In this paper, the incremental stress-incremental strain relations of the Jones- Nelson-Morgan nonlinear composite materials model have been developed. The in- cremental formulas are used to analyze stress in the structure made of the nonlinear multimodulus materials und er the nonproportional loading.

This paper introduces an analysis method of three—dimensional nonlinear finite element of reinforced concrete structures which is under complex stress conditions. The analysis considers the concrete materials' nonlinear stress—strain relations, tensile cracking, compression crushing and strain—softening ect. .

At first,this paper decides the stress strain relations of steel and core concrete of concrete filled square steel tubes. In the core concrete's stress strain relations,the interaction of steel tube and core concrete is considered.

According to the practical stress and strain relations of concrete,the ultimate loads of circular section and rectangle section members under eccentric loads are calculated with nonlinear analysis method. A theoretical calculation method for a convert coefficient of the ultimate load by the influence of eccentric load is established.

Kotsovos and J. B.Newman and one way stress strain relations of concrete in concrete filled steel tubes. Three dimensional stress strain relations of concrete in concrete filled steel tubes is proved by an example analyzed by finite element program, and it can be used for three dimentional dual non linear analysis.

The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests.

In order to obtain the tensile stress-strain relations, a special fixture was used for the impact tensile specimen.

Furthermore, the axial stress-axial strain relations between laterally confined concrete under axial compression and multiaxial stress-strain relations for steel at constant high temperatures were studied.

This paper gives the stress-strain relations of the variational types on the basis of an assumption concerning the small deformation in the theory of elasto-plasticity.

According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relations, which are given by the increment theory of elastoplasticity.

In earthquake-resistant design, consideration must be given to the ductility of structures when subjected to seismic loading into the inelastic range. Research work in connection with this papar includes analysis of experimental results and development of a computer program for the calculation of the ductility factor of reinforced concrete flexural members. A new expression for the stress-strain relation was used in establishing the moment-curvature relations. Besides, in connection with displacement...

In earthquake-resistant design, consideration must be given to the ductility of structures when subjected to seismic loading into the inelastic range. Research work in connection with this papar includes analysis of experimental results and development of a computer program for the calculation of the ductility factor of reinforced concrete flexural members. A new expression for the stress-strain relation was used in establishing the moment-curvature relations. Besides, in connection with displacement calculation the actual length of plastic regions and the actual distributions of curvature therein were also studied.

Careful observations and analyses were made in connection with the rebound of the excavated pit and the settlement of the box foundation of a 9-11storeyed RC-framed hospital building to be erected on typical prehis-toric quarternary pluvial/fluvial soil deposits within the urban district ofBeijing. It was found that the amount of rebound due to the release of over-burdenpressure of 1.08kg/cm~2 was 1.24cm, which amounted to more than 50% of the to-tal settlement corresponding to the finished loading of 1.8kg/cm~2....

Careful observations and analyses were made in connection with the rebound of the excavated pit and the settlement of the box foundation of a 9-11storeyed RC-framed hospital building to be erected on typical prehis-toric quarternary pluvial/fluvial soil deposits within the urban district ofBeijing. It was found that the amount of rebound due to the release of over-burdenpressure of 1.08kg/cm~2 was 1.24cm, which amounted to more than 50% of the to-tal settlement corresponding to the finished loading of 1.8kg/cm~2. It seemedtherefore not appropriate to use the net pressure, which was 0.7kg/cm~2 in thiscase, in calculating the settlement of deeply embedded large foundations inlike soils. Although the general shape of the overall/laveraged load-settlement curvewas roughly a straight line, a further study on the stress-strain relation-ships of the soil layers at three different points beneath the foundation showeda definite trend of non-linearity and inhomogeneity that warranted a specialstudy. A plane sain finite element analysis was made accordingly to achieve atheoretical insight into the problem.The computer program was based on crossbeam structure model and conventional layered-sum settlement analysis method.However, three semi-empirical coefficients were introduced in order to take-care of the non-linear stress-strain relationships of the soils at different partsof the foundation.The calculated settlements thus obtained were very close tothose observed.

In current methods for the calculation of the moment-curvature hysteretic curve, there are two basic assumptions concerning concrete in compression:(a) Cracked concrete, when subjected to compression under reloading, works as if uncracked.(b) For concrete in compression zone a stress-strain relation for repeated axial compressive cyclic loading, is adopted instead of that for reversed loading.On the basis of the above assumptions, the calculated moment-curvature curve under large cracked deformation will...

In current methods for the calculation of the moment-curvature hysteretic curve, there are two basic assumptions concerning concrete in compression:(a) Cracked concrete, when subjected to compression under reloading, works as if uncracked.(b) For concrete in compression zone a stress-strain relation for repeated axial compressive cyclic loading, is adopted instead of that for reversed loading.On the basis of the above assumptions, the calculated moment-curvature curve under large cracked deformation will present a pinching point; however such a point does not exist at the corresponding position in the experimental curve. Owing to the influence of secondary moment, the calculated result for load-deflection curve errs more than that for moment-curvature curve. If we consider the local contact effects of cracked section during reloading, the pinching point will disappear from the calculated hysteretic loops.On the basis of test data of local contact effects of cracked section, we propose herein a new equivalent concrete stress-strain relation for reversed loading. With the use of this relation instead of that for repeated loading, good agreement between experimental and theoretical results of hysteretic loops can then be obtained.