In order to study the dynamic behaviour of construction,specifically seismic response of structures,as many researchers did,we have resorted to modelling methods,based on the scaled internal forces.Therefore,this rese...In order to study the dynamic behaviour of construction,specifically seismic response of structures,as many researchers did,we have resorted to modelling methods,based on the scaled internal forces.Therefore,this research includes results of an experimental investigation aimed to establish the possibility of realistic simulations of the cyclic response of small-scale models of one bay,one-storey reinforced concrete frames with masonry infills as a preliminary step for simulating the dynamic response of such structural.So,the specimens constructed were 1:9 scale R/C frames.These 1:9 scale infill frames were constructed with prototype materials and were tested in an extensive experimental sequence representing specimens of a scale near the prototype(1:3).The tested laboratory models include 1:3 scale infilled R/C frames that were built from original material such as steel,concrete and masonry infills(hollow masonry units and mortar).With the same scale,geometry and construction materials used for the construction of a 1:3 scale 5-story three dimensional building.This program consisted of 16 models,5 bare and 11 masonry infilled.all models refer to single-storey one-bay 1:9 scale as for the original structure and a one third of the scale(1:3)as for the prototype(1:3).The reinforced concrete specimens were designed in such a way as to prevent shear failure of the columns.Finally,the present paper was carried out in the Laboratory of Strength of Materials and Structures in the Department of Civil Engineering at Aristotle University of Thessaloniki.展开更多
The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete （r.c.） spatial frames, because only far-fault ground motions a...The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete （r.c.） spatial frames, because only far-fault ground motions are considered in the seismic codes. Strong near-fault earth- quakes are characterized by long-duration （horizontal） pulses and high values of the ratio ~PGA of the peak value of the vertical acceleration, PGAv, to the analogous value of the horizontal acceleration, PGAH, which can become critical for girders and columns. In this work, six- and twelve-storey r.c. spatial frames are designed according to the provisions of the Italian seismic code, considering the horizontal seismic loads acting （besides the gravity loads） alone or in combination with the vertical ones. The non- linear seismic analysis of the test structures is performed using a step-by-step procedure based on a two-parameter implicit integration scheme and an initial stress-like itera- tive procedure. A lumped plasticity model based on the Haar-K^n~m principle is adopted to model the inelastic behaviour of the frame members. For the numerical investigation, five near-fault ground motions with high values of the acceleration ratio C^p6A are considered. Moreover, following recent seismological studies, which allow the extraction of the largest （horizontal） pulse from a near-fault ground motion, five pulse-type （horizontal） ground motions are selected by comparing the original ground motion with the residual motion after the pulse has been extracted. The results of the nonlinear dynamic analysis carried out on the test structures highlighted thathorizontal and vertical components of near-fault ground motions may require additional consideration in the seis- mic codes.展开更多
文摘In order to study the dynamic behaviour of construction,specifically seismic response of structures,as many researchers did,we have resorted to modelling methods,based on the scaled internal forces.Therefore,this research includes results of an experimental investigation aimed to establish the possibility of realistic simulations of the cyclic response of small-scale models of one bay,one-storey reinforced concrete frames with masonry infills as a preliminary step for simulating the dynamic response of such structural.So,the specimens constructed were 1:9 scale R/C frames.These 1:9 scale infill frames were constructed with prototype materials and were tested in an extensive experimental sequence representing specimens of a scale near the prototype(1:3).The tested laboratory models include 1:3 scale infilled R/C frames that were built from original material such as steel,concrete and masonry infills(hollow masonry units and mortar).With the same scale,geometry and construction materials used for the construction of a 1:3 scale 5-story three dimensional building.This program consisted of 16 models,5 bare and 11 masonry infilled.all models refer to single-storey one-bay 1:9 scale as for the original structure and a one third of the scale(1:3)as for the prototype(1:3).The reinforced concrete specimens were designed in such a way as to prevent shear failure of the columns.Finally,the present paper was carried out in the Laboratory of Strength of Materials and Structures in the Department of Civil Engineering at Aristotle University of Thessaloniki.
文摘The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete （r.c.） spatial frames, because only far-fault ground motions are considered in the seismic codes. Strong near-fault earth- quakes are characterized by long-duration （horizontal） pulses and high values of the ratio ~PGA of the peak value of the vertical acceleration, PGAv, to the analogous value of the horizontal acceleration, PGAH, which can become critical for girders and columns. In this work, six- and twelve-storey r.c. spatial frames are designed according to the provisions of the Italian seismic code, considering the horizontal seismic loads acting （besides the gravity loads） alone or in combination with the vertical ones. The non- linear seismic analysis of the test structures is performed using a step-by-step procedure based on a two-parameter implicit integration scheme and an initial stress-like itera- tive procedure. A lumped plasticity model based on the Haar-K^n~m principle is adopted to model the inelastic behaviour of the frame members. For the numerical investigation, five near-fault ground motions with high values of the acceleration ratio C^p6A are considered. Moreover, following recent seismological studies, which allow the extraction of the largest （horizontal） pulse from a near-fault ground motion, five pulse-type （horizontal） ground motions are selected by comparing the original ground motion with the residual motion after the pulse has been extracted. The results of the nonlinear dynamic analysis carried out on the test structures highlighted thathorizontal and vertical components of near-fault ground motions may require additional consideration in the seis- mic codes.
