and the 1980 Part V on seismic design had insufficient scientific knowledge, although they were used for design in a number of bridges. The paper by Dr. Iwasaki has contributed much to establishing modern seismic design codes for bridges. His contributions include, but are not limited to, the clarification of dynamic response characteristics of bridges based on extensive field measurements, the deployment of strong motion recording networks, the development of soil liquefaction evaluation based on FL, and the development of ground motion attenuation equations. All of his activities and research helped enhance seismic design codes for bridges in Japan.