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PREdiction of NOn-LINear soil behavior (PRENOLIN) is an international benchmark aiming to test multiple numerical simulation codes that are capable of predicting nonlinear seismic site response with various constitutive models. One of the objectives of this project is the assessment of the uncertainties associated with nonlinear simulation of 1D site effects. A first verification phase (i.e., comparison between numerical codes on simple idealistic cases) will be followed by a validation phase, comparing the predictions of such numerical estimations with actual strongmotion recordings obtained at well-known sites. The benchmark presently involves 21 teams and 23 different computational codes. We present here the main results of the verification phase dealing with simple cases. Three different idealized soil profiles were tested over a wide range of shear strains with different input motions and different boundary conditions at the sediment/bedrock interface. A first iteration focusing on the elastic and viscoelastic cases was proved to be useful to ensure a common understanding and to identify numerical issues before pursuing the nonlinear modeling. Besides minor mistakes in the implementation of input parameters and output units, the initial discrepancies between the numerical results can be attributed to (1) different understanding of the expression “input motion” in different communities, and (2) different implementations of material damping and possible numerical energy dissipation. The second round of computations thus allowed a convergence of all teams to the Haskell–Thomson analytical solution in elastic and viscoelastic cases. For nonlinear computations, we investigate the epistemic uncertainties related only to wave propagation modeling using different nonlinear constitutive models. Such epistemic uncertainties are shown to increase with the strain level and to reach values around 0.2 (log10 scale) for a peak ground acceleration of 5 m=s2 at the base of the soil column, which may be reduced by almost 50% when the various constitutive models used the same shear strength and damping implementation.

Several aspects of the seismic response of groups containing nonvertical piles are studied, including the lateral pile- head stiffnesses, the 'kinematic' pile deformation, and the 'inertial' soil-pile-structure response. A key goal is to explore the conditions under which the presence of batter piles is beneficial, indifferent, or detrimental. Parametric analyses are carried out using three-dimensional finite-element modeling, assuming elastic behavior of soil, piles, and superstructure. The model is first used to obtain the lateral stiffnesses of single batter piles and to show that its results converge to the available solutions from the literature. Then, real accelerograms covering a broad range of frequency characteristics are employed as base excitation of simple fixed-head two-pile group configurations, embedded in homogeneous, inhomogeneous, and layered soil profiles, while supporting very tall or very short structures. Five pile inclinations are considered while the corresponding vertical-pile group results serve as reference. It is found that in purely kinematic seismic loading, batter piles tend to confirm their negative reputation, as had also been found recently for a group subjected to static horizontal ground deformation. However, the total (kinematic plus inertial) response of structural systems founded on groups of batter piles offers many reasons for optimism. Batter piles may indeed be beneficial (or detrimental) depending on, among other parameters, the relative size of the overturning moment versus the shear force transmitted onto them from the superstructure. DOI: 10.1061/(ASCE)GT.1943-5606.0000337 CE Database subject headings: Piles; Lateral loads; Seismic effects; Numerical models; Kinematics; Soil-structure interactions; Elasticity. Author keywords: Batter piles; Lateral loading; Seismic response; Numerical modeling; Kinematic response; Inertial response; Soil-structure interaction.

A numerical study is presented for a rigid block supported through a frictional contact surface on a horizontal or an inclined plane, and subjected to horizontal or slope-parallel excitation. The latter is described with idealized pulses and near-fault seismic records strongly influenced by forward-directivity or fling-step effects (from Northridge, Kobe, Kocaeli, Chi-Chi, Aegion). In addition to the well known dependence of the resulting block slippage on variables such as the peak base velocity, the peak base acceleration, and the critical acceleration ratio, our study has consistently and repeatedly revealed a profound sensitivity of both maximum and residual slippage: (1) on the sequence and even the details of the pulses contained in the excitation and (2) on the direction (+ or -) in which the shaking of the inclined plane is imposed. By contrast, the slippage is not affected to any measurable degree by even the strongest vertical components of the accelerograms. Moreover, the slippage from a specific record may often be poorly correlated with its Arias intensity. These findings may contradict some of the prevailing beliefs that emanate from statistical correlation studies. The upper-bound sliding displacements from near-fault excitations may substantially exceed the values obtained from some of the currently available design charts. DOI: 10.1061/(ASCE)GT.1943-5606.0000174 CE Database subject headings: Sliding: Seismic effects: Ground motion: Symmetry: Asymmetry.

Observations after earthquakes where surface fault ruptures crossed engineering facilities reveal that some structures survived the rupture almost unscathed. In some cases, the rupture path appears to divert, 'avoiding' the structure. Such observations point to an interaction between the propagating rupture, the soil, and the foundation. This paper (i) develops a two-step nonlinear finite-element methodology to study rupture propagation and its interaction with strip foundations; (ii) provides validation through successful Class 'A' predictions of centrifuge model tests; and (iii) conducts a parameter study on the interaction of strip foundations with normal fault ruptures. It is shown that a heavily loaded foundation can substantially divert the rupture path, which may avoid outcropping underneath the foundation. The latter undergoes rigid body rotation, often detaching from the soil. Its distress arises mainly from the ensuing loss of support that takes place either at the edges or around its center. The average pressure q on the foundation largely dictates the width of such unsupported spans. Increasing q decreases the unsupported width, reducing foundation distress. The role of q i s dual: (1) it compresses the soil, 'flattening' fault-induced surface 'anomalies'; and (2) it changes the stress field underneath the foundation, facilitating rupture diversion. However, even if the rupture is diverted, the foundation may undergo significant stressing, depending on its position relative to the fault outcrop. CE Database subject headings: Geological faults; Soil-structure interaction; Finite element method; Centrifuge models; Seismic effects; Foundations.

The three notorious earthquakes of 1999 in Turkey (Kocaeli and Duzce) and Taiwan (Chi-Chi), having offered numerous examples of surface fault rupturing underneath civil engineering structures, prompted increased interest in the subject. This paper develops a nonlinear finite-element methodology to study dip-slip ('normal' and 'reverse') fault rupture propagation through sand. The procedure is verified through successful Class A predictions of four centrifuge model tests. The validated methodology is then utilized in a parametric study of fault rupture propagation through sand. Emphasis is given to results of engineering significance, such as: (1) the location of fault outcropping; (2) the vertical displacement profile of the ground surface; and (3) the minimum fault offset at bedrock necessary for the rupture to reach the ground surface. The analysis shows that dip-slip faults refract at the soil-rock interface, initially increasing in dip. Normal faults may keep increasing their dip as they approach the ground surface, as a function of the peak friction angle [[phi].sub.p] and the angle of dilation [[psi].sub.p]. In contrast, reverse faults tend to decrease in dip, as they emerge on the ground surface. For small values of the base fault offset, h, relative to the soil thickness, H, a dip-slip rupture cannot propagate all the way to the surface. The h/H ratio required for outcropping is an increasing function of soil 'ductility.' Reverse faults require significantly higher h/H to outcrop, compared to normal faults. When the rupture outcrops, the height of the fault scrap, s, also depends on soil ductility. CE Database subject headings: Finite element methodology; Predictions; Centrifuge model; Earthquakes; Shear deformation; Scale effect.

A simple integrated procedure to analyze the problem of soil-pile-foundation-superstructure interaction is presented. The procedure combines the available theories for the computation of the dynamic impedances and kinematic-seismic response factors of pile foundations with a simple six-degree-of-freedom structural model. The procedure is used to predict the response of the Painter Street Bridge located at Rio Dell, California, which wa excited by the 1992 Petrolia earthquake. The predicted response with the proposed procedure is in very good agreement with recorded data, and the significance of considering the frequency dependent pile-foundation impedances in predicting the superstructure response is demonstrated.

There is substantial evidence that the city of Kirovakan, Armenia, despite its proximity (10 km) to the fault, experienced in general very small intensity of shaking during the 1988 earthquake. Moreover, the distribution of damage in the city was very nonuniform. In this paper, first, arguments are presented to show that seismological and geologic factors, relating to the generation and transmission of the seismic waves, could explain the unusually weak base excitation in Kirovakan. Then, the results of one-dimensional (1D) wave-propagation analysis, using soil profiles with field and laboratory measured parameters, are presented to explain the damage statistics in five zones into which the city was divided. 1D analyses of wave amplification in soil are found to provide adequate answers for zones where the underlying soils consist of less than 30 m dense gravelly sands and stiff clays. However, such analyses fail to explain the disproportionately large degree of damage observed only in one region, where soil profile constitutes a triangular sedimentary basin with maximum soil depth of about 150 m and width-to-depth ratio of about 5. A simplified three-dimensional wave-propagation analysis of the 'valley' effects on ground-surface motions, provides a better explanation of the observed damage.

This is the first in a sequence of five papers dealing with engineering aspects of the surface-wave magnitude M(sub s) approximately equal to 6.8, 1988 Armenia earthquake, the devastating effects of which are still being felt in Armenia. Although the central theme of our three-year study has been to assess the role of local soil conditions on the magnitude and geographic distribution of damage, we have come to recognize that a close link exists among seismological, geological, geotechnical, and structural aspects of the Armenia earthquake. Our field investigations and analysis of various geologic and engineering aspects of the earthquake have culminated in a series of five papers. This and the companion paper present mostly factual information pertaining to: (1) The mechanics of the fault and its surface breakout; (2) some potentially significant topographic, geologic, and geotechnical features; and (3) the statistics of damage in cities of Spitak, Leninakan (now called Kumayri), and Kirovakan, Armenia, correlated to geologic and soil profiles. In the third and fourth papers of this series, which will appear in a subsequent issue of the journal, theoretical analysis of soil amplification in Leninakan and Kirovakan are described. The fifth paper, also in a later issue of the journal, presents data and analysis of liquefaction-induced embankment failure case histories.

This is a companion paper dealing with engineering aspects of the surface-wave magnitude M(sub s) approximately equal to 6.8 1988 Armenia earthquake. The first paper, by the same writers and in the same journal issue, provides an overview of the seismological, geological, geotechnical, and structural aspects of the earthquake. The present paper offers building-damage statistics in the cities of Leninakan and Kirovakan, Armenia. These statistics are qualitatively correlated to the soil profiles to assess the potential importance of any soil amplification effects. The results indicate that in Leninakan, located in a very wide valley, the soil had some effect but could not have been solely responsible for the tremendous damage in the city. In Kirovakan, the soil profiles vary significantly within the city. Damage was primarily within a limited region where there is a valley filled with stiff clays and having width-to-maximum-depth ratio of approximately 5:1. In this region, 74% of the buildings collapsed or were heavily damaged. Two subsequent papers by the present writers, in the following month's issue of the journal, describe theoretical analyses of soil amplification in Leninakan and Kirovakan. The results of these analyses are used to determine if current state-of-practice procedures could explain the damage statistics and their local and geographic distribution described in the present paper.