BRI Research Paper


An Evaluation Method for Shear and Flexural Deformations of Shear Walls.

H.Hiraishi*1; May, 1985. 28p.


In order to predict the history of inelastic response of R/C structures under dynamic earthquake loading, hysteretic behavior must be known for each sismic member, i.e., beams, columns and shear walls.Hysteretic behavior of beams and columns has been made clear through many experimental and analytical studies and some hysteretic load (moment)versus deformation (curvate) models, such as the Takeda model (which shows good agreement with experimenta.l results of flexural members), have already been proposed.

Stresses and deformation of shear walls before cracking are obtained from two-dimensional analysis1),2)and able to be approximately predicted by elementary bending theory. The flexural cracking strength, maximum flexural strengths, the deformation at maximum strength, and the reduction factor for shear rigidity of shear walls (where shear deformation is dominate) have been made clear quantitatively3),4). However, there are many uncertainties regarding the behavior of shear walls after cracking. And a practical hysteretic load versus deformation niodol has not yet been proposed.

The Difficulty in modeling of the load versus deformation relation of shear walls is mainly due to the difficulty in the prediction of not only strengths but also deformations. For example, the effects of shear cracks and yielding of reinforcing bars on flexural rigidity and shear rigidity, respectively, has not clarified yet.

Many experimental studies on shear walls have been carried out,and most of their load-deformation data are presented in terms of the load versus total deformation. A very few data refer to the shear and flexural deformations primarily because of the difficulty in distributing the total deformation into the flexural and shear deformations. This distribution,however, is useful to investigate inelastic behavior, particularly for flexural failure type shear walls since in these walls shear deformation as well as flexural deformation tremendosly increases after occuring of cracks of concrete and yielding of reinforcing bars.

This paper reports on an evaluation method of distributing the total deformation of a shaer wall into the flexural and shear deformations.For this evaluation, rotation of the shear wall at the mid-height of a story is used in addition to the horizontal and vertical displacements at four corners of the shear wall. The paper also discusses the accuracy of this method based on analytical results of shear walls.

This method of distribution is available to any member whose defor-mation contains flexural deformation and shear deformation. However,the "shear wall" is used in this paper because shear deformation is usually more noticeable in shear walls than in other structural members.

*1 Senier Research Engineer, Structure Division, Structural Engineering Department

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