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Fig. 3. Five-story flat-slab building, (a) elevation, (b) plan. A five story flat-slab structure is used as the generic system for this study. Preliminary analysis of three, five and seven story versions had indicated rather insignifi- cant differences in the inelastic dynamic analysis results. This building is considered mid-rise. The reason for choosing a mid-rise building is twofold. Because of the inherent flexibility of flat-slab buildings, it may not be possible to satisfy the drift demands in high-rise construction. On the other hand, low-rise buildings would be sufficiently stiff and may not warrant special consideration. The selected dimensions of the building

Figure 3 Five-story flat-slab building, (a) elevation, (b) plan. A five story flat-slab structure is used as the generic system for this study. Preliminary analysis of three, five and seven story versions had indicated rather insignifi- cant differences in the inelastic dynamic analysis results. This building is considered mid-rise. The reason for choosing a mid-rise building is twofold. Because of the inherent flexibility of flat-slab buildings, it may not be possible to satisfy the drift demands in high-rise construction. On the other hand, low-rise buildings would be sufficiently stiff and may not warrant special consideration. The selected dimensions of the building

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Fig. 2. The methodology used in the derivation of fragility curves.
Fig. 2. The methodology used in the derivation of fragility curves.
Fig. 1. Illustration of a typical flat-slab structural form.
Fig. 1. Illustration of a typical flat-slab structural form.
Fig. 4. Typical slab—beam section of the flat-slab building (symbol 5@12 denotes five reinforcing bars with a diameter of 12 mm and @10/15 denotes tied reinforcement with a diameter of 10 mm and having a spacing of 15 cm). One of the main concerns in flat-slab construction is the control of excessive lateral drift. This concern was addressed by placing masonry infill walls, which have high in-plane stiffness. At low levels of lateral force, frame and infill wall act in a fully composite fashion. However, as the lateral force level increases, the frame attempts to deform in a flexural mode while the infill attempts to deform in a shear mode. As a result, the
Fig. 4. Typical slab—beam section of the flat-slab building (symbol 5@12 denotes five reinforcing bars with a diameter of 12 mm and @10/15 denotes tied reinforcement with a diameter of 10 mm and having a spacing of 15 cm). One of the main concerns in flat-slab construction is the control of excessive lateral drift. This concern was addressed by placing masonry infill walls, which have high in-plane stiffness. At low levels of lateral force, frame and infill wall act in a fully composite fashion. However, as the lateral force level increases, the frame attempts to deform in a flexural mode while the infill attempts to deform in a shear mode. As a result, the
Fig. 5. Masonry infill frame sub-assemblages. culation of the confinement factor, the simple relation- ship proposed by Park et al. [16] is used, and is given below:
Fig. 5. Masonry infill frame sub-assemblages. culation of the confinement factor, the simple relation- ship proposed by Park et al. [16] is used, and is given below:
Characteristics of the selected ground motions Table |
Characteristics of the selected ground motions Table |
Fig. 6. Mesh configuration of the flat-slab model in ZeusNL.
Fig. 6. Mesh configuration of the flat-slab model in ZeusNL.
Fig. 7. Comparison of elastic spectra with the code spectrum.
Fig. 7. Comparison of elastic spectra with the code spectrum.
Fig. 9. Mapping from local limit states to global limit states, (a) story shear versus story drift curve, (b) yield limit state, (c) ultimate limit state.
Fig. 9. Mapping from local limit states to global limit states, (a) story shear versus story drift curve, (b) yield limit state, (c) ultimate limit state.
Fig. 8. Pushover analysis results, (a) capacity curve, (b) plastic hinge formation.
Fig. 8. Pushover analysis results, (a) capacity curve, (b) plastic hinge formation.
Limit states and corresponding interstory drift ratios Table 2 8. Material uncertainty
Limit states and corresponding interstory drift ratios Table 2 8. Material uncertainty
Fig. 10. Displacement spectra (€=5%) of the selected ground motions.
Fig. 10. Displacement spectra (€=5%) of the selected ground motions.
Fig. 11. Damage versus motion relationship for the flat-slat structure. P(Sa > LS4) = 0.011
Fig. 11. Damage versus motion relationship for the flat-slat structure. P(Sa > LS4) = 0.011
Fig. 12. Lognormal statistical distributions for two different levels of seismic intensity, (a) intensity level 1 (Sq = 30 mm), (b) intensity level 2 (Sy = 60 mm).
Fig. 12. Lognormal statistical distributions for two different levels of seismic intensity, (a) intensity level 1 (Sq = 30 mm), (b) intensity level 2 (Sy = 60 mm).
Fig. 13. Vulnerability curves for the flat-slab structure.
Fig. 13. Vulnerability curves for the flat-slab structure.
Fig. 15. Acceleration-based fragility curves for the framed structure This was accomplished by converting the spectral values and then matching the converted values with the corresponding response (interstory drift) values. The spectral acceleration-based fragility curves are shown in Fig. 15. Figs. 16 and 17 show the comparison of the curves obtained for framed structures against the HH curves and the SK curves developed by Hwang and Huo [26] and Singhal and Kiremidjian [27], respect- ively. The HH curves in Fig. 16 were developed for low-rise (1-3 story) concrete frames. Four damage states were considered in terms of maximum story drift ratio, Omax: (1) no damage, when oOmax < 0.2%, (2) insignificant damage, when 0.2% < dmax < 0.5%, (3) moderate damage, when 0.5% < dmax < 1.0% and (4) heavy damage, when dmax < 1.0%. More information about these fragility curves are discussed in Table 3.
Fig. 15. Acceleration-based fragility curves for the framed structure This was accomplished by converting the spectral values and then matching the converted values with the corresponding response (interstory drift) values. The spectral acceleration-based fragility curves are shown in Fig. 15. Figs. 16 and 17 show the comparison of the curves obtained for framed structures against the HH curves and the SK curves developed by Hwang and Huo [26] and Singhal and Kiremidjian [27], respect- ively. The HH curves in Fig. 16 were developed for low-rise (1-3 story) concrete frames. Four damage states were considered in terms of maximum story drift ratio, Omax: (1) no damage, when oOmax < 0.2%, (2) insignificant damage, when 0.2% < dmax < 0.5%, (3) moderate damage, when 0.5% < dmax < 1.0% and (4) heavy damage, when dmax < 1.0%. More information about these fragility curves are discussed in Table 3.
Fig. 14. Comparison of fragility curves for flat-slab and framed structures.
Fig. 14. Comparison of fragility curves for flat-slab and framed structures.
Fig. 16. Comparison of the study curves for framed structure with Hwang and Huo.
Fig. 16. Comparison of the study curves for framed structure with Hwang and Huo.
Fig. 17. Comparison of the study curves for framed structure with Singhal and Kremidjian.
Fig. 17. Comparison of the study curves for framed structure with Singhal and Kremidjian.