Interior wide beam-column connections in existing RC frames subjected to lateral earthquake loading

Abstract

The seismic performance of two RC interior wide beam-column connections representative of existing frames designed and detailed according to past construction practices in the moderate-seismicity Mediterranean area was investigated experimentally. The specimens were subjected to axial loads, moderate levels of gravity loading and cyclic displacements up to failure. The specimens exhibited a "strong column-weak beam" type of flexural yielding mechanism. The wide beams did not reach the expected capacities corresponding to the formation of a full-width plastic hinge. The wide-beam longitudinal bars exhibited significant slippage, and the transverse beams underwent severe torsion cracking and even failure; this caused severe pinching in the load versus displacement hysteretic loops and exacerbated the intrinsic flexibility of this type of connection. The average drift ratios at first yielding of the wide beam longitudinal reinforcement and at failure were 2.7 and 4.5%, respectively. The displacement ductility ratio was about 2.8. The ultimate energy dissipation capacity of each specimen-obtained by dividing the total plastic strain energy by the product of the yield load and yield displacement-was approximately 9, which is about one fourth of the value recommended for providing adequate seismic performance. Finally, a simple approach is suggested for prediction of the bending capacity of existing connections.

Structural Resistance of Reinforced Concrete Buildings in Areas of Moderate Seismicity and Assessment of Strategies for Structural Improvement

“…[46] the joints/connections between the columns and the wide beams were assumed to be rigid, and the hysteretic behaviour of the stress distribution was modelled by using fibres which were defined based on the material properties and shape of the structural elements (each element section was discretised into 300 fibres). The analysis results were compared to the experimental results available in Benavent-Climent et al [29] and satisfactory agreement was obtained.…”

“…Recommendations for future constructions will be proposed based on the findings of this study. The results of the analyses will be compared with those from previous studies (e.g., [10,13,28,29]). …”

Would RC wide-beam buildings in Spain have survived Lorca earthquake (11-05-2011)?

“…Joint panels are assumed to be infinitely rigid. Values of µ ϕ are identified from experiments on beam-column connections representative of real constructions; therefore, take into account confinement contribution Methods proposed in [Benavent-Climent 2009a, 2009b are applied to estimate influence of incomplete torsion capacity of outer zones of wide beams. In both non code-compliant and codecompliant buildings, it is checked that joints do not fail prior than beams or columns; as well, it is verified that, in any section of members, shear failure do not precede flexural one.…”

Seismic performances and behaviour factor of wide-beam and deep-beam RC frames

“…(6,7) DCH (q=3.5) ≈30dbi ≈48 (6,7) -0.25hc (9,11) 0.25hc 0.25hc (16) min{L/8;8hf;hb; hc·{0.5;0.75} (18) }; min{L/8;8hf;3hb} (19) 0.25hc (22) 90% (24) Spain: NCSE-02 (2002) [14] -33%) ≈36dbi ≈55 (6,7) min{0.5hb; 0.5bc (8) } (10) -0.5bc (14) 0.25hc (8) hf·{0;2;0;2} (17) - (21 Current version of EC8 does not cover flat slab, 1.5 is the basic assumption for elastic design; new version in progress (1) For DLS but obtained from ULS displacements (2) Specific for ULS (3) Obtained from specific DLS demand spectrum (4) Depending on ag and number of storeys (5) Sufficient stiffness to ensure frame -not cantilever-behaviour in all columns (6) Formulation depending in most of the cases on ductility class, material strengths, axial load, reinforcement ratios and location of the joint (7) Considering ϕw=16mm (8) Edge beams not explicitly considered (9) Not for low-ductility design (10) Referred to gross section, not to web (11) Referred to the 90% of the required flexural reinforcement; remaining 10% within (19) (12) Required transverse beam for external connections or internal connections with moment inversion (13) Not mandatory, only for taking advantage of the column compression on the bond behaviour (14) Higher values only if proper perpendicular reinforcement is placed (15) Further research is needed (16) Also reciprocal requirement for columns in the case of wide column -narrow beam connection (17) Exterior connection with and without transverse beam, and anal...…”