This paper contains ground-motion prediction equations (GMPEs) for average horizontal-component ground motions as a function of earthquake magnitude, distance from source to site, local average shear-wave velocity, and fault type. Our equations are for peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped pseudo-absolute-acceleration spectra (PSA) at periods between 0.01 s and 10 s. They were derived by empirical regression of an extensive strong-motion database compiled by the “PEER NGA” (Pacific Earthquake Engineering Research Center’s Next Generation Attenuation) project. For periods less than 1s , the analysis used 1,574 records from 58 mainshocks in the distance range from 0 km to 400 km (the number of available data decreased as period increased). The primary predictor variables are moment magnitude M, closest horizontal distance to the surface projection of the fault plane R JB , and the time-averaged shear-wave velocity from the surface to 30 m VS30. The equations are applicable for M =5–8 , RJB 200 km, and VS30= 180– 1300 m / s. DOI: 10.1193/1.2830434

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Ground-motion prediction equations for the average horizontal component of PGA, PGV, and 5%-damped PSA at spectral periods between 0.01 s and 10.0 s

We present a new empirical ground motion model for PGA, PGV, PGD and 5% damped linear elastic response spectra for periods ranging from 0.01– 10 s. The model was developed as part of the PEER Next Generation Attenuation (NGA) project. We used a subset of the PEER NGA database for which we excluded recordings and earthquakes that were believed to be inappropriate for estimating free-field ground motions from shallow earthquake mainshocks in active tectonic regimes. We developed relations for both the median and standard deviation of the geometric mean horizontal component of ground motion that we consider to be valid for magnitudes ranging from 4.0 up to 7.5–8.5 (depending on fault mechanism) and distances ranging from 0 – 200 km. The model explicitly includes the effects of magnitude saturation, magnitude-dependent attenuation, style of faulting, rupture depth, hanging-wall geometry, linear and nonlinear site response, 3-D basin response, and inter-event and intra-event variability. Soil nonlinearity causes the intra-event standard deviation to depend on the amplitude of PGA on reference rock rather than on magnitude, which leads to a decrease in aleatory uncertainty at high levels of ground shaking for sites located on soil. DOI: 10.1193/1.2857546

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NGA Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01 to 10 s

The true performance of ground-motion prediction equations is often not fully appreciated until they are used in practice for seismic hazard analyses and applied to a wide range of scenarios and exceedance levels. This has been the case for equations published recently for the prediction of peak ground velocity (PGV), peak ground acceleration (PGA), and response spectral ordinates in Europe, the Middle East, and the Mediterranean (Akkar and Bommer 2007a,b). This paper presents an update that corrects the shortcomings identified in those equations, which are primarily, but not exclusively, related to the model for the ground-motion variability.

Strong-motion recording networks in Europe and the Middle East were first installed much later than in the United States and Japan but have grown considerably over the last four decades. The databanks of strong-motion data have grown in parallel with the accelerograph networks, and in addition to national collections there have been concerted efforts over more than two decades to develop and maintain a European database of associated metadata ( e.g. , Ambraseys et al. 2004).

As the database of strong-motion records from Europe, the Mediterranean region, and the Middle East has expanded, there have been two distinct trends in terms of developing empirical ground-motion prediction equations (GMPEs): equations derived from a large dataset covering several countries, generally of moderate-to-high seismicity; and equations derived from local databanks for application within national borders. We refer to the former as pan-European models, noting that this is for expedience since the equations are really derived for southern Europe, the Maghreb (North Africa), and the active areas of the Middle East. The history of the development of both pan-European and national equations is discussed by Bommer et al. (2010), who also review studies that consider the arguments for and against the existence of consistent regional …

Empirical Equations for the Prediction of PGA, PGV, and Spectral Accelerations in Europe, the Mediterranean Region, and the Middle East

Seismic Rehabilitation of Existing Buildings

In code-based seismic design and assessment it is often allowed the use of real records as an input for nonlinear dynamic analysis. On the other hand, international seismic guidelines, concerning this issue, have been found hardly applicable by practitioners. This is related to both the difficulty in rationally relating the ground motions to the hazard at the site and the required selection criteria, which do not favor the use of real records, but rather various types of spectrum matching signals. To overcome some of these obstacles a software tool for code-based real records selection was developed. REXEL, freely available at the website of the Italian network of earthquake engineering university labs (http://www.reluis.it/index_eng.html), allows to search for suites of waveforms, currently from the European Strong-motion Database, compatible to reference spectra being either user-defined or automatically generated according to Eurocode 8 and the recently released new Italian seismic code. The selection reflects the provisions of the considered codes and others found to be important by recent research on the topic. In the paper, record selection criteria are briefly reviewed first, and then the algorithms implemented in the software are discussed. Finally, via some examples, it is shown how REXEL can effectively be a contribution to code-based real records selection for seismic structural analysis.

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REXEL: computer aided record selection for code-based seismic structural analysis

Most residential buildings that were constructed during the last century in Switzerland are 2-6 storey unreinforced masonry (URM) structures. At the beginning of the century, houses were constructed with timber floors and small bricks. This type of construction was later replaced by one which used larger, perforated bricks and reinforced concrete slabs. When assessing the seismic risk in Switzerland, a good understanding of the performance of the different types of URM buildings is mandatory. Numerical analyses have shown that spandrel beams have a significant influence on the seismic behaviour of URM structures since they influence strongly the stiffness and strength of the structure. However, until today, spandrel elements are often not considered when modelling URM structures because only very limited information on their force-deformation characteristics is available. For this reason a research project was initiated that aims at investigating the behaviour of different configurations of spandrel beams in URM walls using numerical and experimental methods. As part of the project large-scale, quasi-static monotonic and cyclic tests of spandrel beams were carried out. The test units represented spandrel beams in modern URM structures with reinforced concrete slabs or ring beams as well as spandrel beams in older URM structures with wooden floors. This paper presents the results of the test campaign on masonry spandrels in URM structures with wooden floors. Four spandrels were subjected to a quasi-static cyclic loading regime. The masonry spandrels were supported by either a timber lintel or a shallow masonry arch.

Seismic behaviour of different types of masonry spandrels

Keywords: Reinforced concrete walls ; Plan-asymmetric buildings ; Torsion Reference EPFL-CONF-224467 Record created on 2017-01-17, modified on 2017-01-23

Application of a recently proposed displacement-based assessment procedure for asymmetric-plan RC wall buildings

In unreinforced masonry (URM) walls the vertical piers are connected by horizontal spandrel elements. Numerical simulations have shown that spandrels influence significantly the global wall behaviour under seismic loading. Despite their importance, experimental data on the cyclic behaviour of these spandrels is very scarce. The lack of experimental data prevented in the past the validation of numerical and mechanical models regarding the cyclic behaviour of masonry spandrels. For this reason a research program was initiated in which the cyclic behaviour of masonry spandrels was investigated experimentally and numerically. Within this program different configurations of masonry spandrels were tested under quasi-static monotonic and cyclic loading. The spandrel configurations that were investigated included pure masonry spandrels and masonry spandrels which also comprise a reinforced concrete (RC) beam or slab. The latter represents spandrels in newer masonry buildings with RC slabs or RC ring beams while the former can be found in older masonry buildings. This paper presents preliminary results of the experimental program as well as some selected results of the accompanying numerical study.

Experimental investigation of the cyclic behaviour of unreinforced masonry spandrels

Cyclic test data of five URM walls at half-scale

The current provisions for the braking force in the Eurocodes are much more demanding than previously enforced national codes from most European countries. Hence, safety assessments of existing bridges may show a lack of compliance with the new safety requirements of current maintenance codes, making the relevant authorities responsible for their strengthening. The current load model for the braking force was derived from a deterministic evaluation of traffic configurations with characteristics that do not correspond with actual traffic measurements. This procedure differs from models describing vertical traffic loads, where the effects of traffic were analysed within a probabilistic framework in compliance with the partial safety factor design method. This paper investigates the advantages, limitations and hypotheses of a probabilistic model for the braking force when compared with deterministic models. Original results for the characteristic value of the braking force on road bridges are presented, which consider a realistic time-history of bridge crossing vehicles generated by a traffic microsimulation tool with input data from a Swiss Weigh-In-Motion station. The results are compared with the braking force of the Eurocodes, highlighting the role of the probability of braking and the influence of the dynamic characteristics of bridges on the characteristic value of the braking force.

Katrin Beyer

Papers

Seismic behaviour of different types of masonry spandrels

Application of a recently proposed displacement-based assessment procedure for asymmetric-plan RC wall buildings

Experimental investigation of the cyclic behaviour of unreinforced masonry spandrels

Cyclic test data of five URM walls at half-scale

Deriving a Load Model for the Braking Force on Road Bridges: Comparison Between a Deterministic and a Probabilistic Approach