Advanced Materials Research Vols. 163-167

Abstract: Three contents are included in this paper: 1) Through orthogonal experiment, some principal materials and their use levels which will influence performances of cement formwork are optimized and researched. A matched group could bring best comprehensive performance plate suitable to be used as construction formwork is obtained. 2) Through study the strength retention rate of specimens after immersing in various solutions for different ages, the alkali resistance property and lasting quality of the formwork are investigated, and it indicates that during general serviceable life specified by China Structure Design Code, the failure probability due to durability is very low. 3) Through mechanical experiments of combined slabs with different conjoint methods, cooperation performance between formwork and concrete is studied, which prove composite slabs work well.

Abstract: Four types of recycled concrete specimens were made for dynamic loading tests in laboratory, in order to research the ultrasonic propagation characteristics and damage evolution of recycled concrete under dynamic loading. Ultrasonic propagation parameters such as ultrasonic propagation wave time, ultrasonic velocity and ultrasonic amplitude of recycled concrete were tested synchronously while recycled concrete were loaded. Tests results show that ultrasonic propagation wave time increased with the rise of cyclic times, while ultrasonic amplitude decreased in the same time. Damage variable evolution of recycled concrete lived through obvious three stages during the loading process. The development of inner cracks of recycled concrete in loading process accordingly were the stage of the growing of original cracks, the stage of the expansion of cracks and the stage of the linkage of cracks.

Abstract: Bear Angle Vertical Swivel Method for arch bridge has been developed for many years overseas and obtained stated success such as Kobaru Valley Bridge in Japan and ArgenLobel bridge in Germany, this method is in the researching period right now in China. During the processing of construction, concrete of arch rib was casted vertically and then rotated, main arch ring was casted vertically by formwork climbing technology, main arch ring was laid to completed bridge elevation by using continues jacks, forming a set of swivel construction method for arch bridge.

Abstract: Regarding foundation of large concrete equipment construction in winter as an example, This paper solves a problem that is the conflict between the external thermal insulation in winter and internal commonage in mass concrete cracks controlling. Through the theories according to the specific circumstances of the construction, control objectives and control methods are laid down from various aspects of the construction structure and materials. Foundation of the large concrete equipment cracks is controlled successfully in winter.

Abstract: This paper presents an experimental study of shear behavior of simply supported HSC beams reinforced with high-strength stirrups under monotonic concentrated loading. Six specimens with 150×300 mm square cross section were tested. The effects of three variables such as the stirrup ratio, stirrup yield strength and average confining stress are studied. Based on test results, the shear behavior of HSC beams with high-strength stirrups was evaluated. Combined with other test results, shear strength measured in test are compared with the values calculated according to the expressions proposed in this paper and in Code for design of concrete structures of China (GB 50010-2002). The study concludes that shear capacity is sparingly estimated by the Code for design of concrete structures of China (GB 50010-2002) when the average confining stress below 3MPa, but it is emphasis on insecurity when the average confining stress exceeds 3MPa. The empirical equation proposed in this paper for predicting the shear strength of HSC beams with high-strength stirrups is appropriate.

Abstract: The models to calculate the effective bond length determined by single-lap or double-lap shear tests are more suitable for the end-debonding failure; and the improved models based on the simply shear test models to calculate the effective bond length of flexural CFRP-strengthened beams failed by intermediate crack debonding (IC debonding) are also lack of the support of experimental data. To investigate the effective bond length of flexural CFRP-strengthened beams, a total of 9 flexurally CFRP-strengthened beams were tested. The experimental results show that the existing models are very conservative for calculating the effective bond length in flexural FRP-strengthened RC beams failed by IC debonding. Based on the experimental results, this paper presents a model to calculate the effective bond length of flexural FRP-strengthened RC beams failed by IC debonding, and a model to calculate the plastic hinge length at the shear-flexure span.

Abstract: This paper presents the nonlinear dynamic simulation analysis of a shaking table test specimen, which was a twelve- story reinforced concrete frame and tested under base excitations representing four earthquake records of increasing intensity. Owing to the length constraint of the paper, three cases are used for the simulation. The numerical simulation of the test model is conducted utilizing the finite element analysis procedure CANNY, and the analysis results include the natural frequency, response history of the frame and the damage evolution. It is concluded from comparisons between experimental results and the numerical simulation ones that the latter matches well with the former, therefore the validity of the analytical method and model for simulation of RC frame shaking table test is proved.

Abstract: The feature of the concrete grid-frame structure with specially shaped columns is the frame beams and specially shaped columns in the walls were divided by rib beams and rib columns, then the rib beams, the rib columns, the frame beams and the specially shaped columns together constitute the grid-frame structures with specially shaped columns. The rib beams and the rib columns can share parts of the vertical and horizontal loads which the structure should bear and work together with the frame beams and the specially shaped columns, so make the lateral stiffness of the structure is increased and the ultimate strength, ductility and seismic performance of the structure are improved. Moreover, Phosphorus gypsum will be poured to enclose concrete beams and columns and become the filler wall among them. At the same time, phosphorus gypsum wallboards are used as the middle filler walls to separated rooms flexibly. By doing so, the building is more energy saving. In addition, the phosphorus gypsum which is a type of industrial waste can be consumed and become useful material in construction.

Abstract: Based on influencing factors of the diagonal crack widths of high-strength reinforced concrete beam, the paper presents a model for predict the diagonal crack width of high-strength reinforced concrete beam by artificial neural network. The model is verified using experimental data; it indicates that the neural network model has a good effect on the forecast of the diagonal crack widths. At the same time, artificial neural network provides a new way to calculate the diagonal crack widths.

Abstract: In order to study the mechanical behavior on concrete continuous beams strengthened with CFRP sheets, three two-span continuous beams strengthened with CFRP sheets in the control section at each span were fabricated and tested with two-point loading type. The test data such as load, crack distribution and deformation were obtained in different stages. Based on the test data, the finite element analysis on the continuous beams strengthened with CFRP sheets was carried out by ANSYS software. The variation of steel stress and deflection of control section in the intermediate support and the bearing capacity in different stages were obtained, moreover, the results show that the ultimate strength of continuous beams strengthened with CFRP sheets has not improved largely in elastic state while increased significantly in plastic state, and the continuous beams displayed obviously internal force redistribution.