TY - JOUR
T1 - Three-storey building retrofit
T2 - rocking isolation versus conventional design
AU - Anastasopoulos, Ioannis
AU - Drosos, Vasileios
AU - Antonaki, Nonika
PY - 2015/7/10
Y1 - 2015/7/10
N2 - Although modern seismic codes have undoubtedly led to safer structures, the seismic vulnerability of metropolitan areas is unavoidably governed by that of older buildings, which constitute the vast majority of the current building stock. Quite alarmingly, even relatively moderate intensity earthquakes have been proven capable of challenging their structural integrity, leading to severe damage or collapse. Therefore, there is an urgent need to assess the vulnerability of existing structures and to evaluate the efficiency of novel retrofit techniques. This paper studies experimentally the seismic performance of an existing three-storey building, retrofitted through addition of shear walls. Emphasis is placed on the foundation of the shear walls, and two design alternatives are comparatively assessed: (a) conventional design according to current seismic codes and (b) 'rocking isolation' by reducing the size of the foundation. A series of reduced-scale shaking table tests are conducted at the Laboratory of Soil Mechanics of the National Technical University of Athens. The physical model encompasses the structural system, along with the foundations, and the soil. The nonlinearity of structural members is simulated through specially designed and carefully calibrated artificial plastic hinges. The vulnerability of the original structure is confirmed, as it is found to collapse with a soft-storey mechanism when subjected to moderate intensity shaking. The conventionally retrofitted structure is proven capable of sustaining larger intensity shaking, and the rocking-isolated structure is shown to offer increased safety margins. Thanks to its inherent self-centering mechanism, the rocking system is characterized by reduced permanent drifts.
AB - Although modern seismic codes have undoubtedly led to safer structures, the seismic vulnerability of metropolitan areas is unavoidably governed by that of older buildings, which constitute the vast majority of the current building stock. Quite alarmingly, even relatively moderate intensity earthquakes have been proven capable of challenging their structural integrity, leading to severe damage or collapse. Therefore, there is an urgent need to assess the vulnerability of existing structures and to evaluate the efficiency of novel retrofit techniques. This paper studies experimentally the seismic performance of an existing three-storey building, retrofitted through addition of shear walls. Emphasis is placed on the foundation of the shear walls, and two design alternatives are comparatively assessed: (a) conventional design according to current seismic codes and (b) 'rocking isolation' by reducing the size of the foundation. A series of reduced-scale shaking table tests are conducted at the Laboratory of Soil Mechanics of the National Technical University of Athens. The physical model encompasses the structural system, along with the foundations, and the soil. The nonlinearity of structural members is simulated through specially designed and carefully calibrated artificial plastic hinges. The vulnerability of the original structure is confirmed, as it is found to collapse with a soft-storey mechanism when subjected to moderate intensity shaking. The conventionally retrofitted structure is proven capable of sustaining larger intensity shaking, and the rocking-isolated structure is shown to offer increased safety margins. Thanks to its inherent self-centering mechanism, the rocking system is characterized by reduced permanent drifts.
KW - Dynamic response
KW - Physical modelling
KW - Rocking
KW - Seismic retrofit
KW - Shaking table testing
UR - http://www.scopus.com/inward/record.url?scp=84929833220&partnerID=8YFLogxK
U2 - 10.1002/eqe.2511
DO - 10.1002/eqe.2511
M3 - Article
AN - SCOPUS:84929833220
VL - 44
SP - 1235
EP - 1254
JO - Earthquake Engineering and Structural Dynamics
JF - Earthquake Engineering and Structural Dynamics
SN - 0098-8847
IS - 8
ER -