Deflection Calculation Of Composite Beams With Web Openings And Linear Buckling Analysis Of Steel Circular Arches

This thesis is consists of two parts. The first part is about deflection calculation of steel-concrete composite beams with web openings. The second part is about linear buckling analysis of steel circular arches.After composite beam’s web being perforated, the rigidities of perforated section are weakened, the perforated segment develops vierendeel deformation which leads to deflection increase. The deflection of perforated segment is classified and analyzed in terms of generation mechanisms, the key problems are pointed out. The effective width of slab working in bending resistance of the integral section bb and the effective width of slab working in shear resistance bs are supposed to be equal to those of composite beam without web openings, the effective width of slab working in bending resistance of the top section of perforated segment be and the calculation span of perforated segment le are still to be determined. Perforated partial model is established by finite element soft to extract data of force and deflection, which is used to calculate be and le, impact parameters analysis and formulas fitting are finished. Observed the deformation features of perforated segment, shear rigidity and bending rigidity of vierendeel members are combined into equivalent shear rigidity of perforated section.According to the phenomenon of different sectional rigidities, a segmented beam element model with single opening is established to obtain the deflection calculation formulas under uniformly distributed load by solving equilibrium differential equations. Compared with finite element analysis results of single opening in fixed position, those formulas are accurate but some results are unsafe, the error is analyzed and revised subsequently. Then, whether those formulas are suitable in conditions of opening position change, multiple openings and concentrated load in mid-span is verified, and the additional mid-span deflection of multiple openings can be calculated by accumulating those of each single opening. By immediately adopting composite beam’s bending theory considering the influence of slipping, a fine deflection calculation theory of composite beams with single web opening under uniformly distributed load is provided. Some basic linear buckling problems of steel circular arches focusing on critical axial force are analyzed. Calculation models contain three-hinged arch, two-hinged arch and hingeless arch. Load conditions contain uniform confining pressure, horizontally uniformly distributed loading and uniform dead load. The formulas of maximum axial force coefficient are obtained by internal force linear analysis. Linear buckling loads under three load conditions are obtained by linear buckling numerical analysis, formulas of critical axial force coefficients are fitted. And the results of horizontally uniformly distributed loading and dead load are provided in the form of improvement coefficient compared to those of uniform confining pressure.