Comparative Study On Domestic And Overseas Design Theories And Methods Of Concrete Structures

The Code for Design of Concrete Structures of our country have been entirely revised three times since its origin was published in the 1960s, however, compared with other advanced codes and specifications, the calculation method in the Code of our country is unique, and mainly depends on formulas; moreover, in some part of the Code, the calculation formulas are empirical and based on the statistics of extensive experiment samples without systematic deduce of mechanics; furthermore, there are still some deficiencies in the Code. Therefore, referring to some advanced codes in the West, such as EC2 and ACI Building Code, this thesis provided advice and alternative design methods for our Code.A great part of this thesis focused on the strain-based "unified method" of design for flexure for reinforced concrete members, which is widely used and incorporated in most codes of west countries. In this thesis, a new "unified method" was deduced accord with the basic assumptions of our Code, the deduce detailing and calculating graphs and tables was provided also. This "unified method" has a number of advantages, because its formulas and calculations are simple, and its graphs or tables are brief and versatile, and its results are more accurate, etc. It including a series of dimensionless graphic or tabulation approaches, including: (1) three approaches for rectangular sectional members, namely the Dimensionless Graphic Approach, the Dimensionless Tabulation Approach and the k_h0 Approach; (2)one approach for T-sectional members, namely the Dimensionless Tabulation Approach; (3) two approaches for columns, namely the Dimensionless Graphic Approach and the Considering Second-order Dimensionless Graphic Approach. Among this approaches, take the Dimensionless Tabulation Approach ofT-sectional members for example, it is unnecessary to determine whether the neutral axis is in or out of the flange region, and it can be used for reinforcement calculation of members with T-shape or rectangular section, for simply or doubly reinforced members, for bending-compressive or bending-tensile members, and for members with material combination of ordinary concrete and steel bars. And the Considering Second-order Dimensionless Graphic Approach can be used for symmetrically reinforced columns, it is unnecessary to determine whether the column is small-eccentric or large-eccentric, and the second-order was considered in the graphs, so its calculation is very simple, and there are many other results available, such as strain of the reinforcements and the outer edge of concrete.At last, this thesis introduced the truss model to explain the performance and mechanics of members under shear or torsion, the formulas deduced by this model make sense, and are consistent to the empirical ones given in the Code, which are mainly gained by statistics, so the truss model can be taken as the theoretic model for shear and torsion designing.