Performance-Based Seismic Bridge Design (2013) / Chapter Skim
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From page 12... ...
12 CHAPTER THREE REVIEW OF INDUSTRY PRACTICE A literature review of the current seismic design standard of practice for the bridge, building, and waterfront/marine industries was conducted. This chapter provides the results.
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13 required design moments; then these locations are prescriptively detailed to be adequately ductile. The remainder of the bridge, including foundations, superstructure, bearings, abutments, and the nonyielding portion of the columns, is designed to be able to withstand the maximum possible forces -- known as overstrength forces -- that the plastic mechanism would ever be capable of generating.
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14 lae are shown in Figure 4 for SDC B and Figure 5 for SDC C The averaging process used is evident in the figures by the SDC line's position relative to the neighboring lines.
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15 • ASL 1: 0–15 years • ASL 2: 16–50 years • ASL 3: >50 years. The PLs range from PL0 to PL3, and the corresponding expected postdesign earthquake damage levels are as follows: • PL0: No minimum -- No minimum level of performance is specified.
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16 selected approach. The strategy is the overall plan for retrofitting the bridge and may include several approaches made up of different measures.
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17 met, adequate seismic performance is implied in much the same way as in the AASHTO LRFD. The implication is that if the structure meets the code, then life safety is reasonably assured.
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18 way column shear is checked in AASHTO seismic design methods. When checking deformation-controlled elements, maximum inelastic deformations for each performance level are specified.
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19 performance-based earthquake engineering is not a subject that is suitable for "standardization" or "cookbook-ization." Their point is that performance-based earthquake engineering, particularly for rehabilitation of existing structures, must rely on first principles, be done on the merits or lack thereof of each structure, and be performed by appropriately trained and qualified engineers. These issues must be taken into account in the development of any new document purporting to guide the performance-based engineering process.
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20 consequences in terms of human losses, direct economic losses, and indirect economic losses. The framework is outlined in detail in Seismic Performance Assessment of Buildings Volume 1 -- Methodology of the 75% draft of ATC 58-1 (2011)
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21 actual structures designed using the specifications. However, ASCE 43-05, Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities (2005a)
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22 These performance groups are essentially the same as those in the IBC and ASCE 7. The performance group, combined with four design events, is then used to define the maximum level of damage that can be tolerated, as shown in Table 4.
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23 maximum considered earthquake (MCE)
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