Ultimate Strength Calculation And Analysis Of Stiffened Plate

Stiffened steel plate is the basic strength member in ship and offshore structures. Due to their simplicity in fabrication and excellent strength to weight ratio, stiffened steel plate are also widely used for construction of land-based structures such as box girder and plate girder bridges. Since the overall failure of a ship hull is normally governed by buckling and plastic collapse of the deck, bottom or sometimes the side shell stiffened panels, it is of crucial importance to accurately calculate the ultimate strength of stiffened panels in deck, bottom and side shell for more advanced structure design of ship structures.This paper used along Paik's calculation method of the ultimate strength of stiffened plate, develops advanced, yet design-oriented ultimate strength expressions for stiffened plate to combined axial load, in-plane bending and lateral pressure. The collapse patterns of a stiffened plate are classified into six groups (including overall buckling collapse, yielding along plate-stiffener intersection, column or beam-column type collapse, tripping of stiffeners, local buckling of stiffened web and gross yielding). It is considered that the collapse of the stiffened plate occurs at the lowest value among the various ultimate loads calculated for each of the collapse patterns. The stiffened plate ultimate strengths for all potential collapse modes are calculated separately, and are then compared to find the minimum value, which is then taken to correspond to the real stiffened plate ultimate strength.In the analysis of the two kinds of collapse of overall bucking and yielding along plate-stiffener intersection, according to larger deflection theory, control differential equation non-linearly and some appropriate hypothesis, ultimate strength calculate formula is found. To the column or beam-column type collapse, adopt the classical Euler's stress formula and Hughes formula to calculate out the value of ultimate strength. For local buckling of stiffened web, is it derive formula and Paik that appear through approximate calculation formula that test put out through analytic method to adopt; For tripping of stiffeners, use M. Ma formula asks out the ultimate strengthvalue. The post-weld initial imperfections (initial deflection and residual stress) are included in the developed panel ultimate strength formulations as parameters of influence.In a summary, a simple method of determining the ultimate strength of stiffened plate under in plate compressive loads is developed by analyzing and discussing the modes of failure. Finally, a program system is developed in FORTRAN language by using this simplified method to analyses the buckling of stiffened plate. In comparison with the results from famous experts of International Ship & Offshore Structures Congress. This simplified method has engineering accuracy and can be used in the stiffened plate of design.