Papers by Author: Xiu Li Du

Paper TitlePage

Authors: Shi Wei Hou, Yi Fang Zhang, Jin Hong Qu, Xiu Li Du
Abstract: Damp Newton algorithm based on FEPG system is developed for calculating strain softening problem. The algorithm can solve displacement and yield surface equation simultaneously. Soften modulus is introduced into D-P yield function. The example result shows that, the algorithm with damp factor can be used to solve softening problems. The plastic theory described by finite element weak form has no requirement of continuity, so appropriate outcome can be obtained by first-order element. Descent segment of stress-strain curve and cloud picture of finite shear band are presented.
Authors: Zhen Hua Dong, Qiang Han, Xiu Li Du, Pi Guang Wang
Abstract: To investigate the seismic performance of FRP strengthened RC hollow section bridge piers under multi-dimensional earthquake excitation, the pseudo-static test was carried out to RC rectangular hollow section as-built and CFRP confined bridge piers under constant axial compression force and bidirectional horizontal repeated load. The failure characteristics, lateral force-deformation curves and ductility of specimens were analyzed. The experimental result shows that CFRP constraining may change the failure mode of hollow section bridge piers, and significantly improve the deformation ductility, plastic deformation, however, it is less contribution to horizontal force of specimens with less wall-thickness.
Authors: Xiu Li Du, Zuo Hu Wang, Jing Bo Liu
Abstract: Fiber reinforced polymer (FRP), particularly those incorporating carbon fiber (CFRP), has high strength, high stiffness-to-weight ratio and high resistance to corrosion, which shows potential for use as prestressing tendons in corrosive environment. However, concrete beams prestressed with FRP tendons have showed brittle flexural failure due to the elastic rupture of FRP tendons. In order to improve the ductility, a combination of bonded and/or unbonded prestressing tendons was used. Nine prestressed concrete beams were tested up to failure to study the effect of bonded and unbonded FRP tendons on their flexural capacity. Three factors were taken into consideration; the bonding condition of CFRP tendons, the location of CFRP tendons and the prestressing ratio. Also an analytical investigation was carried out to extend some flexural capacity calculation equations to this beam type. The results of the experimental showed that under the same condition, the carrying capacity of concrete beam prestressed with bonded FRP tendons was 20% higher than that of internal unbonded prestressed beam, and was 40% higher than that of external unbonded prestressed beam without deviators. By combination of bonded and unbonded FRP tendons, the ductility of prestressed concrete beams can be improved.
Authors: Xin Zhang, Xiu Li Du
Abstract: Frequency modulation procedure is proposed to overcome the mode-mixing problem associated with the EMD method when processing signals with closely spaced frequencies. This procedure also provides the flexibility to start the realization of IMFs either from the high frequency end as does the original EMD or from the low frequency end when the signal contains unwanted high frequency components. The EMD procedure, under the circumstances, may behave as high pass, low pass or band pass/stop filters. The proposed method, assisted by the Hilbert-Huang transform on the governing equations, identifies the instantaneous stiffness and damping coefficients as functions of vibration amplitude of a nonlinear system. The effectiveness of the proposed method is verified by numerical simulation.
Authors: Jia Song, Zhen Bao Li, Yong Ping Xie, Xiu Li Du, Yue Gao
Abstract: An experimental study was made of the mechanical properties of large scale confined concrete subjected to the axial compression test. Eleven tied concrete columns and six plain concrete prisms were tested. In the test, each specimen had the same transverse reinforcement configuration, and similar volumetric ratio of lateral steel, while different size. The test results in this paper indicate that the size of the specimen has no obvious relationship with the ultimate strength, however, it does affect the post-peak ductility to some extent. As a supplement to the experimental study, a finite element method was adopted to imitate the mechanical behavior of the confined concrete under axial compression. The results of the imitation in this paper indicate the confinement mechanism of large scale specimens.
Authors: Er Wei Guo, Zhen Bao Li, Hua Ma, Hong Yu Zhou, Xiu Li Du, Guo Hui Luo
Abstract: In order to research on seismic performance of full-scale beam-column joints of RC frames under low cyclic loading, finite element software ABAQUS is used to nonlinear analysis. Analysis results show that: the process of load carrying and fracture development of beam-column joints are simulated using concrete damage plasticity model; nonlinear finite element method is easy to obtain stress-strain relationship; and can effective analyses the complex mechanical behavior of core areas of joints.
Authors: Xin Zhang, Xiu Li Du
Abstract: A modal test was carried out on a 120m span concrete filled steel tubular arch bridge under operational conditions. The moving traffic load is considered as uncorrelated white noises at various points of the road surface and the test is of the type of multi-input multi-output (MIMO). The modal parameters are identified by Global Rational Fraction Polynomials (GRFP) method, a frequency domain method. In order to taking the mobile nature of the traffic load into consideration, a multi-input NExT method is utilized to retrieve the frequency response function needed by GRFP. A proof of the NExT method in the case of multi-input case is also provided in this paper.
Authors: Yue Li, Xiu Li Du, Chun E Sui
Abstract: Self-compacting Concrete (SCC) has many good properties such as high fluidity, good cohesiveness and resistance to segregation. Therefore, SCC should have higher durability compared to ordinary vibrated concrete in theory. At the same time, the cementitious materials and additives used in SCC are much more than that of used in ordinary concrete, which will cause SCC to generate shrinkage cracks easily and deteriorate its durability. So the durability of SCC should be studied further. In this paper, C30~C60 SCC were prepared, and then the permeability and reinforcing bar corrosion of reinforced self-compacting concrete were conducted. The results show that the permeability of SCC is lower which make sure the embedded reinforcing bars have high resistance to the corrosion.
Authors: Yan Li Shen, Xiu Li Du, Qing Shan Yang
Abstract: For estimating seismic response of pier-structure under near-fault ground motion, The typical pulse-type near-fault ground motion records were chosen to establish a record base, and three pier models with different natural period were established; The non-elastic response spectral displacement of ground motion was used to estimate the nonlinear response; The yield displacement of the nonlinear oscillator was defined based on the static pushover analysis result, and its influence on response estimation was studied. The study result is important for structural seismic response estimation by using the non-elastic response spectral displacement and the probability-based seismic performance evaluation.
Authors: Er Wei Guo, Zhen Bao Li, Hong Yu Zhou, Xiu Li Du
Abstract: Abstract. Size effect, referring to mechanical properties of materials change with the geometry changes, is the basic characteristic of brittle and quasi-brittle materials. Researches show that for the concrete material, compressive strength, split tensile strength and tensile strength decrease with the size of components increases, for RC structures, size effect also exists. The development and current situation in size effect are presented from three aspects, including concrete, RC members and the application of the code. And then, the developing trends of size effect of RC members are proposed.
Showing 1 to 10 of 18 Paper Titles