Inference of Short-Term Maximum Crack Width of RC Flexural Members Based on Interval Estimation MethodYao, Jitao; Yan, Hanbing; Yan, Mingdong
doi: 10.1088/1757-899X/780/3/032001pmid: N/A
The design method based on observation and experimental model only considers the design of ultimate limit state in related research, the application range is not wide. This paper takes the short-term maximum crack width of RC flexural members as an example, puts forward the application of this method in the design of serviceability limit state. Dimensionless method was used to collect 4665 pieces of RC flexural member crack width data, and the normality test was performed to obtain the type of probability distribution obeyed by the crack width. Considering the situation without parameter information and known coefficient of variation, a direct estimation formula for short-term maximum crack width of RC flexural members based on interval estimation method is proposed.
Damage Detection Method of Ancient Timber Structure Based on BP Neural Network and Total Wavelet Energy RateHu, Weibing; Yang, Jia; Hou, Yanfang
doi: 10.1088/1757-899X/780/3/032002pmid: N/A
In order to detect the damage of beams and mortise joints of ancient buildings under environmental excitation, a damage identification method combining wavelet transform with improved BP neural network is proposed. The acceleration signal of the structure under the environment excitation is extracted and the total energy change rate of wavelet is obtained by wavelet discrete reconstruction, which is taken as the damage index. A finite element model of a timber frame of Xi’an bell tower is established to verify the proposed method. When the damage extent is less than 50%, 96% of the test samples in the neural network output the desired value; This method provides a theoretical basis for the study of damage prediction of timber structures in ancient buildings under environmental incentives.
Numerical investigation of ALSTON turbine generator foundations using different finite element modelXu, Li; Li, Hongbo; Gao, Xiaolong
doi: 10.1088/1757-899X/780/3/032004pmid: N/A
ALSTOM turbine generators have been used in the power plant all over the world. The previous turbine generator foundations were mainly designed and analyzed by the professional design software. In this paper, FE models using frame element in the finite element software of SAP2000 and solid elements in the finite element software of ABAQUS were built to simulate the ALSTOM turbine generator foundation, respectively. Model analysis and forced vibration analysis were conducted and the simulation results were validated against the existing codes and specifications provided by manufactory. The dynamic characteristics of the turbine generator foundation could meet the requirements of the applicable codes and standards. The FE models built with solid element could better simulate the dynamic characteristics of turbine generator foundations.
Flaw detection in concrete media using XFEM and an improved artificial fish swarm algorithmZhao, Wenhu; Du, Chengbin; Li, Xinzhu
doi: 10.1088/1757-899X/780/3/032005pmid: N/A
A novel strategy is proposed in this paper for identifying and characterizing the irregular flaws in heterogeneous media. The optimization iterations are implemented by using the improved AFS algorithm and the corresponding forward analyses are solved by XFEM. A series of candidate sub-defects are employed to describe each flaw jointly. Each candidate is devised as a square void with the boundaries matched the XFEM meshes to avoid subdividing the enriched elements. The K-means cluster algorithm is utilized to narrow the searching space and output the number of flaws. A typical numerical example is conducted to demonstrate the proposed strategy. The result indicates that this strategy can identify the irregular flaw and it is potential to be applied in the evaluation of the civil and hydraulic structures.
Comparative In-situ Test and Numerical Simulation on Underreamed Ground AnchorGuo, Gang; Xue, Zizhou; Hu, Xiaochen; Zhong, Guang; Liu, Zhong
doi: 10.1088/1757-899X/780/3/032006pmid: N/A
Underreamed ground anchor is an anchorage technology of safety and economy. Engineering companies worldwide developed various types of underreamed anchors with partially enlarged anchor body. In recent years, a kind of cylindrical underreamed ground anchor with geotextile bag is applied in China. Because of its corrosion resistant performance and high construction guarantee rate, the underreamed ground anchor with geotextile bag is widely recognized. In order to study its mechanical performance, a comparative in-situ test between the underreamed anchor and normal shaft anchor is held in China. Through the test, the advantages of bearing capacity and deformation performance are analyzed. Based on the test, the numerical model of cylindrical underreamed anchor is established, and the relationship between its capacity and the response of the surrounding soil is researched.
Measurement management of electronic instrumentsLuan, Yuanling; Zhang, Shisong; Zhang, Jianfei
doi: 10.1088/1757-899X/780/3/032007pmid: N/A
With the continuous development of science and technology, electronic instruments and meters measuring equipment in accuracy, accuracy and sensitivity has been rapid development, and widely used in scientific research and production in China. As a measuring tool, instrument measurement can detect, analyse and manage products, effectively improve product quality in product production supervision and inspection, effectively reduce resource waste, and protect the legitimate rights and interests of users. Although the accuracy of electronic instruments is required more and more, due to poor management, there are often various problems in the use process. In this paper, combined with the extensive needs of electronic instruments in the new situation, the current development status of electronic instruments in China is analysed, and relevant improvement measures are put forward for the problems, aiming to strengthen the measurement management of electronic instruments and ensure the smooth progress of scientific research and production.
Discussion on Application of BIM Technology in Aluminum Alloy Formwork Support SystemLongbo, Zhang
doi: 10.1088/1757-899X/780/3/032008pmid: N/A
With the development of science and technology, society has put forward more stringent requirements for the construction industry. The traditional two-dimensional design method can no longer meet the requirements of architectural design. The proposal of BIM technology and its application in the construction industry have solved the problems existing in traditional architectural design methods and adapted to the long-term development needs of architectural design. In the design of aluminum alloy formwork support system, BIM technology can realize efficient processing and management of massive data, realize informationization and integrated management of project design, and effectively improve the quality of project design. In view of this, the author believes that it is necessary to analyze the application of BIM technology in the design of aluminum alloy template support system. Based on the overview of this new technology, this paper will analyze and discuss the application and practical application of BIM technology in the design of aluminum alloy template support system.
Numerical Simulation on Dynamic Response of Prestressed Concrete Slab Subjected to Blast LoadingBai, Chongxi
doi: 10.1088/1757-899X/780/3/032009pmid: N/A
In order to obtain the dynamic response of prestressed concrete slab subjected to blast loading, the numerical modeling method for the dynamic response analysis of this kind of member subjected to blast loading was introduced, and the numerical model was established based on the ANSYS/LS-DYNA program. By comparing the numerical simulation results of the dynamic response of reinforced concrete slab with the experimental data subjected to blast loading, the accuracy of the numerical model was verified. So the numerical simulation method can be used in dynamic response analysis of prestressed concrete flexural members subjected to blast loading, with a certain precision.
Study on Artificial Boundary of Saturated Soil Medium Viscoelastic Dynamic Based on Biot Dynamic Consolidation EquationsYu, Jun; He, Yue; Zhao, Shuang; Li, Zhen
doi: 10.1088/1757-899X/780/3/032010pmid: N/A
Based on modification of Biot dynamic consolidation equation, the equations in saturated soil plane normal, out-of-plane tangential and the tangential plane are calculated by method of separation of variables and operator decomposition, analytical solutions of the displacement of the saturated soil skeleton and the pore are obtained under the corresponding conditions. Then the physical equations of Biot saturated porous media are expressed in two parts by combined use of geometric equations, the three-dimensional artificial boundary of saturated soil considering energy dissipation and transformation is established. Finally, numerical examples of classic wave motion problems demonstrate that high precision is achieved by use of three-dimensional visco-elastic boundaries, and that the boundaries can be used in analysis of three-dimensional wave motion problems easily.