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This paper quantified the seismic resilience (SR) of different bridge classes by performing three-dimensional advanced numerical simulations in Opensees. SR was calculated by performing the seismic resilience for recovery investments of bridge (SRRIB) methodology that is based on the quantification of the losses and the repair time. In particular, the probabilistic-based methodology developed by the Pacific Earthquake Engineering Research Center (PEER) was implemented to produce fragility curves by considering the longitudinal displacement of the deck as the reference parameter. The recovery process was modeled using a linear formulation due to the unavailability of information from past earthquakes. SR for the selected bridge classes was calculated in terms of the seismic intensities to be applied for decision-making procedures during pre- and postearthquake assessments. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for prioritising bridge retrofits within a regional road network subject to uncertain seismic hazard, using a technique that accounts for network performance while avoiding the combinatoric computational costs of exhaustive searches. Using global variance-based sensitivity analysis, a probabilistic ranking of bridges is determined according to how much their retrofit statuses influence the expected cost of the road network disruption. Bridges' total-order sensitivity (Sobol') indices are estimated with respect to the expected cost using the hybrid-point Monte Carlo approximation method. A bridge's total-order Sobol' index measures how much its retrofit status influences the variance of the expected cost of the road network performance and accounts for the effect of its interactions with other bridges' retrofit states. For 71 highway bridges in San Francisco, a retrofit strategy based on bridges' total-order Sobol' indices outperforms other heuristic strategies. The proposed method remains computationally tractable while accounting for the probabilistic nature of the seismic hazard, the uniqueness of individual bridges, network effects, and decision-makers' priorities. Because this method leverages existing risk assessment tools and models without imposing further assumptions, it should be extensible to other types of networks under different types of hazards and to other decision variables. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the 3D response of a slab supported by wobbling columns. The columns are not allowed neither to slide nor to roll out of their initial position. An analytical model is proposed, the equations of motion are derived, and they are solved numerically. The paper concludes that the addition of the slab makes the columns more stable. In fact, the system is almost equivalent to the response of a solitary column with the same aspect ratio yet larger size. However, it is also shown that the system is less stable than its planar counterpart and that planar analysis can only qualitatively describe the behavior of 3D structures. A case study shows that the concept could be used as a seismic isolation technique for bridges. However, more research need to be performed on defining proper intensity measures for uplifting structures, as it is shown that there is large record‐to‐record variability, even when intensity measures developed for rocking structures are used. [ABSTRACT FROM AUTHOR]

This paper presents an up-to-date state-of-the-art review on the behaviour of irregular bridges under seismic excitation. Although several characteristics and definitions may be applicable to the regularity of bridge structures, almost all the published literature referencing the term 'irregular bridge' focuses on a specific class of straight reinforced concrete (RC) bridge with unequal pier heights as the main source of irregularity along the bridge length. Several successive as well as interrupted research works on the subject have been reported during the last two decades. Among significant developments under continuous progress in this field, two main advancements can be recognised: ( a) the development of displacement-based design methodology; ( b) further understanding of the higher modes effects, which reflects the adequacy of different analysis methods for irregular bridges. However, a review of the literature reveals that works being actively conducted on this subject are still inadequate and hence deserve further attention in future research to gain a better awareness of the seismic performance of irregular bridges, in order to provide simply applicable and more definitive guidelines for actual design purposes. [ABSTRACT FROM AUTHOR]

Summary: The paper presents a computationally efficient algorithm to integrate a probabilistic, non‐Gaussian parameter estimation approach for nonlinear finite element models with the performance‐based earthquake engineering (PBEE) framework for accurate performance evaluations of instrumented civil infrastructures. The algorithm first utilizes a minimum variance framework to fuse predictions from a numerical model of a civil infrastructure with its measured behavior during a past earthquake to update the parameters of the numerical model that is, then, used for performance prediction of the civil infrastructure during future earthquakes. A nonproduct quadrature rule, based on the conjugate unscented transformation, forms an enabling tool to drive the computationally efficient model prediction, model‐data fusion, and performance evaluation. The algorithm is illustrated and validated on Meloland Road overpass, a heavily instrumented highway bridge in El Centro, CA, which experienced three moderate earthquake events in the past. The benefits of integrating measurement data into the PBEE framework are highlighted by comparing damage fragilities of and annual probabilities of damages to the bridge estimated using the presented algorithm with that estimated using the conventional PBEE approach. [ABSTRACT FROM AUTHOR]

Design of bridges for seismic effects has changed significantly since it was originally included in the AASHTO Standard Specifications for Highway Bridges (the standard specifications) as Division IA in 1991. In addition to design changes, the seismic hazard in many areas of the United States has changed significantly in the AASHTO LRFD Bridge Design Specifications (the LRFD specifications) based on a change in the return period of the design earthquake and seismological research. A new option for seismic design, the AASHTO Guide Specifications for LRFD Seismic Bridge Design (the guide specifications), has been published providing an alternative, displacement-based design procedure. This paper provides a case study of three existing bridges in Alabama designed according to the standard specifications. The seismic resisting system of the existing bridges was redesigned based on the guide specifications and the LRFD specifications. The paper explores the effect of changes in design procedures and seismic hazard on detailing of bridges in a moderate seismic zone. The two specifications are compared for the worst-case hazard in Alabama; i.e., Seismic Design Category B. The results demonstrate that using the guide specifications results in larger spacing of lateral reinforcing in the plastic hinge regions of substructure components and drilled shafts resulting in more economical designs. [ABSTRACT FROM AUTHOR]

Seismic resilience of structures and infrastructure systems is a fast developing concept in the field of disaster management, promoting communities that are resistant and quickly recoverable in case of an extreme event. In this contest, probabilistic seismic demand and fragility analyses are two key elements of the seismic resilience assessment in the majority of the proposed methodologies. Several techniques are available to calculate fragility curves for different types of structures. In particular, to assess the seismic performance of the regional transportation infrastructure, methods for the fragility curve estimation for entire classes of bridges are required. These methods usually rely on a set of assumptions, partially because of the limited information. Other assumptions were introduced at the time when computational resources were inadequate for a purely numerical approach and closed-form solutions were a convenient alternative. For instance, some of these popular assumptions are aimed at simplifying the model of the engineering demand. In this paper, a simulation-based methodology is proposed, to take advantage of the computational resources widely available today and avoid such assumptions on the demand. The resulting increase in accuracy is estimated on a typical class of bridges (multi-span simply supported). Most importantly, the quantitative impact of the assumptions is assessed in the context of a life-cycle loss estimation analysis and resilience analysis. The results show that some assumptions preserve an acceptable level of accuracy, but others introduce a considerable error in the fragility curves and, in turn, in the expected resilience and life-cycle losses of the structure. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Non-linear time-history analysis is the most reliable method to evaluate the responses of bridges subjected to seismic loads. Canadian Highway Bridge Design Code, American Association State Highway and Transportation Officials require using spectrum-compatible accelerograms for time-history analysis. This paper presents four methods for obtaining spectrum-compatible accelerograms for time-history analysis of bridges in eastern Canada where real earthquake records are lacking. Based on the procedure given by these methods, four sets of accelerograms were selected for the study, namely; scaled real accelerograms, modified real accelerograms, simulated accelerograms and artificial accelerograms. In order to determine the suitable type of accelerograms for the seismic analysis, two reinforced concrete bridges located in Montreal, Canada were examined. Based on the results obtained simulated accelerograms are recommended to conduct time-history analysis of bridges in eastern Canada [ABSTRACT FROM AUTHOR]

A quarter-scale, two-span reinforced concrete bridge was tested using the shake-table system at the University of Nevada, Reno. The shake-table tests were part of a multiuniversity, multidisciplinary project utilizing the network for earthquake engineering simulation, with the objective of investigating the effects of soil-foundation-structure interaction on bridges. This paper discusses the development and testing of the bridge model, and selected experimental results, including those that demonstrate the effects of incoherent motions and stiffness irregularities on the distribution of forces and deformations within the bridge system. Motion incoherency affected the asymmetric bridge response (planar torsion of the superstructure), but had little effect on the symmetric bridge response (center-of-mass displacement of the superstructure). These experimental findings are consistent with conclusions from numerical analyses conducted by other researchers. During a 2.0 g PGA earthquake excitation, numerous longitudinal bars buckled and fractured at a drift ratio between 5.5 and 7.9%. Despite the level of damage, detailing of the column transverse reinforcement according to NCHRP 12-49 guidelines provided sufficient column ductility to prevent collapse during a subsequent 1.4 g PGA earthquake excitation. [ABSTRACT FROM AUTHOR]

The objective of the work of this paper was to investigate analytically the feasibility and advantages of applying various combinations of steel jacket retrofit measures developed for single-column bent bridges to multicolumn bent bridges. To achieve the objective, an existing nonlinear dynamic bridge analysis program with elastic–perfectly plastic column behavior and a conventional hysteresis model was modified in order to include softening behavior from column damage and a more realistic hysteresis rule for cyclic loading. A 2D structural model of an actual bridge was used to evaluate column retrofitting measures by applying a typical seismic record. Both partial and full column retrofit strategies were shown to result in decreased maximum earthquake response and decreased plastic deformation of columns for the bridge bent compared to the case without retrofitting, but to varying degrees. However, for some partial retrofit strategies, the plastic hinge rotation at the unretrofitted columns was deemed to be unacceptable. Therefore, it was concluded that partial column retrofit strategies are viable only if combined with an evaluation of the ductility capacity of the bridge. [ABSTRACT FROM AUTHOR]

This paper assesses the seismic fragility of single degree of freedom rocking structures within a probabilistic framework. The focus is on slender rigid structures that exhibit negative stiffness during rocking. The analysis considers ground motions with near-fault characteristics, either solely coherent pulses or synthetic ground motions that include, in addition, a stochastic high-frequency component. The study offers normalized fragility curves that estimate the overturning tendency, as well as the peak response rotation of a rocking structure. It shows that the use of bivariate intensity measures (IMs) can lead to superior fragility curves compared with conventional univariate IMs. Regardless, the study advocates the use of dimensionless-orientationless IMs that offer an approximately 'universal' description of rocking behavior/fragility, a normalized description almost indifferent to the amplitude and the predominant frequency of the excitation or the size and the slenderness of the rocking structure. Importantly, the analysis unveils hidden order in rocking response. There exists a critical peak ground acceleration, below and above which, peak rocking response scales differently. In particular, when the structure does not overturn, the peak rotation follows approximately a biplanar pattern with respect to the intensity and the predominant frequency of the excitation. Finally, the analysis verifies that rocking overturning depends primarily on the velocity characteristics of the ground motion. [ABSTRACT FROM AUTHOR]

A new passive seismic response control device has been developed, fabricated, and tested by the authors and shown to be capable of producing negative stiffness via a purely mechanical mechanism, thus representing a new generation of seismic protection devices. Although the concept of negative stiffness may appear to be a reversal on the desired relationship between the force and displacement in structures (the desired relationship being that the product of restoring force and displacement is nonnegative), when implemented in parallel with a structure having positive stiffness, the combined system appears to have substantially reduced stiffness while remaining stable. Thus, there is an 'apparent weakening and softening' of the structure that results in reduced forces and increased displacements (where the weakening and softening is of a non-damaging nature in that it occurs in a seismic protection device rather than within the structural framing system). Any excessive displacement response can then be limited by incorporating a damping device in parallel with the negative stiffness device. The combination of negative stiffness and passive damping provides a large degree of control over the expected performance of the structure. In this paper, a numerical study is presented on the performance of a seismically isolated highway bridge model that is subjected to various strong earthquake ground motions. The Negative Stiffness Devices (NSDs) are described along with their hysteretic behavior as obtained from a series of cyclic tests wherein the tests were conducted using a modified design of the NSDs (modified for testing within the bridge model). Using the results from the cyclic tests, numerical simulations of the seismic response of the isolated bridge model were conducted for various configurations (with/without negative stiffness devices and/or viscous dampers). The results demonstrate that the addition of negative stiffness devices reduces the base shear substantially, while the deck displacement is limited to acceptable values. This assessment was conducted as part of a NEES (Network for Earthquake Engineering Simulation) project which included shaking table tests of a quarter-scale highway bridge model. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A large-scale, two-span bridge model constructed by assembling precast elements was tested under a series of bi-axial ground motions simulated on a shake table at the Earthquake Engineering Laboratory at the University of Nevada, Reno. The response of the bridge was estimated before the tests using a three-dimensional computational model developed in OpenSees software. After the tests, key measured seismic responses were compared to those predicted by the computational model to assess the modeling assumptions. Relatively large errors for the displacements, base shears, and hysteretic response of the bridge were observed. The influence of the earthquake loading, materials, connectivity of the precast elements, and boundary conditions in the computational model on the errors are discussed in this paper. Future modeling directions are proposed to reduce these errors. [ABSTRACT FROM AUTHOR]

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SUMMARY This paper is concerned with a widely studied problem-that of the identification of the modal characteristics of freeway overcrossings and other bridges, which response is interacting with their approaching embankments and their foundation. The study implements a sophisticated parameter estimation method known as the prediction error method and examines in detail the sensitivity of the modal characteristics (frequency and damping) of the bridge when the input signals are taken at the free field, at the approaching embankments and pile caps, and on the abutments and the pile caps. The findings of this case study on the Meloland Road Overcrossing with the prediction error method are compared with the results from past system identification studies and the results from finite element analyses, which examined in depth the contribution of the approaching embankments in the bridge response. The study concludes that despite the appreciable energy dissipation capability of the approaching embankments the concrete bridge structure, while interacting mechanically with the embankments, remains small. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Absratct: The Maule (Chile) earthquake of 27 February, 2010 has caused severe disruption and economic losses. With a magnitude of 8.8, it has been recorded as one of the largest earthquakes of the last century. The ground motion records from large subduction earthquakes, such as the Chile earthquake, are sparse. The number of accelerograms that recorded the strong ground motion was relatively few and only a few of these ground motions were released to engineering community. One of the objectives of this paper is to develop site specific ground motions that take into account the particular characteristics of this major earthquake. These are proposed to the engineering community as representative ground motions based on the best available data. The second objective of the paper is to investigate, using numerical tools, some typical failures observed in the engineered buildings and bridges. Although, in general engineered structures performed very well and the majority of failures, hence losses, were to non-engineered structures, some repeated deficiencies in structural design were observed. The developed hazard and site specific ground motions are used as inputs for inelastic dynamic analysis of advanced finite element building and bridge models. The results are processed to explain quantitatively the structural deficiencies observed in the field. [Copyright &y& Elsevier]

In this paper the seismic response of inelastic structures with unilateral contact is revisited with dimensional analysis. All physically realizable contact types are captured via a non-smooth complementarity approach. The implementation of formal dimensional analysis leads to a condensed presentation of the response and unveils remarkable order even though two different types of non-linearity coexist in the response: the boundary non-linearity of unilateral contact and the inelastic behaviour of the structure itself. It is shown that regardless the intensity and frequency content of the excitation, all response spectra become self-similar when expressed in the appropriate dimensionless terms. The proposed approach hinges upon the notion of the energetic length scale of an excitation which measures the persistence of ground shaking to impose deformation demands. Using the concept of persistency which is defined for excitations with or without distinct pulses, the response is scaled via meaningful novel intensity measures: the dimensionless gap and the dimensionless yield displacement. The study confirms that contact may have a different effect on the response displacements of inelastic structures depending on the spectral region. In adjacent inelastic structures, such as colliding buildings or interacting bridge segments, contact is likely to alter drastically the excitation frequencies' at which the system is most vulnerable. Finally, it is shown that the proposed approach yields maximum response displacements which correlate very well with the persistency of real earthquakes for a bridge system with considerably complex behaviour. [ABSTRACT FROM AUTHOR]

Several definitions have been used concerning structural regularity. A structure is considered here as regular, if its responses obtained from different well recognized analysis methods do not show significant differences. In this paper, the effects of the inclusion of higher modes on the response of a class of reinforced concrete viaducts with different degrees of irregularity have been investigated. The seismic responses of continuous span single-column-bent viaducts have been studied through the comparison of the results obtained from different pushover-based analysis methods. Commonly used single and multi-mode pushover-based analysis methods have been utilized and their corresponding results have been compared with the results obtained from simpler methods such as the so-called uniform load procedure, as well as the more sophisticated inelastic time history analysis methods. For the class of the bridges under consideration, those configurations for which the effects of the higher modes are considerable have been identified and categorized as irregular, for which the minimum analysis requirements have been indicated in order to achieve a reliable bridge response. In contrast, the conditions in which a configuration may be classified as regular have been demonstrated and the adequacy of the simplified methods for the analysis of such models has been examined. The regularity issue has been discussed initially based on an expression developed by other researchers. Another index has also been introduced here for the attainment of a more realistic representation of the structural particulars of such bridges consist with the analysis methods specified in the AASHTO Specifications. [ABSTRACT FROM AUTHOR]

Liquefaction-induced ground deformation has caused major damage to bridge and wharf structures in past earthquakes. Large lateral ground displacements may induce significant forces in the foundation and superstructure, which may lead to severe damage or even collapse. A performance-based earthquake engineering (PBEE) approach can provide an objective assessment of the likely seismic performance, so that agencies can evaluate bridge or wharf structures, compare retrofit strategies, and rank them within their overall system. In this paper, a probabilistic PBEE design procedure that incorporates findings from recent research on this problem is presented. The proposed approach can provide answers in terms that are meaningful to owners, such as expected repair costs and downtimes. The methodology is validated through its application to a well-documented case history. Results show that the proposed approach provides a good estimate of the seismic performance of pile-supported structures at sites with liquefaction-induced lateral displacement. [ABSTRACT FROM AUTHOR]

Rooted in structural dynamics theory, three approximate procedures for estimating seismic demands for bridges crossing fault-rupture zones and deforming into their inelastic range are presented: modal pushover analysis (MPA), linear dynamic analysis, and linear static analysis. These procedures estimate the total seismic demand by superposing peak values of quasi-static and dynamic parts. The peak quasi-static demand in all three procedures is computed by nonlinear static analysis of the bridge subjected to peak values of all support displacements applied simultaneously. In the MPA and the linear dynamic analysis procedures, the peak dynamic demand is estimated by nonlinear static (or pushover) analysis and linear static analysis, respectively, for forces corresponding to the most-dominant mode. In the linear static analysis procedure, the peak dynamic demand is estimated by linear static analysis of the bridge due to lateral forces appropriate for bridges crossing fault-rupture zones. The three approximate procedures are shown to provide estimates of seismic demands that are accurate enough to be useful for practical applications. The linear static analysis procedure, which is much simpler than the other two approximate procedures, is recommended for practical analysis of “ordinary” bridges because it eliminates the need for mode shapes and vibration periods of the bridge. [ABSTRACT FROM AUTHOR]

This paper describes the application of semiactive devices for controlling the earthquake response of two highway bridges of different cross sections and pier heights. Each of the bridges consists of a three-span continuous deck supported on the piers and abutments. Semiactive devices such as the magnetorheological damper, the variable friction damper and the variable stiffness device are considered as the control devices. These devices are inserted between the deck and piers or abutments of the isolated bridge. The semiactive device changes its properties according to the structural response and adds control forces to the system. Each pier supporting the bridge is modeled as a linear lumped mass system. The optimum parametric values of the semiactive dampers are evaluated and considered in analysis of the bridge. A comparative study is performed for different semi-active devices installed on the bridges under different seismic loadings in the longitudinal direction. The behaviors of the bridges with different semiactive isolation devices are compared with the corresponding nonisolated ones. The semiactive dampers are observed as an effective protective device in reducing the displacements of the isolation bridges as well as the base shear of the piers. [ABSTRACT FROM AUTHOR]

Analytical seismic responses of structures retrofitted using base isolation devices are investigated and the retrofit schemes are illustrated. The retrofitting of various important structures using seismic isolation technique by incorporation of the layers of isolators at suitable locations is studied. Three specific structures such as historical buildings, bridges, and liquid storage tanks are selected to investigate the effectiveness of the base isolation in seismic retrofitting. Different types of isolation devices, such as elastomeric bearings and sliding systems are evaluated for their performance in the retrofitting works. The response of the retrofitted structural system is obtained numerically by solving the governing equations of motion under different earthquakes and compared with the corresponding conventional structure without any retrofit measures, in order to investigate the effectiveness of base isolation in retrofitting of structures. It is observed that the seismic response of the retrofitted structures reduces significantly in comparison with the conventional structures depicting effectiveness of the retrofitting done through the base isolation technique. This paper also distinctively elaborates on the methods of construction in retrofitting works involving base isolation. [ABSTRACT FROM AUTHOR]

Public safety requires that bridges be designed for the entire spectrum of loading conditions that could result in failures. During the past decade, seismic bridge design has become oriented towards specific performance objectives by considering possible rates of earthquake occurrence over the design life of the structure. A geographic information system (GIS) methodology for establishing potential long-term seismic risk for bridges is described in this paper. The GIS graphical and computational capabilities to analyze spatially distributed problems are shown to be an ideal, powerful tool for establishing ground motions within the performance-based criteria of modern seismic bridge design. Sample outputs for the Eastern United States (EUS) are presented as an application. Seismic events in this area are infrequent; however, they can pose a serious threat, especially considering that many of the bridges in EUS were built before seismic design was required. There are many problems associated in determining ground motions in the EUS, including a scarcity of recorded data, incomplete knowledge of seismic wave propagation characteristics, and sometimes insufficient knowledge of geologic conditions. In spite of these difficulties, it is possible to arrive at a rational estimate of the seismic risk potential in a probabilistic manner, combining available information, assumptions, and uncertainties using a GIS environment. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present the impact of bridge retrofitting in the San Francisco Bay Area on direct loss reduction. For this purpose, the losses from the characteristic earthquakes on the San Andreas and Hayward faults due to ground shaking, landslide or liquefaction are estimated for pre- and post-retrofitted bridges. Bridge losses are computed using the fragility functions from HAZUS [ Earthquake Loss Estimation , Technical Manual, 1999 and the Boore et al . [ Seismic Research Letters , 1997, 687(1), 128–154] attenuation relationship for ground motions at bridge sites. Loss from liquefaction and landslides is also estimated using HAZUS. The replacement cost for each bridge is calculated using values obtained from the California Department of Transportation (Caltrans). The loss estimates show that the annual risk reduction due to retrofitting is about 15% for the San Andreas fault and 10% for the Hayward fault events. If all possible events are taken into consideration, these values are expected to further increase, demonstrating the benefit of retrofitting. [ABSTRACT FROM AUTHOR]

This paper evaluates the impact of newly recommended LRFD seismic design guidelines (NCHRP Project 12-49) on the seismic design of bridges on soft soils in New Jersey. Current LRFD provisions are mostly based on the Division I-A Seismic Design of the AASHTO Standard Specifications (1996). NCHRP Project 12-49 was initiated to address the inadequate performance of highway bridges in recent earthquakes and the deficiencies in the current seismic code and to develop comprehensive specifications for seismic design of bridges considering all aspects of the design process. The intent of the new specifications is to be nationally applicable with provisions for all seismic zones. Because of the several significant changes in the design criteria and approach provided in the new provisions, there are questions on how these new provisions will affect the design and performance of bridge in states in the eastern United States as well as the retrofit of existing bridges. There are also questions about the impact of new provisions on the design of abutments and retaining walls. Hence, there was a need to evaluate the impact of the new seismic design provisions proposed in NCHRP 12-49 on the seismic design and detailing of bridges in New Jersey and the eastern United States. Two examples were designed based on NCHRP 12-49 recommended guidelines and the current LRFD specifications showed that the soil site factors had a major effect on the design. Also the transverse reinforcement requirements in plastic hinge zones were higher in the new NCHRP 12-49 provisions for larger diameter columns with heavy reinforcement than those in the current AASHTO LRFD. [ABSTRACT FROM AUTHOR]

Rapid restoration of highway bridges under disruptive events is essential due to the significant socio-economic consequences resulting from bridge closure. Functional bridges enable the community's immediate response, other lifeline systems' recovery, and network accessibility. This study proposes a risk-based approach for the resilience assessment of bridge systems using the state-dependent restoration process. The semi-Markov process (SMP) is employed to model functionality restoration and subsequently bridge resilience. To this end, bridge resilience has been quantified as a measure of multi-state functionality restoration with respect to time. Unlike traditional performance-based earthquake engineering (PBEE), the proposed framework enables the functionality restoration of a system to be characterized as a state-dependent process. The Monte Carlo approach is used to simulate functionality restoration curves considering uncertainty associated with hazard intensity and corresponding state durations, or repair times. This paper evaluates the scenario-based resilience of the bridge under concurrent effects of earthquake and flood-induced scour hazards. In so doing, multi-state functionality and resilience for bridge cases with different scour depths (y s = 3 m and 6 m) are estimated using the SMP and PBEE approaches. The simulation-based results were then compared with the benchmark case without scour. Based on the multi-hazard resilience assessment, lower values of resilience index are obtained from scoured bridge cases compared to zero-scour condition. Finally, the results from the SMP are compared with the PBEE for a two-state bridge system. The proposed state-dependent stochastic framework can provide decision-makers with information to quantitatively assess and enhance bridge resilience in an integrated manner. [ABSTRACT FROM AUTHOR]

This paper investigates the elastic-plastic seismic behavior of long span cable-stayed steel bridges through the plane finite-element model. Both geometric and material nonlinearities are involved in the analysis. The geometric nonlinearities come from the stay cable sag effect, axial force-bending moment interaction, and large displacements. Material nonlinearity arises when the stiffening steel girder yields. The example bridge is a cable-stayed bridge with a central span length of 605 m. The seismic response analyses have been conducted from the deformed equilibrium configuration due to dead loads. Three strong earthquake records of the Great Hanshin earthquake of 1995 in Japan are used in the analysis. These earthquake records are input in the bridge longitudinal direction, vertical direction, and combined longitudinal and vertical directions. To evaluate the residual elastic-plastic seismic response, a new kind of seismic damage index called the maximum equivalent plastic strain ratio is proposed. The results show that the elastic-plastic effect tends to reduce the seismic response of long span cable-stayed steel bridges. The elastic and elastic-plastic seismic response behavior depends highly on the characteristics of input earthquake records. The earthquake record with the largest peak ground acceleration value does not necessarily induce the greatest elastic-plastic seismic damage. [ABSTRACT FROM AUTHOR]

Within the near-fault zone, ground motions are influenced by the rupture mechanism and directivity phenomena. Near-fault ground motions are of special interest in Earthquake Engineering, as they might result in large inelastic displacements of structures. In this paper, an investigation is presented concerning the effect of the directivity pulses inherent in near-fault ground motions on the inelastic response of a curved RC bridge, specifically Bridge G7 of Egnatia Highway in Greece. The analyses were performed for a sample of 90 near-fault seismic records. From each record, the first six pulses were extracted and simplified ‘pulse records’ were defined, composed of one or more (up to six) pulses. First, a pushover analysis was performed and, based on the derived yield acceleration corresponding to the bilinear representation of the capacity curve, each record was scaled to three intensity levels, corresponding to behavior factors q y = 2, 3 and 4. Non-linear time-history analyses were then performed for each original record and the related ‘pulse records’ using OpenSees. By comparing the results, conclusions were drawn on the significance of each pulse to the nonlinear response. To this end, the errors for several general and local response quantities were calculated. The results show that the maximum inelastic deformations occur for the ground motions for which the elastic fundamental period of the bridge is close to one half of the period of the predominant pulse. Also, in most cases, the maximum response for the original record could be adequately estimated by the response for the ‘pulse record’ consisted of only two (and in few cases of three) pulses, especially when the fundamental period of the bridge was in between the periods of these pulses. [ABSTRACT FROM AUTHOR]

A prominent challenge in performance-based earthquake engineering is to select a suitable set of ground motions records with which to perform probabilistic seismic assessment of structures. The most common approach for engineering purposes is to employ actual recordings of worldwide events, given that large earthquakes do not occur frequently hence regional recordings of such events are usually not widely available. To address this not that uncommon issue, regionally simulated ground motions using a stochastic finite-fault method have been proposed as an alternative to real records. This study aims to explore the use of simulated records through a stochastic finite-fault method in probabilistic seismic assessment frameworks for reinforced concrete bridges, when compared to using real records. Direct seismic losses for a case-study existing bridge and a bridge portfolio are estimated and compared, as the reference risk metric. Finally, the similarities between seismic demands, obtained using both real and simulated record sets, are quantified and discussed via statistical hypothesis testing, resulting fragility curves and expected annual losses. The results show how simulated records can be a promising alternative to real records, becoming particularly useful in the absence of available recorded ground motions with specific seismogenic features. [ABSTRACT FROM AUTHOR]

A method for the estimation of expected annual losses under seismic action, using a component-level approach, is proposed. The method follows the general steps of current Performance-Based Earthquake Engineering approaches and two distinct alternatives are evaluated depending on how the collapse cases are identified. Results are compared with a commonly implemented structure level approach, showing that the latter presents an upper bound in loss estimation. The accuracy of simplified structural analysis alternatives, such as nonlinear static procedures, is also evaluated. The method is found to be suitable for economic loss assessment under seismic hazards, producing performance measures easy to understand for different decision makers. [ABSTRACT FROM AUTHOR]

The prefabricated bridge with standard span have become the most widely used structure in the highway-net by advantage of its low cost, simple design and construction. However, study on seismic fragility of such bridges is rarely found yet. Taking service function as seismic fortification goal, this paper defines five levels of performance for typical multi-span bridges. The critical damage value for the bridge pier is put forward as the criteria of four kinds of pier damage limit states. Moreover, the method and procedure of seismic fragility analysis of highway bridges are presented, in which uncertainties of the primary structure materials and ground motion input are considered respectively. The seismic fragility analysis is conducted to obtain the bridge failure mode and damage probability. The fragility analysis for performance-based seismic design of highway bridges provides the theoretical basis for a seismic performance analysis and emergency preplan formulation in the highway-net. [ABSTRACT FROM AUTHOR]

In recent years, Italian legislator has underlined the necessity of a seismic risk evaluation for relevant and strategic buildings, in order to define proper strategies for seismic risk mitigation. Most of the bridges should be considered as strategic structures for the importance of guaranteeing road connections, and therefore it is necessary to estimate the potential consequences in case of an earthquake. If a large amount of structures is involved, it is preferable to adopt an approach that permits a rapid check of some significant vulnerability parameters, both for sites and structures. In this paper, an ambient tremor measurement approach (PICOS-Vul method) is illustrated and it is shown how the method can be used for a direct and rapid characterization of some vulnerability parameters that represent the dynamical behaviour of each structure. [ABSTRACT FROM AUTHOR]

The current practice of detailed seismic risk assessment cannot be easily applied to all the bridges in a large transportation networks due to limited resources. This paper presents a new approach for seismic risk assessment of large bridge inventories in a city or national bridge network based on the framework of probabilistic performance based seismic risk assessment. To account for the influences of local site effects, a procedure to generate site-specific hazard curves that includes seismic hazard microzonation information has been developed for seismic risk assessment of bridge inventories. Simulated ground motions compatible with the site specific seismic hazard are used as input excitations in nonlinear time history analysis of representative bridges for calibration. A normalizing procedure to obtain generalized fragility relationships in terms of structural characteristic parameters of bridge span and size and longitudinal and transverse reinforcement ratios is presented. The seismic risk of bridges in a large inventory can then be easily evaluated using the normalized fragility relationships without the requirement of carrying out detailed nonlinear time history analysis. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents an integrated and extensible framework for assessment of the impact of earthquakes on civil infrastructure systems, particularly buildings and bridges. The framework, referred to as NEES Integrated Seismic Risk Assessment Framework (NISRAF), is developed with a focus on improving the reliability of earthquake assessment results. The components are structural fragility assessment using measured data and hybrid simulation, hazard characterization by free-field site response analysis, and integrated impact assessment. The hazard and fragility components are refined by employing nonlinear site response tools and model updating techniques, respectively. Several of these NISRAF components are tailored to achieve seamless integration and to arrive at an operational system. The novelty of the developed framework is primarily the integration of the various components of earthquake impact assessment, which have not been deployed in such an application before. The framework has been built and demonstrated via applications to a test bed in California. Earthquake impact assessment results using the generated hazard map and fragility curves correlate well with field reports, indicating the efficacy of the approach. [Copyright &y& Elsevier]

Abstract: Performance-based earthquake engineering (PBEE) assessment studies on highway bridges can only address post-earthquake repair fully when considering the response of the bridge-foundation-ground and the consequences of damage and repair to all system components. In this paper, nonlinear time history analysis of coupled bridge-foundation-ground systems is coupled with a PBEE framework to investigate a typical highway overpass bridge founded on different soil profiles. The prototype bridges are typical reinforced concrete highway overpass bridges with single-column bents founded on four sites of varying stiffness and strength profiles ranging from rigid rock to weak upper soil strata. Probabilistic repair cost and time response quantities are used to contrast performance of the four scenarios. Intensity-dependent repairs, repair hazard curves, and repairs disaggregated by performance groups indicate contributions to system repair for each scenario. A sensitivity study is presented that demonstrates the most important parameters to be the damage state and repair quantities related to the foundations and abutments. [Copyright &y& Elsevier]

The article discusses a study which examined the seismic response of isolated structures on bearings with bilinear and trilinear behavior. It cites the application of a dimensional analysis to understand the significance of parameters controlling the isolation systems' mechanical behavior. Results of the study showed that the presence of intermediate slope is not significant to the peak response of isolated structures. Findings also revealed a difference between coefficients of friction in sliding surfaces and the ratio of the intermediate to the final slope. It notes that configurations can be computed through the replacement of double concave spherical bearings with single concave spherical with effective radius of curvature and coefficient of friction.

The aim of this paper is to determine the earthquake behavior of the Kömürhan Highway Bridge, located at the 51st kilometre of the Elazığ-Malatya highway over the Fırat River, after finite element model updating using operational modal analyses. Finite element models of the bridge are built with the SAP2000 program to obtain analytical dynamic characteristics such as natural frequencies and mode shapes. The ambient vibration tests are performed using operational modal analysis under traffic loads to attain experimental dynamic characteristics. Vibration data is gathered from both the box girder and bridge deck to compare the results. Measurement time, frequency span, and effective mode number are determined following similar studies and literature. The peak picking method in the frequency domain is used for output-only modal identification. The finite element model of the bridge is updated by changing some uncertainties in the parameters such as material properties and boundary conditions to eliminate the differences between analytical and experimental dynamic characteristics. An analytical model of the bridge after finite element model updating is analyzed using the 1992 Erzincan, Turkey earthquake record, which occurred near the region, to determine the earthquake behavior of the bridge. At the end of the study, the maximum differences in the natural frequencies are reduced on average from 10% to 2%, and a good agreement is found between analytical and experimental natural frequencies and mode shapes by model updating. Also, the variation of internal forces such as bending moment, axial forces, and shear forces for the bridge deck and columns are presented in detail. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the influence of wave velocity and the dispersion of waves associated with variations in seismic ground motions, on the inelastic responses of four 344 m long bridges. The bridges were 9 span continuous prestressed concrete box girders supported on sliding bearings, which eventually permitted movement in the longitudinal direction of the bridges, with shear keys that prevented transverse movement. The sub-structure consisted of reinforced concrete circular piers with cross-heads and rigid beams at the abutments. Earthquake motions were applied in the transverse direction for two bridges and for two others, with two expansion joints, the motions were applied longitudinally. The analyses of the latter were carried out to examine expansion gap movements and all analyses were carried out to produce time-history responses of pier drift, pier shear forces and pier curvature demands. The reinforcement in the piers was modelled so that either one base hinge can form or one base hinge with a hinge at the top of the pier. Pier heights varied between 5 m and 11 m or, for one bridge, were of constant height of 11 m. The non-uniform earthquake inputs at supports were generated by using the conditional simulation method with a natural earthquake record specified at one abutment. The response to wave velocities from 100 to 2000 m/s and infinity were studied both without dispersion and with various degrees of dispersion. The El Centro 1940 N–S and Sylmar Northridge 1994 N–S were used as the transverse earthquakes and the E–W components were used longitudinally. The results of these analyses show that non-uniform earthquake ground motions significantly influence the response of long bridges both with and without expansion joints. The responses change significantly with travelling wave velocity and the degree of dispersion and these can be more critical than for uniform inputs. Significant dispersion can generate rotational inertia of the deck and, with the torsional stiffness of the deck, can lead to the formation of top and bottom pier hinges and significantly larger shear forces compared to the normal cantilever design of these types of bridge piers. [Copyright &y& Elsevier]

Rooted in structural dynamics theory, two approximate procedures for estimating peak responses of linearly elastic “ordinary” bridges crossing fault-rupture zones are presented: response spectrum analysis (RSA) procedure and a linear static analysis procedure. These procedures estimate the peak response by superposing peak values of quasi-static and dynamic responses. The peak quasi-static response in both procedures is computed by static analysis of the bridge with peak values of all support displacements applied simultaneously. In RSA, the peak dynamic response is estimated by dynamic analysis including all significant modes, which is simplified in the latter procedure to static analysis of the bridge for appropriately selected forces; usually only one mode—the most dominant mode—is sufficient in the RSA procedure. Appearing in these procedures is the “effective” influence vector that differs from the influence vector for spatially uniform excitation, and the response spectrum used in the RSA procedure differs from the standard California Department of Transportation (CALTRANS) spectrum. Both of these simplified procedures provide estimates of peak response that are close enough to results of the “exact” response history analysis to be useful for practical application. [ABSTRACT FROM AUTHOR]

Bridge columns are subjected to combined actions of axial force, shear force and bending moment during earthquakes, caused by spatially-complex earthquake motions, features of structural configurations and the interaction between input and response characteristics. Combined actions can have significant effects on the force and deformation capacity of RC columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. This paper evaluates the seismic response of three prototype reinforced concrete bridges using comprehensive numerical models that are capable of simulating the complex soil-structural interaction effects and nonlinear behavior of columns. An analytical approach that can capture the shear-flexural interacting behavior is developed to model the realistic nonlinear behavior of RC columns, including the pinching behavior, strength deterioration and stiffness softening due to combined actions of shear force, axial force and bending moment. Seismic response analyses were conducted on the prototype bridges under suites of ground motions. Response quantities of bridges (e.g., drift, acceleration, section force and section moment etc.) are compared and evaluated to identify the effects of vertical motion, structural characteristics and the shear-flexural interaction on seismic demand of bridges. [ABSTRACT FROM AUTHOR]

An analytical study investigating how changes in the mechanical properties of individual seismic isolators affect the response of isolated bridge structures subjected to earthquake excitation is summarized. Nonlinear response-history analyses are conducted utilizing bins of recorded earthquake ground motion pairs. Twenty bilinear isolation systems are considered so that the results of this study are broadly applicable to the design of seismic isolation systems in the United States. Variations in the mechanical properties are considered using a property modification factor, λ, to modify the appropriate bilinear isolator parameter. The results of analyses considering nominal and modified isolation systems are used to systematically identify changes in system response as a function of the property modification factor. These results are used to determine threshold values of the property modification factor that should aid engineers in the preliminary design and assessment of an isolation system prior to performing the bounding analysis now required by bridge and building design codes. [ABSTRACT FROM AUTHOR]

To investigate the seismic behavior of bridge pile-to-pile-cap connections, five full-scale H-shaped steel pile-to-pile-cap connection subassemblies representing a portion of a typical bridge pile foundation were tested. Two of the full-scale subassembly specimens were subjected to a vertical cyclic load simulating axial forces in a pile caused by footing overturning during an earthquake attack. Two others were loaded with cyclic lateral force and constant vertical load. One specimen was tested under proportionally varied vertical and horizontal forces. It was found that, although it was designed as a pinned connection following the current design standard, the pile-to-pile-cap connection can sustain a significant amount of moment. Localized brittle failure was observed in the vicinity of the pile-to-pile-cap connection, as the results of unexpected moment resistance. Test results also showed that the anchorage details using two V-shape bars could not develop the full-design ultimate tensile capacity. Analytical methods are developed and found adequate to evaluate the strength of the pile-to-pile-cap connection. [ABSTRACT FROM AUTHOR]

The methodology for dealing with spatial variability of ground motion, site effects and soil–structure interaction phenomena in the context of inelastic dynamic analysis of bridge structures, and the associated analytical tools established and validated in a companion paper are used herein for a detailed parametric analysis, aiming to evaluate the importance of the above effects in seismic design. For a total of 20 bridge structures differing in terms of structural type (fundamental period, symmetry, regularity, abutment conditions, pier-to-deck connections), dimensions (span and overall length), and ground motion characteristics (earthquake frequency content and direction of excitation), the dynamic response corresponding to nine levels of increasing analysis complexity was calculated and compared with the ‘standard’ case of a fixed base, uniformly excited, elastic structure for which site effects were totally ignored. It is concluded that the dynamic response of RC bridges is indeed strongly affected by the coupling of the above phenomena that may adversely affect displacements and/or action effects under certain circumstances. Evidence is also presented that some bridge types are relatively more sensitive to the above phenomena, hence a more refined analysis approach should be considered in their case. Copyright @ 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

With the recent advent of performance‐based earthquake engineering (PBEE) in seismic design practice of buildings serving as an impetus for this work, initial steps toward a fully probabilistic performance‐based seismic design (PBSD) method for bridges, a less trodden area in terms of PBEE applications, are taken herein by assembling an updated probabilistic seismic performance assessment framework for ordinary standard bridges (OSBs) in California. The framework stems from the comprehensive PBEE methodology developed under the auspices of the Pacific Earthquake Engineering Research (PEER) Center. With performance measures defined as the risk associated with the exceedance of a set of damage/limit‐states (LSs), improvements from the state‐of‐the‐art literature on the PEER PBEE methodology are incorporated, including (1) introduction of an improved intensity measure ‐ average spectral acceleration over a period range, (2) conditional mean spectrum‐based hazard‐consistent and site‐specific ground motion selection, (3) introduction of material strain‐based engineering demand parameters, (4) use of practical LSs pertinent to seismic damage evaluation of bridges, and (5) development of strain‐based normalized fragility functions for the considered LSs. The updated framework, assembled herein using a specific testbed California OSB as a case in point, is general within its scope and is applicable to the gamut of design situations representative of the population of OSBs in California. With the PEER PBEE framework implemented for OSBs in an updated and rigorous form, the groundwork for utilizing this framework in the context of PBSD of such bridges is laid. [ABSTRACT FROM AUTHOR]

The investigation reported in the paper is an attempt to assess the relevance of soil-structure interaction (SSI) effects on the dynamic response of bridge piers responding in the inelastic range and, in particular, on the maximum required ductilities in the critical regions of the superstructure. The problem is dealt with reference to a simple structural configuration: a vertical cantilever carrying a mass at the top, representing realistic cases of bridge piers of common geometry with spread footing foundations. A relatively large number of parameters has been considered in the analysis, with a total of 240 cases examined, and with ductility demands on the piers ranging between 1.5 and 7. The results indicate that although in most cases SSI produces an increase of the maximum displacements, this effect is not very significant, and the inelastic demand in terms of curvature essentially remains unaffected by soil-structure interaction, showing a tendency to decrease. Finally, the stability of these conclusions against rather extreme variations of the parameters is confirmed by the results of additional bounding analyses, characterized by unusually soft soil conditions and by a seismic excitation multiplied by a factor of two. [ABSTRACT FROM AUTHOR]

Simplified seismic assessment procedures relying on displacement‐based formulations have recently been implemented for the evaluation of the seismic performance in buildings and bridges. For bridges, displacement‐based assessment procedures have been formulated to predict the displacement response at several performance levels defined based on the expected damage on the structural elements. These displacement profiles have been subsequently used to estimate the performance level achieved under a given seismic hazard intensity and to develop damage fragility curves. For buildings, these concepts have been extended to compute economic losses in agreement with current performance‐based earthquake engineering procedures. In this study, existing displacement‐based formulations for the approximate seismic assessment of single‐column multi‐span continuous RC bridges, with non‐sacrificial shear keys for the pier‐to‐deck connections, are extended for the computation of expected annual losses under transverse direction excitation. Additionally, an iterative response spectrum analysis procedure, which directly considers higher mode effects, is proposed for computing the displacement response, and these results are also used to estimate direct expected annual losses. Results show that both procedures tend to compute higher losses when compared with those obtained with a fully probabilistic loss assessment framework, using demand estimations computed with nonlinear response history analysis. Results also show that the simplified loss assessment procedure is highly sensitive to the definition of the collapse fragility curve. [ABSTRACT FROM AUTHOR]

Long bridges and other lifeline systems are particularly susceptible to the spatial variability of earthquake actions. Even though it is a matter that has been substantially studied in the past decades, there are still plenty of issues with the engineering application of earthquake spatial variability. One of the difficulties is generating displacement time-histories with zero initial and small residual displacement values. This is essential to obtain results that have good quality in terms of the pseudo-static effects. Another difficulty is the uncertainty associated with the simulation of the spatial variability of the seismic ground motions in engineering applications (Zerva et al. in: 16th European conference on earthquake engineering, Thessaloniki, 2018). In this study, the conditional method for simulation of spatially variable ground motions is used and the respective displacement time-histories are generated. These time-histories are then applied to perform seismic analysis of a set of long irregular RC bridges, with different irregularity layouts and different total lengths. The goal of this study is to ascertain the impact of spatial variability on the seismic behaviour of these structures, according to their length, irregularity and to the coherency model of the strong motions and comparing the results with the case without spatial variability. The relative importance between dynamic and pseudo-static effects is also ascertained for each case-study. Finally, the definition of the cases for whom the effects of the spatially variable seismic ground motions are more detrimental than those of the uniform ground motions. [ABSTRACT FROM AUTHOR]

• Damage models for circular section RC cantilever columns are developed. • Three different Engineering Demand Parameters are considered. • Simplified relationships for implementation in large scale assessment are proposed. • Damage models for the limit state of shear failure are also generated. • Critical discussion on the applicability of proposed damage models is presented. Damage models are fundamental elements within probabilistic frameworks, such as Performance-Based Earthquake Engineering (PBEE), for the seismic assessment of RC structures. For bridges, in specific, there are not many available experimental results for the characterization of damage in the RC columns hence the numerical counterpart acquires particular relevance. In this paper, via Monte Carlo simulation and comparison with complementary experimental results, a damage model consisting of a library of median and logarithmic dispersion values for curvature ductility, displacement ductility and drift, describing the probability of reaching a particular damage limit state are generated as a function of key parameters of circular RC bridge columns. Four damage limit states are considered: slight, moderate, extensive and complete. Simplified relationships based on the full datasets are proposed for easier implementation. The proposed damage models can be used for threshold identification and economic loss assessment in performance-based earthquake engineering of RC bridges. [ABSTRACT FROM AUTHOR]

Summary: Rocking column‐foundation system is a new design concept for bridges that can reduce overall seismic damage, minimize construction and repair time, and achieve lower cost in general. However, such system involves complex dynamic responses due to impacts and highly nonlinear rocking behavior. This study presents a dimensionless regression analysis to estimate the rocking and shaking responses of the flexible column‐foundation system under near‐fault ground motions. First, the transient drift and rocking responses of the system are solved numerically using previously established analytical models. Subsequently, the peak column drifts and uplift angles are derived as functions of ground motion characteristics and the geometric and dynamic parameters of column‐foundation system in regressed dimensionless forms. The proposed response models are further examined by validating against the numerical simulations for several as‐built bridge cases. It is shown that the proposed model not only physically quantifies the influences of prominent parameters, but also consistently reflects the complex dynamics of the system. The seismic demands of rocking column‐foundation system can be realistically predicted directly from structural and ground motion characteristics. This can significantly benefit the design of bridges incorporating this new design concept. [ABSTRACT FROM AUTHOR]

Nonlinear static procedures (NSPs) are gaining wider use in performance based earthquake engineering practice due to their simplicity compared to rigorous nonlinear time history analysis (NTHA), and being implemented in the new generation of seismic design codes. In this study, a recently proposed Nonlinear Static Procedure (NSP) for the seismic performance assessment of building structures using the concept of generalized force vectors (GFV), is further validated through application to reinforced concrete bridges. This method, named generalized pushover analysis (GPA), maximizes the response of a chosen parameter during the seismic response, through the use of the GFV, which are a combination of modal forces representing the instantaneous force acting on the system when such parameter reaches its maximum. In this study, the original GPA implemented in buildings is adapted to bridge structures and four versions of the algorithm are tested. Two straight bridges, featuring different levels of vertical irregularity, are used as case study to validate the procedure, and the accuracy of the GPA algorithm is assessed by comparing the nonlinear static results with the 'exact' prediction from NTHA. Several levels of seismic hazard, represented in the expected return period of the target spectra, are considered to test the accuracy of the method for low and high seismic demand. Furthermore, the GPA results are also compared with a commonly employed NSP, the capacity spectrum method. The results obtained for the case study suggest that GPA algorithm for bridges is suitable as a NSP approach for the seismic assessment of bridge structures, demonstrating a good fit with NTHA results and superiority with respect to the predictions of the selected traditional NSP. [ABSTRACT FROM AUTHOR]