A linearization method of the uniaxial non-fitting nonlinear stress-strain curve given by the author of the paper is presented. The evolution equation between disturbances variable and plastic strain is derived based on Theory of Duality Disturbance. A simple method for concrete structures preforming elastoplastic analysis is presented (including softening analysis).

A fine analysis model for joints in axial shear is given on the base of observation of experiment. Failure of the pin connecting adherends is due to combined deformation of pressure-shear. Both critical region of the pin and the stress state in critical rejoin are evaluated. Ultimate load Fu of the joint in axial shear is evaluated with strength criteria. The following conclusions are obtained. (1) Fu is related to ratio of adherend thickness t to length L. Fu increases with t when t/L is less than 0.1 and hold as a constant when t/L is greater than 0.2; (2) Fu can well be predicted by bi-shear theory or maximum tension strain criterion, but not by Tresca and Mises criteria; (3) Although traditional approximate calculation method of connections is widely used, related experiment must be done for obtaining ultimate shearing stress. Thus, the fine analysis method presented in this paper is useful for stress analysis and strength evaluation of connections.

An approach to increasing the loading ability of adhesive joints by adding reinforced pins is presented. Following procedures are taken for making adhesive joints with reinforced pins: At first, holes are drilled at the overlap region of adherends, and then one hole is filled with a metal pin and adhesive. At the same time, adhesive is also applied on the surfaces of the overlap of adherends. After cured, the metal pin and the adhesive in one hole form an adhesive-metal reinforced pin. In this study, strengths of single-lap adhesive joints with the reinforced pins were measured experimentally. It is found that to well-bonded joints, (1) the strength of single-lap adhesive joints with adhesive-metal pins are obviously greater than those without adhesive-metal pins; (2) the strength of single-lap adhesive joints with adhesive-metal pins is highest when the pins are located at the positions of 5mm from the two ends of the overlap segment, the strength of single-lap adhesive joints with adhesive-metal pins is lowest when the pins are located at the middle of the overlap segment, about 10mm from the two ends of the overlap segment.

Drilling-Hole-Loading method is applied to predicting and measuring the tensile strength of irregular small-size stones. According to this method, a circular-hole must be drilled at the center of the irregular small-size stone. The mechanical model of the stone with a circular-hole and subjected to a pair of equivalent collinear pull forces is set up. The normal stress strain distributions on the critical section are anlyzed. Theoretical stress concentrated factor equation related to the hole diameter is calculated. Based on the static equilibrium theory, the theoretical formula of predicting the tensile strength of irregular small-size stones is established. Based on the theoretical formula, the test device for measurement of the tensile strength of the stone was designed. The tensile strength of a kind of bluestone was measured. The results show that the tensile strength predicted by Drilling-Hole-Loading method is a little lower than that of the standard specimen of stone without hole. Drilling-Hole-Loading method can be used to predict the tensile strength of brittle material and irregular small-size stones.