EXAMPLE 6. BUILDING VALUATION & REDESIGN STUDY

EXAMPLE 6: "STUDY FOR THE VALUATION AND REDESIGN OF A BUILDING ACCORDING TO THE CANC. 15 4.7 LOCAL INDICATORS m The local indices m express the available local plasticity in the control areas of the linear elements. The local index m is defined as the ratio of the design value of the limiting strain depending on the level of performance to the corresponding value of the yielding strain of the linear member (CEE § 4.7) : / / = = The deformation magnitude taken into account in the calculation of the m indices is - the chord angles of twist θ, for reinforced concrete members, and - the angular deformations c, for wall fillings. ▪ At performance level A, the load-bearing structure (and the wall fillings) is expected to behave quasi-elastic, i.e. without the development of meteorological deformations. It is valid that θd≤ θy (i.e. m≈ 1.0), or respectively using the single behaviour index 1.0 ≤ q ≤ 1.5. ▪ At performance level B, the load-bearing structure develops significant post-tensioning deformations over a large area, but has sufficient and reliable margins against possible exhaustion of available failure strains. For the primary elements it holds that θd ≈ 0,5(θy + θu)/ γRd, while for the secondary elements θd ≈ θu/γRd. ▪ At performance level C, the load-bearing structure develops large metamorphic deformations, over a large area, reaching even the exhaustion of the available failure deformations, but without risk of collapse under gravity loads. It holds for primary elements that θd ≈ θu / γRd, while for secondary elements θd ≈ θu. 4.4.1.3 Response spectra Generally, the response spectra in terms of acceleration, according to EC 8-1, are used as a function of the building's eigenperiod T and the critical viscous damping rate ξ or the behaviour index q. If linear analysis methods are applied, with a global behaviour index q, the "design spectra", Sd(T), are used. In case of application of non-linear methods of analysis, as well as linear methods using a local index m, the "elastic spectra", Se(T), are used. In very specific cases, and only for the valuation of an existing structure, other approximate or empirical methods may be used. 4.4.1.4 Stiffness Where more precise data are not available, stiffness values according to the Table below may be used. 4.4.2 Combinations of actions