Papers by Author: Hong Nan Li

Abstract: In the simulation of the rotational seismic ground motion, the apparent velocity of Love wave is always assumed to be equal to the S wave velocity of top layer of the site approximately, with the dispersion of surface wave not being fully considered. In this paper, the effect of the velocity structure to the Love wave dispersion is discussed based on the stiffness matrix theory. It shows that to assume the velocity to be equal to the S wave velocity of the top layer may greatly overestimate the low frequency rotational seismic motion. A simplified dispersion curve, is suggested for rotational seismic ground motion simulation. The shape of the bilinear curve is shaped by 3 parameters. They are the corner frequency, the minimum phase velocity and the velocity ratio. The parameters are affected by the velocity structure of the site.

Abstract: The prominent problems existing in construction domain of China are analyzed. Then the solutions are proposed to solve these problems. The decision-making at early stage of a project need to be paid high attention, and the key management systems need to be perfected and innovated. The interaction of regulatory authorities, the interaction between construction market and construction site, and between credit evaluation and bidding and tendering management, need to be realized. Dalian Construction Credit Information Web is developed and has the function of inquiry, monitoring and consultation service. The interaction among the abovementioned web, Digitalized Construction Site Management System and Bidding and Tendering Web is realized to share information and achieve the management of institutionalization, standardization, specialization and informatization for construction projects and market. The proposed solutions strengthen and normalize the monitoring of the construction market effectively and can provide reference for the construction project management in other area.

Abstract: Government-invested construction projects have their own characteristics, and effective management can be achieved only by adopting corresponding appropriate management approaches. The characteristics of government-invested construction project management and corresponding serious problems existed in present management are analyzed and summarized at first. Secondly, the countermeasures to above problems are put forward. Then, an information management system framework for government-invested project management is proposed on the basis of the foregoing work. This framework can realize the fusion of project information management system and E-government system and achieve the institutionalization, standardization, informatization and lifecycle management for government-invested project by means of multiple modernized information technologies and professional software. Finally, the development and application of the developed information system validate the effectiveness to promote the management level of government-invested construction project. The work involved in this paper can provide reference for the management of other similar construction projects.

Abstract: The Cup-type transmission tower-line system was a classic representative of high voltage electric power carrier, which was an important lifeline project. However, it frequently collapsed under different environmental loadings, especially strong wind. In this work, four tower five line finite element models simulated wind-induced progressive collapse process by birth-to-death element technique in ABAQUS/Explicit. The numerical simulation results demonstrated that this application could describe the structural collapse performance clearly and effectively and transmission tower-line system collapse path depended on the number, position and last deformation of damage elements.

Abstract: Considering transmission tower-line system coupling vibration ,construct a three dimensional finite element nonlinear analysis model for 500KV Shanghai to Xuzhou transmission line project.Execute Dynamic response analysis of transmission tower-line system under broken wire impact with SAP2000.The results show that :broken wire influence on the reaction of transmission tower-line system displacement and internal force can not be ignored ;influence on the reaction of transmission tower-line system displacement and internal force caused by ground wire broken is less while that of conductor is significant,peak value of a stem internal force can be as much as 2 times initial axial force ;the more wires are broken,the vibration response of transmission tower-line system is greater, the safety degree is lower;when it comes to internal force,there is significant difference between consider broken wire load as impact load and as static load,dynamic effects cannot be ignored.

Abstract: This paper presents a phase of the research program to determine the feasibility of a proposed CFRP retrofit method to strengthen the corroded concrete filled steel tube columns. This method is wrapping the corroded concrete filled steel tube column with CFRP material. Eight concrete filled steel tube columns were tested in the laboratory with four of them strengthened using the proposed technique. All specimens were notched in the center zone to simulate the loss of section due to corrosion the four of them were wrapped with CFRP composite tubes in the damage area. All specimens were axially loaded to failure while strain and displacement were measured to demonstrate the validity of this repair concept. This paper presents the experimental results and discusses the findings with preliminary conclusions on the feasibility of the proposed strengthening method.

Abstract: In order to investigate the compressive property of the concrete corroded by seawater in low-temperature, compressive tests are conducted on concrete specimen, which are corroded by accelerated corrosion method. Artificial seawater solution (Major ions concentration are five times of yellow seawater), are applied as the corrosive medium in the laboratory. Uniaxial compressive mechanical properties of the concrete tests, including 60 prism concrete specimens, are carried out. The physical and mechanical properties (including surface, mass, compressive strength, elastic modulus et al) of concrete in the different corrosion degree are researched. Taking the strength degradation ratio and elastic modulus loss as damage index, effects of the corrosion solution on the property of corroded concrete are discussed in detail. Relationships between the damage index and corrosion state of specimens are achieved.

Abstract: Corrosion ratio is an important index to study the mechanical deteriorates of the steel bars, which has a significant effect to evaluate the residual bearing capacity of reinforced concrete structures. To investigate the mechanical properties of the corroded steel bars, Strain energy loss as corrosion ratio is firstly proposed. Tensile test are conducted on ribbed and plain steels, which are corroded by acceleration corrosion method. Comparing with the weight loss and cross-section loss to describe the effect of corrosion of reinforcing bar, the strain energy loss of reinforcing bars is calculated by Simpson quadrature. Results from this paper and other researchers’ test suggest that the strain energy loss may be a better parameter than weight loss or section loss which to assess the corroded steel bars.

Abstract: A novel sensor placement criterion is proposed for structural health monitoring after five influencing criteria are critically reviewed. The objective of the proposed criterion is to achieve best identification of modal frequencies and mode shapes through almost unbiased estimation of modal coordinates. The proposed criterion derived by the Representative Least Squares method depends on both the characteristics and the actual loading situations of a structure. It selects sensor positions with the best subspace approximation of the vibration responses from the linear space spanned by the mode shapes. Furthermore, the connection between the Effective Independence and the approximate Representative Least Squares estimator is obtained through matrix perturbation analysis. It is found that the Effective Independence is a step-by-step approximation to that of the Representative Least Squares criterion.

Abstract: This paper investigates the lag time and the highest working frequency of Fiber Bragg Grating strain sensor in which strain wave transfers to bare FBG by analyzing the transmit course of the strain wave. The results show that the FBG strain sensor is applicable to the measurement of low frequency vibration in engineering. As its application, FBG strain sensors are used in the shake table test of offshore platform model and show good capability in measuring the dynamic strain of vibration system with low frequency.