PGA contours for the 30/08/1986 & 30/05/1990 earthquakes:without (dotted line) and with (continuous line) SMBRS-DU stations*

* Rectangle height in SMBRS-DU stations ���� proportional with no. of stories- recorded > predicted by interp. surface w/o SMBRS-DU records ���� magenta- recorded < predicted ���� blue- no prediction available ���� white

�Recorded / predicted values: 0.8 … 1.6 (1986), 0.5 … 1.4 (1990)�Very weak correlation of recorded/predicted ratio with number of

stories: increasing trend (1986), decreasing trend (1990)

Spatial distribution of PGA values for the 30/08/1986 and 30/05/1990 earthquakes without and with inclusion of SMBRS-DU stations

�Contours obtained by including the SMBRS-DU-type stations maintain the general pattern and the orientation determined in their absence

�Possible explanations: low amplification or deamplification of free-field motions due to building influence and/or relatively small number of stations situated in positions that would influence significantly the shape of the interpolation surface

Table 1. Characteristics of buildings with SMRSBTable 1. Characteristics of buildings with SMRSB--DUDU--type stations.type stations.Group A: buildings with base and top instrumentsGroup A: buildings with base and top instruments

Table 2. Characteristics of buildings with SMRSBTable 2. Characteristics of buildings with SMRSB--DUDU--type stations.type stations.

Group B: buildings with base instruments onlyGroup B: buildings with base instruments only

* B = basement, GF = ground floor, S = story, TS = top story; *** B = basement, GF = ground floor, S = story, TS = top story; ** period estimations: period estimations: DemetriuDemetriu, 2002, 2002

AN ANALYSIS OF THE USABILITY OFAN ANALYSIS OF THE USABILITY OF

STRONG GROUND MOTION RECORDS OBTAINED FROMSTRONG GROUND MOTION RECORDS OBTAINED FROM

STATIONS LOCATED IN DENSELY URBANIZED AREAS IN ROMANIASTATIONS LOCATED IN DENSELY URBANIZED AREAS IN ROMANIA

IolandaIolanda--Gabriela CRAIFALEANUGabriela CRAIFALEANU1,21,2, , IoanIoan SorinSorin BORCIABORCIA11

1 National Institute for Research and Development in Constructions, Urbanism and Sustainable Spatial Development,

URBAN-INCERC, INCERC Bucharest Branch & European Center for Buildings Rehabilitation, ECBR, Bucharest, Romania2 Technical University of Civil Engineering Bucharest, Romania

� Research performed during the past decades on Romanian Vrancea earthquakes has systematically excluded records from stations located in multi-storey mid-rise buildings

� Several locations all across the country where these are the only available type of records ���� seismic stations in densely urbanized areas in Romania, similar to the SMBRS-DU category in the COSMOS, 2001 classification

� Current phase of the study ���� discussion based only on actually recorded PGA values - maps could provide a first indication of the potential outcomes of SMBRS-DU stations inclusion

� Generation of PGA contour maps and assessment of modification ofinterpolation surfaces, resulting from the inclusion of SMBRS-DU stations

� Buildings can either amplify or deamplify free-field ground motions (Stewart, 2000, Pandey, 2012) ���� future studies planned for the subsequent phases of the research, to assess individually the effect of considered buildings on ground motions recorded at SMBRS-DU stations

Seismic stations (SMRS-SB & SMBRS-DU) that provided records from

the 30/08/1986 and 30/05/1990 Vrancea earthquakes

No. Station Station

Code

No. of

Stories*

Instrument

Position Structure Type Estimated T

~

(s)

1 Bacau Cornisa BAC1 B+GF+10S RC Shear Walls 0.48; 0.76

2 Braila BRL1 B+GF+11S RC frames w. Masonry Infill 0.87…1.04; 0.92…0.95

3 Bucharest – Balta Alba BLA1 B+GF+10S RC Shear Walls 0.66; 0.73

4 Craiova CRV1 B+GF+7S RC frames w. Masonry Infill 0.75; 0.99

5 Galati IPJ GLT2 B+GF+9S RC frames w. Masonry Infill 1; 1.06

6 Galati Tiglina I1 GLT1 B+GF+10S RC Shear Walls 0.69; 0.74

7 Ploiesti-Vest PLS B+GF+10S

B & TS*

RC Shear Walls 0.61…0.72; 0.81…1.02

No. Station Station Code No. of Stories* Instrument

Position

1 Iasi City Centre IAS2 B+GF+4S

2 Brasov BRS1 B+GF+8S

3 Bucharest - Carlton CRL 2B+GF+6S

4 Buzau BUZ B+GF+10S

5 Campulung Muscel CMP B+GF+6S

6 Constanta CNT B+GF+7S

7 Focsani IPJ FOC2 B+GF+3S

8 Sibiu SIB B+GF+6S

9 Slobozia SLB** B+GF+4S

10 Tulcea – City Hall TLC2 B+GF+4S

11 Vaslui VLS** B+GF+4S

B or GF**

w/o SMBRS-DU stations with SMBRS-DU stations

w/o SMBRS-DU stations with SMBRS-DU stations

30/08/1986

30/05/1990

ACKNOWLEDGEMENTSFunding for the research presented above was partly provided by the Romanian Ministry of National Education, UEFISCDI Agency, under Contract No. 72/2012, Project BIGSEES. This support is gratefully acknowledged.

�To eliminate the influence of the different number of stations that recorded each event ����interpolation only for stations that recorded both earthquakes, w/o SMBRS-DU stations, for the city of Bucharest

Bucharest

30/08/1986 30/05/1990

�PGA: values recorded vs. predicted by interpolation at SMBRS-DU stations ���� the previously observed amplification / deamplificationtendencies are not modified ���� they are probably determined by the differences between the frequency content of ground motions recorded during the 1986 and 1990 earthquakes (Borcia & Sandi, 2011)

**