Effects of Fire-Damage on the Nonlinear Response of R.C. Base-Isolated Buildings Under Near-Fault Earthquakes


Abstract eng:
The increase in the deformability of a fire-damaged base-isolated building may lead to an amplification in the structural response under the long-duration horizontal pulses of near-fault earthquakes. Moreover, high values of the peak acceleration ratio, defined as the ratio between the peak value of the vertical acceleration and the analogous value of the horizontal acceleration, can become critical once the strength level of a fire-weakened base-isolated structure is reduced. To study the nonlinear seismic response following fire, a numerical investigation is carried out on six-storey r.c. base-isolated structures, composed of a basement and five storeys above the ground level, designed in line with the Italian seismic code. The baseisolation system is constituted of High-Damping-Laminated-Rubber Bearings (HDLRBs). Different values of fire resistance and opening factor representing the amount of ventilation are considered, in line with the parametric temperature-time fire curve proposed by Eurocode 1. Three fire scenarios are examined, with the fire compartment confined to the area of the base-isolated level (i.e. F0) and first (i.e. F1) and fifth (i.e. F5) levels of the superstructure. A numerical investigation is carried out by means of thermal-mechanical mapping analysis, with reduced mechanical properties of both r.c. crosssections, in line with the 500°C isotherm method proposed by Eurocode 2, and HDLRBs, in line with a proposed 200°C isotherm method. A nonlinear incremental dynamic analysis considers the horizontal and vertical components of near-fault earthquakes. Plastic conditions are assessed at the potential critical sections of the beams (i.e. end sections of the subelements in which a beam is discretized) and columns (i.e. end sections). The response of a HDLRB is simulated with a viscoelastic model with variable stiffness properties in the horizontal and vertical directions, depending on the axial force and lateral deformation.

Contributors:
Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
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Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


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