Studies On Stability And Design Of I-sectional Arches With Web Openings

As a new structural member, the arch with web openings combines the featuresof both arches and members with web openings. In this study, the stability behaviorsof arches with and without web openings are investigated systematically by finiteelement method. The effects of openings on arches are favorably solved withappropriate equivalence. As a summary, ultimate strength design method of both solidweb arches and open web arches are proposed.Firstly, elastic buckling of circular arches are studied without displacementassumptions and the defect of classic theory is proved. The effects of openings onelastic buckling modes and loads of arches with web openings are studied. A newoptimization criterion based on a modified dimensionless elastic buckling load isestablished to evaluate the efficiency of arches with web openings. It is proved thatthe efficiency of members is improved with the introduction of openings and optimalsize of openings is given based on the criterion. The arch with web openings isrecommended to be analyzed as a battened two-T-section member based onslenderness equivalence.Secondly, the geometrical nonlinear equilibrium path and deformation process ofarches without web openings are traced and the elastic ultimate load is defined. Thegeometrical nonlinear behavior of arches with web openings is studied to show theamplified shear effect. Based on finite element results, deformation formulas areproposed for arches with and without web openings.Thirdly, the nonlinear buckling behavior and failure mechanism of arches areillustrated by analyzing the elastic-plastic buckling with different rise-to-span ratiosand slenderness ratios. Arches with web openings are also studied to fully understandthe effects of openings. A special failure mechanism of arches with web openings isdeclared compared with common arches. Local buckling also affects the nonlinearbuckling due to different parameters.Finally, an ultimate strength design method for arches is proposed to append tocurrent code for design of steel structures. A normalized slenderness ratio of arches isdefined and the relation between an arch's stability coefficient and its normalizedslenderness ratio is established in the form of Perry-Robertson formula. For archeswith web openings, an ultimate strength design method is also proposed with properequivalence. The design recommendations on arches with web openings aresummarized, including strength, stiffness, deformation, overall stability and localstability.