دانلود رایگان مقاله انگلیسی رفتار خمشی آزمایشی ستون های فولادی I-section باریک وب - الزویر 2018

abstract

Tapered steel members offer a better cross-section utilization along the member, which makes them an interesting and more economical alternative to prismatic ones. Yet, the design methodologies available do not provide a clear and sufficient guidance for the stability verification of such members. Alternatively, nowadays, the existing computer capacity and software programs provide an accessible and rapid means of reproducing the structural performance of members and systems, although they require beforehand validation to assure the plausibility of their predictions. For that, a full-scale experimental programme on nonuniform members was carried out, covering column, beam and beam-column tests. The test results are used to validate a numerical model commonly used for the assessment of stability design rules. In this paper, firstly, a global overview of the experimental tests is presented, which covers the test layout, member dimensions and the supplementary tests, essentially characterization of material properties, geometrical dimensions and imperfections, and residual stresses. The key results from each experiment are presented and discussed, they are further compared with numerical and analytical estimations of the member resistance. Finally, the experimental results provide physical validation of the design method proposed in Marques et al. (2012) for web-tapered columns.

6. Conclusions

In summary, this paper presented four full-scale experimental tests on the stability behaviour of linearly web-tapered steel columns and beam-column. The columns were tested under constant axial force aiming for the assessment of their in-plane flexural buckling resistance and one member was tested under bending and axial force. The material and geometrical properties of all members were characterized experimentally and detailed global results were reported. The test campaign also included residual stresses tests, where four specimens with different geometries were tested.

The member geometrical properties were chosen to vary from stocky cross-sections to columns with slender (class 4) cross-sections, and therefore, they provide a good basis for their use as reference tests for the calibration and validation of numerical models.

Moreover, it was demonstrated that the commonly adopted numerical model for stability of steel members, as described in [2,3] is adequate of reproducing the experimental results if the real geometrical, material properties and imperfections are considered, together with a correct representation of the boundary conditions. Therefore, as this numerical model is supported by the experimental tests presented in this paper, it can be recommended as a good basis future development in the area of stability design.

Finally, the experimental results provide additional physical validation of the design method proposed in [2] for web-tapered columns.