Inelastic stability of diagonal braces in building frames | |
| Author | Supachai Limpisvasti |
| Call Number | AIT Diss. no.D18 |
| Subject(s) | Elastic plates and shells Elasticity Framing (Building) |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering of the Asian Institute of Technology, Bangkok, Thailand |
| Publisher | Asian Institute of Technology |
| Abstract | The elastic-plastic behavior of diagonal braces in building frames, which are rigidly connected to relatively rigid beams and columns and subjected to relative horizontal displacement induced by horizontal loads, is investigated both theoretically and experimentally with particular reference to the post-buckling behavior. The analysis is based on commonly adopted piecewise linear approximate moment-thrust interaction curves and bilinear elastic-plastic moment-curvature relations. Thus the differential equation governing the elastic bending of compression member is applicable to the entire domain of the brace in the elastic, elastic-plastic and mechanism states with the formation of plastic hinges which mark the transition between consecutive states and divide the brace into separate domains. The results of the theoretical investigation show that, depending on the slenderness ratio, diagonal braces exhibit three distinct characteristics. For short braces the horizontal load-displacement relations are stable in the elastic and elastic-plastic states, which terminates by axial yielding at incipient plastic collapse. In the medium slenderness ratio range, the braces attain the maximum loads at the termination of the elastic-plastic state for a narrow lower medium range, but at the termination of the elastic state for the upper medium range. In both cases, the stable branches of the horizontal load-displacement curves are followed by a steep unloading branch, with initially positive slope which becomes infinite at a point beyond which the curves become unstable. Finally, long braces behave elastically until the maximum loads are attained at the termination of the elastic state, and the un¬loading branches of the horizontal load-displacement curves, which characterize the elastic-plastic and mechanism states, are unstable. The maximum loads as well as the horizontal load-displacement curves observed in the experimental investigation agree well with the theoretical prediction for short braces. In the medium range, however, the maximum experimental loads are smaller than the theoretical predictions and occur consistently in the vicinity of the point of infinite slope in the theoretical horizontal load-displacement curves. The experimental curves start to deviate from the theoretical curves shortly before reaching and snap through at this point, showing rapid increase in the displacement. For practical purposes, a simple means for predicting the maximum loads in this range is recommended in view of these findings. |
| Year | 1976 |
| Type | Dissertation |
| School | AIT Publication (Year <=1978) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Dissertation (D) (Year <=1978) |
| Chairperson(s) | Morino, Shosuke; |
| Examination Committee(s) | Lee, Seng-Lip; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1976 |