Ground Motions Representative Research Articles

A Seismic Site Factor Adjustment Framework for Sloping Grounds and Its Application to Charleston, South Carolina

ABSTRACT Ground motions and seismic site factors for the design and analysis of infrastructure systems are typically computed based on one-dimensional (1-D) site response analysis, assuming the ground surface is horizontal and the earthquake waves propagate vertically near the ground surface. The 1-D results may not be applicable for sloping ground surfaces and layer interfaces, and therefore, the 1-D results must be adjusted for sloping grounds. In this study, a general framework for developing seismic site factors for sloping grounds and its application for Charleston, SC is presented. The two-dimensional (2-D) site response analysis results of sloping ground were compared with the 1-D horizontal ground results to develop slope adjustment factors. A total of 385 2-D nonlinear finite element simulations of sloping grounds were performed considering seven ground inclinations, 11 shear wave velocity profiles, and five ground motions representative of the area. The results show that the surface responses computed from sloping ground analyses significantly differ from those of horizontal ground analyses. By comparing the 1-D and 2-D results, a set of slope adjustment factors was developed and expressed as an easy-to-use chart. The slope adjustment factor at a project site can be obtained from the proposed chart using site-specific VS30 and ground inclination at a selected period.

Full-scale shaking table tests of cross-laminated timber structures adopting dissipative angle brackets and hold-downs with soft-steel and rubber

Cross-laminated timber (CLT) has recently attracted significant interest in building timber or hybrid structures owing to the rapidly growing demand for low-carbon construction materials with excellent mechanical properties. To investigate the seismic performance of CLT structures adopting novel dissipative angle brackets and hold-downs with soft-steel and rubber (i.e., SRD-ABs and SRD-HDs), a series of shaking table tests were performed on two full-scale specimens, i.e., a benchmark specimen (Specimen Ⅰ) and a specimen with a multi-doorway at the ground (Specimen Ⅱ). Several representative ground motions, including the Turkey wave, El Centro wave, Wenchuan wave, and Shanghai artificial wave, were selected as excitations, whose peak acceleration increased gradually from 0.035 g to 0.80 g. The damage patterns of the structures were revealed, and the dynamic characteristics and responses were obtained and analyzed. The results show that the fundamental frequencies of Specimen Ⅰ and Specimen Ⅱ were 4.125 Hz and 3.625 Hz, respectively. The mode shapes of each specimen remained similar before tests with peak ground acceleration (PGA) of 0.51 g, with only a slight decrease of approximately 5 % in the fundamental frequency, indicating that the specimens only suffered minor damage because of the great energy-dissipating capacity of the SRD-ABs and SRD-HDs. After experiencing tests with PGA of 0.80 g, the specimen exhibited a maximum inter-story drift of 1/60 with a structural damping ratio of 13 %, and the damage was mainly exhibited at the SRD-ABs and SRD-HDs, which realized the performance objective of replaceability of dissipative connections and repairability of structures under the 9-degree rare earthquakes. Furthermore, non-linear numerical models were developed to duplicate the dynamic characteristics and responses of the test specimen, and the analytical results from the models show satisfactory agreement with the test results. Overall, the outcomes of this paper can provide valuable references for future research and applications of CLT structures with the SRD-ABs and SRD-HDs.

Seismic response of a ground-bridge structure system in horizontal and inclined liquefiable site to near-fault pulse-like ground motions

Previous earthquake events have indicated that bridge structures are more vulnerable to severe damage when subjected to near-fault pulse-like (NF-P) ground motions. Structural seismic damage will be exacerbated when bridges are located in liquefiable site. Meanwhile, the seismic response of bridges located in inclined liquefiable site is different from that of bridges in horizontal liquefiable site. This study focuses on exploring the seismic response of a ground-bridge structure system located in horizontal and inclined liquefiable site to the NF-P ground motions. The seismic response of the whole system to the near-fault non-pulse-like (NF-NP) and far-field (FF) ground motions is studied for comparison. Two three-dimensional (3D) finite element (FE) models of the ground-structure system considering soil-pile interaction are developed. They are associated with the horizontal and inclined liquefiable site, respectively. The seismic responses of the ground-bridge structure system to the three different types of ground motions (i.e., NF-P, NF-NP and FF) are comprehensively evaluated from two perspectives. On the one hand, the seismic time history responses of the ground-bridge structure system under single representative ground motion are comprehensively assessed. On the other hand, the average responses of the ground-bridge structure system under multiple types of ground motions are explored. The results reveal that in contrast to the NF-NP and FF ground motions, the NF-P ground motions have more significant effect on various responses of the ground-bridge structure system. In addition, compared to the bridge in horizontal liquefiable site, the bridge in inclined liquefiable site exhibits larger seismic responses. Therefore, the velocity pulse effect of the NF-P ground motions and the liquefaction effect of the inclined site need to be emphasized in structural seismic design.

Updated Predictive Models for Permanent Seismic Displacement of Slopes for Greece and Their Effect on Probabilistic Landslide Hazard Assessment

Earthquake-triggered landslides have been widely recognized as a catastrophic hazard in mountainous regions. They may lead to direct consequences, such as property losses and casualties, as well as indirect consequences, such as disruption of the operation of lifeline infrastructures and delays in emergency response actions after earthquakes. Regional landslide hazard assessment is a useful tool to identify areas that are vulnerable to earthquake-induced slope instabilities and design prioritization schemes towards more detailed site-specific slope stability analyses. A widely used method to assess the seismic performance of slopes is by calculating the permanent downslope sliding displacement that is expected during ground shaking. Nathan M. Newmark was the first to propose a method to estimate the permanent displacement of a rigid body sliding on an inclined plane in 1965. The expected permanent displacement for a slope using the sliding block method is implemented by either selecting a suite of representative earthquake ground motions and computing the mean and standard deviation of the displacement or by using analytical equations that correlate the permanent displacement with ground motion intensity measures, the slope’s yield acceleration and seismological characteristics. Increased interest has been observed in the development of such empirical models using strong motion databases over the last decades. It has been almost a decade since the development of the latest empirical model for the prediction of permanent ground displacement for Greece. Since then, a significant amount of strong motion data have been collected. In the present study, several nonlinear regression-based empirical models are developed for the prediction of the permanent seismic displacements of slopes, including various ground motion intensity measures. Moreover, single-hidden layer Artificial Neural Network (ANN) models are developed to demonstrate their capability of simplifying the construction of empirical models. Finally, implementation of the produced modes based on Probabilistic Landslide Hazard Assessment is undertaken, and their effect on the resulting hazard curves is demonstrated and discussed.

Nonlinear Dynamic Analysis of Pilotis Structures Supported by Drift-Hardening Concrete Columns.

Pilotis structures consisting of upper concrete bearing-walls and a soft first story have been well used in residential and office buildings in urban areas to primarily accommodate parking lots. In this research, drift-hardening concrete (DHC) columns developed by the authors are proposed to form the pilotis story with the aims of reducing its excessive residual drift caused by stronger earthquakes than anticipated in current seismic codes, mitigating damage degree, and enhancing resilience of the pilotis story. Nonlinear dynamic analysis was conducted to investigate the dynamic response characteristics of the wall structures supported by DHC columns. To this end, two sample six-story one-bay pilotis structures were designed following the current Japanese seismic design codes and analyzed. One sample structure is supported by ductile concrete (DC) columns, while the other is supported by DHC columns, which have the same dimensions, steel amount, and concrete strength as DC columns. Three representative ground motions were adopted for the nonlinear dynamic analysis. The analytical parameter was the amplitude of peak ground acceleration (PGA), scaled by the peak ground velocity (PGV) ranging between 12.5 cm/s and 100 cm/s with an interval of 12.5 cm/s. The analytical results have revealed that the residual drift of the pilotis story composed of DHC columns could be reduced to nearly zero under selected earthquakes scaled up to PGV = 100 cm/s, owing to not only the inherent self-centering ability of DHC columns but also the shake-down effect, which implies that the use of DHC columns can greatly enhance resilience of pilotis structures under strong earthquake inputs and promote its application in the buildings located in strong earthquake-prone regions. The maximum inter-story shear forces (MISFs) along the building height of the two models are also compared.

Numerical seismic analysis of high-piled wharf strengthened with CFRP

High-piled wharves are widely employed in coastal areas, but their vulnerability to earthquake damage necessitates effective strengthening measures. This research focuses on investigating the effectiveness of carbon fiber reinforced polymer (CFRP) laminates in enhancing the seismic resistance of high-piled wharves. Full-scale 3D numerical high-piled wharves, divided into As-built groups and Retrofit groups, were established herein. During modeling, the concrete damage plasticity model (CDP) and the finite-infinite coupling element were contemplated. Two representative ground motions, i.e., the EI Centro wave and the Northridge wave, with peak accelerations of 0.2g and 0.4g, respectively, were utilized to simulate different earthquake scenarios. The responses of the resulting earthquake-induced deck displacement, pile distortion, and pile bending moment profile were explored. The computational analysis revealed significant improvements in the seismic performance of the retrofitted wharves compared to the as-built structures, proving that the externally bonded CFRP method was of great significance in improving overall structural seismic performance. Notably, the retrofitted wharf exhibited reduced deck displacement and remarkable decreases in pile deformation and bending moment. The modeling and analysis techniques can be applied to general wharves or other buildings strengthened with CFRP.

Ranking method of the severest input ground motion for underground structures based on composite ground motion intensity measures

Underground structure seismic response analyses and structural safety seismic designs are based on the scientific and reasonable selection of ground motion records. Different input ground motions lead to varies seismic response due to the strong randomness of ground motion. The severest input ground motion for the seismic analysis of underground structures cannot be obtained via a single intensity measure (IM). For this purpose, a ranking method is proposed based on composite IM for the severest input ground motion for underground structures. Four composite ground motion IMs constructed using the partial least squares regression (PLSR) method are proposed as representative ground motion IMs of the seismic failure potential of underground structures. These composite ground motion IMs correspond to the evaluation of four engineering demand parameters (EDPs), including the moment, shear force, axial force, and relative displacement of the central column of a subway station. Elastic-plastic time-history analyses of a two-story three-span subway station are performed given 64 ground motion records to provide the necessary data samples. After the construction, a bilinear logarithmic regression analysis is carried out. The results show that the proposed composite ground motion IMs have a higher correlation with the seismic dynamic responses than single IMs with respect to effectiveness, practicability, and proficiency. Finally, a ranking method for the severest input ground motion based on these composite ground motion intensity parameters is proposed. This method can be used to obtain the severest design ground motion of underground structures for seismic design.

Dynamic Modal Analyses of Building Structures Employing Site-Specific Response Spectra Versus Code Response Spectrum Models

This paper is aimed at giving structural designers guidance on how to make use of elastic site-specific response spectra for the dynamic modal analysis of a structure in support of its structural design. The use of response spectra in support of the pushover analysis of an RC building forming part of the non-linear static analysis procedure (that can be used to predict seismic demand without relying on the code-stipulated default R factor) is also presented. Seismic analysis of structures based on the use of site-specific response spectra can help to achieve a more optimised, and cost-effective, structural design compared to the conventional approach employing a response spectrum model stipulated by the code for different site classes. Currently, the methodology is only adopted in major projects in which enough resources are available to engage experts who are skilled in operating the procedure; thus, the use of site-specific response spectra in structural engineering practice is still limited despite the merits of the procedure. Deriving a site-specific response spectrum requires a database of representative ground motion records to be developed. Extra analytical tasks to be undertaken include the processing of bore log data, site response analyses, and selection/scaling of bedrock accelerograms for input into site response analyses. Guidelines for implementing this design methodology are currently lacking. To promote the wide adoption of site-specific seismic design, this article presents the procedure for developing the required site-specific design spectra, as well as guidelines for applying these spectra for seismic design based on analyses of linear, or nonlinear, models of the building. Non-linear analysis can be accomplished by dealing with macroscopic models as illustrated in a case study.

SVD enabled data augmentation for machine learning based surrogate modeling of non-linear structures

The computationally expensive estimation of engineering demand parameters (EDPs) via finite element (FE) models, while considering earthquake and material parameter uncertainty limits the use of the Performance Based Earthquake Engineering framework. Attempts have been made to substitute FE models with surrogate models, however, most of these models are a function of building parameters only. This necessitates re-training for earthquakes not previously seen by the surrogate. In this paper, the authors propose a machine learning based surrogate model framework, which considers both these uncertainties in order to predict for unseen earthquakes. Accordingly, earthquakes are characterized by their projections on an orthonormal basis, computed using SVD of a representative ground motion suite. This enables one to generate varieties of earthquakes by randomly sampling these weights and multiplying them with the basis, resulting in a large data set that is needed to train machine learning models. The weights along with the constitutive parameters serve as inputs to a machine learning model with EDPs as the desired output. Four competing machine learning models were tested and it was observed that a deep neural network (DNN) gave the most accurate prediction. The framework is validated by using it to successfully predict the peak response of one-story and three-story shear frame buildings represented using nonlinear spring–mass–damper systems, subjected to unseen far-field ground motions.

Numerical modelling of the seismic response of gentle slopes in Southeastern Brazil

The offshore Campos Basin, located in Southeastern Brazil represents an important area in the Brazilian economy as it is one of the most prolific oil-producing basins in the country. With the development of offshore infrastructures in this region, structural design and location must consider different geohazards. This paper addresses the seismic response of gentle submarine slopes subjected to small-to-moderate-sized earthquakes, representative of the Brazilian seismic conditions. The seismic analyses employed numerical modeling, with a nonlinear constitutive model. A set of bedrock ground motions representative of the offshore Campos Basin seismicity was obtained, employing a Uniform Hazard Response spectrum for the region and earthquakes from the Pacific Earthquake Engineering Research (PEER) database. Numerical modelling results showed that, even for small slope angles and moderate earthquakes, there is an accumulation of permanent displacements and shear strains in the downslope direction can affect the stability and performance of existing offshore infrastructures. The findings of this research provide a valuable reference for the prediction of seismic displacements, shear strains and seabed amplification or attenuation of earthquakes on gentle slopes in deep-water deposits similar to those found in the offshore Campos Basin.

Offshore ground motion characteristics on the horizontal PGA, spectral acceleration, frequency content and significant duration from the 2021 Mw 7.1 and 2022 Mw 7.4 offshore earthquakes near the Japan Trench area

The two large offshore earthquakes that occurred in Japan's eastern Fukushima region on February 13, 2021, Mw 7.1 and March 17, 2022, Mw 7.4 are the two largest offshore earthquakes recorded by the large-scale permanent ocean-bottom seismograph network (S-net). The two earthquakes are both subduction slab earthquakes and caused great damage to onshore structures. The offshore ground motions from the S-net within a fault distance of 300 km were selected to investigate the characteristics of the strong offshore motions. The onshore ground motions are also selected from the K-net to compare the differences in offshore and onshore ground motions. These onshore and offshore datasets were used to calculate the representative ground motion parameters: the peak ground acceleration (PGA), spectral acceleration, frequency content and significant duration of the earthquakes. Here we present the comparison of the offshore and onshore ground motions in amplitude, duration and frequency content, as well as the applicability of the representative onshore ground motion model (GMM) to the offshore region. Additionally, we provide the spatial contours of the parameters used in this study and the residual analysis to examine the effects of the water depth, sedimentary layer and station deployment method on the offshore ground motions. We found that the PGA and spectral accelerations of unburied seafloor stations are larger than those of buried stations, and the attenuation rate observed from the spatial contours between the offshore and onshore regions is different, which shows the necessity of proposing a new prediction model for the PGA and spectral accelerations in offshore regions. The significant duration of offshore ground motions is consistent with the onshore prediction model of significant duration in the subduction zone but is on average greater than those of onshore ground motions. For the frequency content, there is no prediction model for subduction zones at present. The frequency-content parameters of offshore ground motions are relatively consistent with the frequency-content model for greater depths. On the whole, the complex environment at the ocean bottom has the most significant influence on the spectral accelerations over long periods and has some influence on the duration and frequency content, but the overall difference is smaller than the PGA and spectral accelerations.

Loading protocols for seismic qualification of steel plate shear walls

As a new type of lateral force resisting member, steel plate shear walls (SPSWs) have the advantages of excellent energy dissipation, high lateral stiffness, and ductility. Owing to the lack of loading characteristics of an actual earthquake in the existing loading protocol of SPSWs, the interpretation of the seismic performance of SPSWs is still challenging. A set of standardized loading protocols for SPSWs under far-field and near-fault earthquakes were proposed, to replicate the real loading histories in severe earthquakes. By using the rainflow counting method, the seismic parameters (such as damage cycle, interstory drift range, and residual interstory drift) from four frame–SPSW structures subjected to a series of representative ground motions, were analyzed to develop the loading protocols. Moreover, the rationality of the proposed loading protocols was discussed and verified by demonstrating the cumulative distribution function and energy dissipation of these protocols. It is well illustrated that the proposed protocols can truly simulate the loading history of members and accurately reflect the seismic damage demands in the inelastic stage.

Discussion of Post-earthquake fast damage assessment using residual displacement and seismic energy: Application to Mexico City

A discussion on the article by Quinde et al. is presented. The methodology introduced by the authors is based on residual displacements computed from the inelastic response of elastoplastic single-degree-of-freedom systems subjected to synthetic ground motions representative of those recorded at soft soil sites in Mexico City. While the subject to the article is pertinent for post-earthquake assessment, this discussion points out and clarifies several issues about residual displacement demands and their estimation based on previously published investigations by the discussers.

Seismic evaluation of industrial steel moment resisting frames with shape memory alloys using performance-spectra-based method

Seismic evaluation of industrial facilities may need to employ multi-performance indicators in various yielding stages towards a more delicate design methodology. This paper develops a performance-spectra-based method to evaluate the seismic performance of industrial steel moment resisting frames (MRFs) with shape memory alloys (SMAs) considering multi-performance indicators and hysteresis transition. The work commences with demonstration of the hysteresis transition of a steel MRF with SMAs from the ‘self-centring stage’ to the ‘post self-centring stage’. Then, based on the single-degree-of-freedom (SDOF) analogy and the hysteretic model considering hysteresis transition, a performance-spectra-based space for quantifying the seismic behaviour of an industrial steel MRF with SMAs including multi-performance indicators is established. In this study, the performance-spectra-based space employs three essential indicators (i.e. energy modification factor, peak acceleration ratio and residual displacement ratio). To demonstrate the application and validate the adequacy of the proposed method for seismic evaluation of industrial steel MRFs with SMAs, two prototype steel MRFs equipped with SMA connections for industrial use are designed and assessed under representative earthquake ground motion ensembles. By comparing essential structural seismic response quantities (i.e. maximum roof displacement, peak interstorey drift ratio, peak floor acceleration and interstorey residual drift ratio) predicted by the proposed method with those calculated by nonlinear-response-history analyses (NL-RHAs), the effectiveness of the proposition is confirmed.

A Simple Critical Response Evaluation Method for Base-Isolation Building-Connection Hybrid System Under Double Impulse as Representative of Near-Fault Ground Motion

We revisit a unique building system including a base-isolation, building-connection hybrid control system. The base-isolation system withstands pulse-type earthquake ground motions effectively and the building-connection system resists long-duration earthquake ground motions efficiently. A simple smart critical response evaluation method without nonlinear time-history response analysis is proposed for this hybrid building system under near-fault ground motions. An analytical expression of the maximum elastic-plastic deformation of a damped bilinear hysteretic single-degree-of-freedom (SDOF) model under critical double impulse as a representative of pulse-type ground motions derived in our previous paper plays an important role in the development of the simple critical response evaluation method. A two-step transformation procedure into an SDOF model is proposed. The first step is the transformation of the main base-isolated building into an SDOF system and the second step is the reduction of the connecting dampers supported on a sub building to a damper with a sophisticated compensation factor on an assumed rigid wall. The evaluation of damping coefficients with the consideration of yielding of the base-isolation story is a key step in this paper. Different from the previous work, the equivalent damping coefficient is derived depending on the response range before and after yielding of the base-isolation story. This treatment enhances the accuracy of the proposed method. The accuracy and reliability of the proposed response evaluation method is demonstrated by the time-history response analysis of the multi-degree-of-freedom (MDOF) model.

Seismic Response of Two Site Models and Their Effects on the Railway Cable-Stayed Bridge

In order to accurately analyze the seismic response of the site and their effects on a railway cable-stayed bridge, the site condition of the railway cable-stayed bridge was surveyed, and geotechnical exploration holes ZK1 and ZK2 were set near the left and right tower of the bridge to gain the detailed geological data, then 32 representative ground motions records were selected corresponding to the site characteristics, and the equivalent linear and nonlinear model were established to analyze the site seismic response of 32 representative ground motions based on the Deepsoil Software. Next, to investigate the influence of site seismic response on the long-span railway cable-stayed bridge, the seismic response of the cable-stayed bridge considering site effect are calculated and evaluated via time history analysis under one-dimensional and multi-point excitation based on the ANSYS platform. At last, several critical and meaningful conclusions are drawn.

Aggravation factors for 2D site effects in sedimentary basins: The case of Norcia, central Italy

In this article the seismic site response of the Norcia basin, Central Italy, has been analyzed using both 1D and 2D ground response numerical models. Period-dependent aggravation factors (PDAFs) quantifying the difference between 2D and 1D site response are provided for two representative cross-sections of the basin. Time-domain linear visco-elastic and non-linear analyses were carried out by the finite difference commercial program FLAC2D. For the former, the PDAFs were computed using a suite of representative ground motion records. Although the basin sediments are constituted by rather stiff soils, the Norcia basin is found to produce a consistent modification and enhancement of ground motion. It is found that the most important source of ground motion aggravation was the generation of Rayleigh waves at the basin edges. The variability of the PDAFs was explored by considering the effects of frequency content of input motion, damping ratio, irregularity of the alluvial-bedrock interface. The effect of the non-linear response of the sediments on the PDAFs was also addressed with reference to the Mw 5 October 30, 2016 event.

Influence of Bearing Types and Design Code Advances on Seismic Vulnerability of Simply Supported Highway Bridges

ABSTRACT Multi-span simply supported (MSSS) highway bridges are one of the most common bridge types across the world and have several vulnerable components, including bearings, piers, and abutments. Although several past studies have evaluated the seismic response and fragility of common multi-span simply supported bridges, there is negligible research that explores the influence of bearing types, and non-ductile failure modes of bridge piers on the performance of older non-seismically designed simply supported bridges. Additionally, a better understanding of seismic risk to highway transportation systems necessitates the exploration of design code advances and subsequent impact on the seismic vulnerability of MSSS highway bridges. Consequently, this study also focuses on developing and comparing fragility curves for the older design era non-seismically designed, and modern era seismically designed MSSS bridges. High-fidelity three-dimensional (3-D) analytical models, which account for the nonlinear behavior of different components, including non-ductile failure modes of bridge piers, are developed. Deterministic seismic response assessment reveals a higher seismic demand on bridge pier for MSSS bridges with steel bearings as compared to those with elastomeric bearings. The bridge component and system fragility curves are developed with a suite of ground motions representative of the seismic hazard of the case-study region. Results reveal the significant vulnerability of older non-seismically designed MSSS bridge with steel bearings due to the non-ductile failure of the bridge pier. The vulnerability of the bridge is significantly reduced with the adoption of modern seismic design and detailing practices.

Selection of earthquake ground motion accelerograms for the continental margin of Southeastern Brazil

Brazil is in an intraplate area of low to moderate seismicity, this means that few or no records of strong ground motions are available. Part of the site response analysis and seismic design of structures require the use of acceleration time-histories compatible with a specified target response spectrum. This study aims to utilize methodologies based on the use of existing earthquake records from a well-known database and synthetic accelerograms to obtain ground motions representative of the Brazilian Southeast Region, particularly in the offshore Campos Basin. Information from a probabilistic seismic hazard assessment performed in the interest area was employed as input to the methodologies applied in terms of target response spectrum and the dominant earthquake scenarios. Besides, the acceleration time-histories of two relatively recent earthquakes that occurred in the Brazilian Southeast were used to apply one of the approaches to obtain a synthetic spectrum compatible accelerogram.

Seismic behaviour of multi-storey gravity-controlled rocking braced-frame buildings including floor vertical response

Gravity-controlled rocking braced frames (G-CBRFs) are cost-effective low-damage self-centring lateral force resisting systems that allow the reduction of the seismic force demands in structures subjected to earthquakes, while relying only on the gravity loads they carry to ensure self-centring. Due to column uplift, significant masses are mobilized, thus activating vertical fundamental modes of vibration that affect the overall seismic behaviour of the structures. This article presents an examination of the seismic response of G-CBRF structures, including the response of the roof and floor framing systems. Twenty-two buildings were designed for this study, with various combinations of building heights (2-, 4-, and 8-storeys), building locations (eastern and western Canada), site classes (soil C and E), and location of the braced frame within the building (interior or exterior column lines). For each design, two framing configurations were studied, with secondary beams parallel or perpendicular to the braced frames. Non-linear response history analyses were performed using representative ground motions selected and scaled according to the National Building Code of Canada requirements. Effects of the vertical component of the ground motions and energy dissipated through friction in beam-to-column connections were also of focus. Incremental dynamic analyses were performed to generate fragility curves for collapse due to overturning of the studied structures. The results show that peak drifts can be accurately predicted. Peak axial loads in frame members are increased due to the vertical inertia forces induced upon rocking. The fragility curves show that acceptable margins against collapse by overturning is achieved for G-CRBFs.