Influence of shear deformation of exterior beam-column joints on the quasi-static behavior of RC framed structures

Dias

2017

A reinforced concrete (RC) beam-column (RCBC) joint model for the quasi-static monotonic analysis of cast in situ RC frames is developed and implemented in a finite element analysis program for framed structures. The joint model was developed in the framework of the component method, a method originally developed for steel joints, which consists of three steps: (a) identification of the joint relevant basic components, their interaction, and contribution to overall joint behavior; (b) characterization of the mechanical behavior of each component; and (c) assembling of the components. With regard to the model implementation, the material nonlinear analysis is performed by the fictitious forces method-all the required steps are presented and explained-while the P-Δ method for the geometrical nonlinear analysis of frames is extended to include the beam-column joint model. The paper closes with illustrative and validation examples; while some of these are fully analytical, the others simulate lab-tested subframes subjected to quasi-static monotonic loads.

Section: Introductionmentioning

confidence: 80%

N_{j} = \frac{F_{4} + 2 F_{7} + F_{10}}{2} - \frac{F_{6} + F_{12}}{B} + \frac{h_{c} - C}{2 B} ((), F_{11} - F_{5}) = V_{normalj normalh} + ((), \frac{1}{z_{normalb}} - \frac{1}{B}) ((), F_{6} + F_{12}) + \frac{h_{c} - C}{2 B} ((), F_{11} - F_{5}) .

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Section: Rcbc Joint Modelmentioning

confidence: 99%

Component-based reinforced concrete beam-column joint model

Dias

2017

“…However, regardless of the full or partial strength nature of RCBC joints, the influence of their flexibility on the structure overall quasi‐static behaviour should not be neglected—not to mention their influence on progressive collapse or seismic behaviour, which are beyond the scope of this paper. This is recognized by current technical specifications (e.g., ), which require the inclusion of the effect of beam‐column joints deformation in structural models.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] Consequently, current technical specifications require that the strength of RCBC joints is larger than that of the adjacent columns and beams (full strength joints), that is, a joint must not fail before its adjacent elements 5 -in seismic design this is accomplished through the capacity design principles, which classify RCBC joints as brittle components. [6][7][8] However, regardless of the full or partial strength nature of RCBC joints, the influence of their flexibility on the structure overall quasi-static behaviour should not be neglected 9 -not to mention their influence on progressive collapse 10,11 or seismic behaviour, [12][13][14] which are beyond the scope of this paper. This is recognized by current technical specifications (e.g., 5,15 ), which require the inclusion of the effect of beam-column joints deformation in structural models.…”

Section: Introductionmentioning

confidence: 99%

Simplified assessment of the need for the explicit model of RC beam‐column joints instead of the rigid model

Gomes

2019

The behaviour of reinforced concrete beam‐column (RCBC) joints may have an important influence on the structural behaviour of unbraced framed structures—this explains why current technical specifications require accounting for their deformation. However, the available numerical models for RCBC joints are rather complex, so that, at the end of the day, these joints are commonly modeled using one of two alternative simplified models: the rigid joint model and the centerline joint model. This calls for the development of “Simplified Classification Criteria”, which are simplified procedures to assess the influence of RCBC joints on the structural behaviour, that is, to determine whether a simplified joint model can be employed in the numerical model of the overall structure without leading to major errors in the analysis. This paper focuses on the possibility of using the rigid joint model. As a starting point for the step‐by‐step development of general classification criteria for RCBC joints we employ the basic simplified classification criterion already existing for steel beam‐column joints.

Considering the size and strength of beam‐column joints in the design of RC frames

Dias

2015

Some experimental research studies have reported that longitudinal reinforcement in beams and columns exhibits larger strains inside the joint than at the joint periphery (defined as the intersection of the outer surfaces of beam and column). This may explain why several technical specifications and state‐of‐the‐art programs recommend basing the design of beams and columns on internal force values larger than those at the joint periphery. These results and procedures are questionable and are investigated in this paper. The non‐linear finite element analysis presented here for reinforced concrete frames under gravity and quasi‐static monotonic lateral loads examines (i) the stress fields in reinforcement inside interior, exterior and roof exterior joints, and (ii) the load‐carrying capacity of representative sub‐frame models incorporating such joints. The results prove that it is actually safe, with respect to the joint load capacity, to base the design of longitudinal reinforcement in beams and columns on the internal force values at the joint periphery. This result also contributes to the recommendation to use real‐size beam‐column joint models in the analysis procedure.