Analysis and modelling of the seismic behaviour of high ... - Ingegneria

4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS
The possible factors that have influenced the overestimation of the design
overstrength factor should be:
• the partial safety factors used during the design of the structure;
• the design action amplification for accidental torsional effects;
• the interstorey drift limits that should be satisfied in the design;
• the difference between the design strength and the actual strength value of the
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materials;
4.10 Pseudo-Dynamic tests on the prototype structure
It is worthwhile to emphasize that quasi-static cyclic loading tests are no doubt the
most effective tests to acquire data on the capacity of the structure, such as the
maximum resistance and ductility. Nonetheless, to evaluate the performance of the
structure in terms of complex hysteretic behaviour under earthquake-like loading
pseudo-dynamic tests (PsD) are needed. Pre-test analyses of the specimen and
post-test comparisons will be performed.
Basing on the Performance Based Seismic Engineering (PBSE) method, the
values of the peak ground acceleration (PGA) employed for the pseudo-dynamic
tests were chosen, as reported in Table 4.9.
PsD Tests PGA [g] OBJECTIVES
1 0,10 Elastic Test
2 0,25 Serviceability Limit State: SLS
3 1,40
Ultimate Limit State: ULS (joints’
maximum rotation equal to 35 mrad)
4 1,80 Collapse Limit State CLS
Table 4.9. Values of the PGA’s for the pseudo-dynamic tests
1. Snap back PsD test with a value of acceleration equal to 0.1g was performed
to measure dynamic elastic properties of the frame, viz. eigenvalues,
eigenvectors and equivalent viscous damping as well as to verify the precision
of the PsD algorithm.
2. The objective of the second test was to lead the structure to the elastic limit, so
as provided by the EC8 for the structural Serviceability Limit State. As a result,
the basic vertical- and lateral force resisting system of the structure
substantially retain original strength and stiffness. Only limited structural