Structural Efficiency of Hollow Reinforced Concrete Beams Subjected to Partial Uniformly Distributed Loading

Abstract

Reinforced concrete (RC) beams containing a longitudinal cavity have become an innovative development and advantage for economic purposes of light-weight members without largely affecting their resistance against the applied loads. This type of openings can also be used for maintenance purposes and usage space of communication lines, pipelines, etc. RC beams are primarily loaded in the plane of the members, which are two-dimensional in a plane stress state and the dominant structural behaviours include bending, shear, or combination of both. In the present study, six numerical models of RC beams with and without openings were simulated by using commercial finite element software ANSYS to evaluate the structural behaviours of those beam models under the partial uniformly distributed load. Different parameters were assessed, including opening dimensions and shear reinforcement ratios. The obtained numerical results were analysed and verified and were found very close to those obtained from the experimental investigations in the literature. The increase of shear reinforcement ratio could enhance the flexural and shear capacities of the RC beams, and the results also showed that some models sustained flexural failure while the others sustained failure of combined bending and shear.

Numerical Simulations on the Flexural Behaviours of Reinforced Concrete Girders Strengthened with Bolts

“…These stresses were generally concentrated diagonally at the points of the applied loads and supports, as well as around Also, these stresses were higher for the models with openings because they caused less rigidity by 8-15% in comparison with others under the same applied loads. It can also be noted that the increase in the concrete compressive strength could decrease the stress concentration by 18-26% [21,22]. For the strengthened models with bolts, they could provide a higher rigidity to the models in comparison to the unstrengthened ones [39] and reduce the stresses by 23-31%.…”

“…Also, several influencing factors have been explored, e.g., sizes and locations of openings, flexural and shear reinforcement ratios, and strengthening of hollow beams with various ways. Many studies have assessed the performances of RC beams with various positions of cavities, e.g., longitudinal openings [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Meanwhile, other studies have investigated the performances of RC beams with openings in webs [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

“…The reinforcing steel bars of various diameters, as well as the strengthening bolt rods, were represented by the connecting element link 180, which contained two nodes with three degrees of freedom at each node. For the steel plates placed at the supports and loading points, the element solid 185 was used, which had eight nodes with three degrees of freedom at each node [19,21,22].…”

“…The coefficients of open and closed concrete cracks were defined as 0.2 and 0.7, respectively. The stress-strain relationships for all materials were assumed to be completely elasticperfectly plastic [21,22]. The components of the stress-strain curves of concrete were formulated and defined during the simulation by the ANSYS program [38].…”

“…The basic hypothesis considered that the relationship was linear up to 0.85f c , and then became plastic to the concrete strain of 0.003. Also, the self-weights of the models were neglected and considered as homogeneous with a complete full bond between all parts [21,22]. Figures 9 and 10 show the basic steps of numerical modelling by the software ANSYS [38], which included the dimensions of the RC girder models, three-dimensional models, reinforcing rebars, openings (transverse holes), strengthening bolts, steel plates under the loading, and supports.…”