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

4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS
semi-rigid partial-strength beam-to-column joints and partially encased columns in
earthquake-prone regions, the project aims at calibrating design rules affecting the
aforementioned components and the participation of the concrete slab in the
relevant transfer mechanisms. Another objective of the project was also the
development of non-linear mechanical models combined with smooth hysteretic
and damage models of composite members, joints and frames capable of
reproducing the experimental response. As a matter of fact, it is intended to
calibrate damage models for members and connections and correlate the damage
obtained at the inter-storey levels with the damage obtained at the members and
connections.
A basic construction typology was selected for the study that includes regular
composite beams connected to partially encased composite columns with partially
restrained end plate connections. Within the project, a prototype 2-storey, 4-bay
structure was designed to obtain representative dimensions, member sizes and
connection details to examine the seismic behaviour of the structural system.
Pseudo-dynamic testing of a full-scale specimen including 3 of the 5 frames of the
prototype structure will be conducted in 2003 at the JRC ELSA Unit in Ispra (Italy)
to examine its seismic response.
4.3 Description of the prototype structure
The prototype structure considered for this study is shown in Figure 4.1. It is a 2-
storey, 12.0 m x 12.0 m x 7.0 m structure, which includes five two-bay moment
resisting frames with unequal spans (5 m + 7 m). All five moment resisting frames
are identical and one frame is illustrated in Figure 4.2. In the direction
perpendicular to the moment resisting frames, simply supported secondary beams
are used at column lines to link the frames together and lateral resistance is
provided by two concentrically braced steel frames located along the exterior walls.
Only the behaviour of the structure in the direction parallel to the moment resisting
frames (X direction in Figure 4.1) is considered herein. The frame to be tested at
Ispra only includes the three interior moment resisting frames, along with the
secondary beams and the transverse cross bracing.
The columns are partially encased composite columns, which guarantee significant
structural efficiency with respect to static, seismic loads and fire resistance. They
are fixed at their base and continuous over the full height of the structure. The steel
profiles are HEB260 and HEB280 for the exterior and interior columns,
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