In order to study the calculation methods of bending behavior of Chinese reinforced concrete beams from 1912 to 1949, tests on the mechanical performance of 66 rebars from different modem Chinese concrete buildings, t...In order to study the calculation methods of bending behavior of Chinese reinforced concrete beams from 1912 to 1949, tests on the mechanical performance of 66 rebars from different modem Chinese concrete buildings, the concrete compressive strength of 12 modem Chinese concrete buildings, and the concrete cover thickness of 9 modem Chinese concrete buildings are carried out; and the actual material properties and structural conformations of modem Chinese concrete buildings are obtained. Then, the comparison on calculation methods of bending behavior including the original Chinese calculation method, the present Chinese calculation method, the present American calculation method and the present European calculation method is studied. The results show that the original Chinese calculation method of bending behavior is based on the allowable stress calculation method, and the design safety factors are 3.55 to 4. 0. In term of the calculation area of longitudinal rebars of reinforced concrete beams, without considering earthquake action, the original Chinese structural calculation method is safer than the present Chinese structural calculation method, the present European structural calculation method, and the present American structural calculation method. The results can provide support for the structural safety assessments of modem Chinese reinforced concrete buildings.展开更多
This paper focuses on the results of experimental work on workability and compressive strength of self-compacting concrete （SCC）. The work concentrated on concrete mixes having water/binder ratios of 0.45 and 0.35, ...This paper focuses on the results of experimental work on workability and compressive strength of self-compacting concrete （SCC）. The work concentrated on concrete mixes having water/binder ratios of 0.45 and 0.35, which contained constant total binder contents of 400 kg/m^3 and 500 kg/m^3, respectively. Based on the experimental results, the existing suggestions for anticipating the long-term compressive strength of SCC according to its compressive strength at the age of 7 days were not exact enough. Therefore, it is decided to use artificial neural networks （ANN） for predicting the long-term compressive strength of SCC from its workability and short-term compressive strength. For predicting the long-term compressive strength of SCC utilizing ANN, multi layer perceptron （MLP） networks and radial basis function （RBF） networks were chosen. The conclusion was that the MLP networks could properly predict the long-term compressive strength in all conditions, but RBF networks were not exact enough in some circumstances. On the other hand, RBF networks were more users friendly and they converged to the final networks quicker.展开更多
基金The National Natural Science Foundation of China(No.51138002)the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(No.201452)the Open Fund of Shanghai Key Laboratory of Engineering Structure Safety(No.2015-KF06)
文摘In order to study the calculation methods of bending behavior of Chinese reinforced concrete beams from 1912 to 1949, tests on the mechanical performance of 66 rebars from different modem Chinese concrete buildings, the concrete compressive strength of 12 modem Chinese concrete buildings, and the concrete cover thickness of 9 modem Chinese concrete buildings are carried out; and the actual material properties and structural conformations of modem Chinese concrete buildings are obtained. Then, the comparison on calculation methods of bending behavior including the original Chinese calculation method, the present Chinese calculation method, the present American calculation method and the present European calculation method is studied. The results show that the original Chinese calculation method of bending behavior is based on the allowable stress calculation method, and the design safety factors are 3.55 to 4. 0. In term of the calculation area of longitudinal rebars of reinforced concrete beams, without considering earthquake action, the original Chinese structural calculation method is safer than the present Chinese structural calculation method, the present European structural calculation method, and the present American structural calculation method. The results can provide support for the structural safety assessments of modem Chinese reinforced concrete buildings.
文摘This paper focuses on the results of experimental work on workability and compressive strength of self-compacting concrete （SCC）. The work concentrated on concrete mixes having water/binder ratios of 0.45 and 0.35, which contained constant total binder contents of 400 kg/m^3 and 500 kg/m^3, respectively. Based on the experimental results, the existing suggestions for anticipating the long-term compressive strength of SCC according to its compressive strength at the age of 7 days were not exact enough. Therefore, it is decided to use artificial neural networks （ANN） for predicting the long-term compressive strength of SCC from its workability and short-term compressive strength. For predicting the long-term compressive strength of SCC utilizing ANN, multi layer perceptron （MLP） networks and radial basis function （RBF） networks were chosen. The conclusion was that the MLP networks could properly predict the long-term compressive strength in all conditions, but RBF networks were not exact enough in some circumstances. On the other hand, RBF networks were more users friendly and they converged to the final networks quicker.
