Cable Replacement Scheme for Low Tower Cable-Stayed Bridges Based on Sensitivity Analysis

Cable replacement is a key technique to solve the problems of cable corrosion and strand breakage. Cable removal causes structural changes. The choice of replacement method affects the safety of the bridge during cable replacement. A sensitivity analysis method was used to evaluate the force and deflection changes of Wohu Bridge. A reasonable method for the number and order of cable replacement was proposed; by comparing different cable removal schemes, it was revealed that the cable force and beam stress changes of the cables closest to the removed cable were the most significant. The results showed that the cable force increment of the surrounding cables was the largest when removing the longest cable. The structural impact change was small when removing the shortest cable. The maximum deflection at the top of the tower decreased with the decrease of the length of the removed cable. It was recommended to replace two cables symmetrically from the center of the tower, and the optimal replacement order was from the shortest cable to the longest cable. Furthermore, this paper also studied the influence of variable load on the cable replacement scheme, and demonstrated that the design scheme of opening part of traffic in this paper was safe and feasible

Cable Replacement Scheme for Low Tower Cable-Stayed Bridges Based on Sensitivity Analysis

Cable replacement is a key technique to solve the problems of cable corrosion and strand breakage. Cable removal causes structural changes. The choice of replacement method affects the safety of the bridge during cable replacement. A sensitivity analysis method was used to evaluate the force and deflection changes of Wohu Bridge. A reasonable method for the number and order of cable replacement was proposed; by comparing different cable removal schemes, it was revealed that the cable force and beam stress changes of the cables closest to the removed cable were the most significant. The results showed that the cable force increment of the surrounding cables was the largest when removing the longest cable. The structural impact change was small when removing the shortest cable. The maximum deflection at the top of the tower decreased with the decrease of the length of the removed cable. It was recommended to replace two cables symmetrically from the center of the tower, and the optimal replacement order was from the shortest cable to the longest cable. Furthermore, this paper also studied the influence of variable load on the cable replacement scheme, and demonstrated that the design scheme of opening part of traffic in this paper was safe and feasible

Research on the Performance of Regenerant Modified Cold Recycled Mixture with Asphalt Emulsions

In order to study the mechanical properties and effect of a regenerant on a cold recycled mixture with asphalt emulsions (CRMEs), the moisture susceptibility, high-temperature performance, low-temperature performance, dynamic mechanical properties and durability of CRMEs were analyzed and evaluated by immersion splitting strength tests, freeze-thaw splitting strength tests, rutting tests, semi-circle bending tests, uniaxial compression dynamic modulus tests and indirect tensile tests. Scanning electron microscopy (SEM) was used to analyze the micromorphology of CRMEs modified with regenerant. Finally, a comprehensive evaluation system of five different CRMEs was established based on the efficacy coefficient method to quantitatively analyze the comprehensive performance of the CRMEs. The test results showed that the regenerant can significantly improve the water immersion splitting strength, freeze-thaw splitting strength fracture energy density, and fatigue resistance of CRMEs. However, the addition of regenerant affected the high-temperature performance of the cold recycled mixture. The dynamic modulus of the CRMEs first increased and then decreased with regenerant content increasing. When the regenerant content was 8%, the dynamic modulus of the CRMEs was the highest. Adding styrene-butadiene rubber (SBR) latex can improve the high-temperature performance of CRMEs, but the moisture susceptibility, low temperature performance and fatigue resistance of the cold recycled mixture were not significantly improved, and the dynamic modulus of the mixture was reduced. Based on the efficacy coefficient method, the optimal content of regenerant is 8%. Regenerant are potential modifiers for cold recycled mixture that they can significantly improve the dynamic mechanical properties and durability

A 2.4 mW, 11.7±0.4dB, 3 to 5 GHz wide-band LNA for super-regenerative IR-UWB receiver

This paper presents a low-power wideband LNA for the Super-Regenerative IR-UWB receiver. To meet the LNA figures of merit, which are the wideband gain flatness, low power and low noise figure, we have proposed an improved input matching network, combined with the current-reuse technique and the power-constrained simultaneous noise and input matching (PCSNIM). Designed with CMOS 0.18 ??m technology, this 3-5 GHz LNA demonstrates the power-gain of 11.8dB with only ??0.4dB variation, a minimum NF of 3.5 dB and an input impedance matching lower than -10 dB across the 3-5 GHz band. The LNA core consumes only 2.4 mW from 1.2 V supply voltage and 2 mA current. ? 2013 IEEE.EI

A simulation training evaluation method for distribution network fault based on radar chart

In order to solve the problem of automatic evaluation of dispatcher fault simulation training in distribution network, a simulation training evaluation method based on radar chart for distribution network fault is proposed. The fault handling information matrix is established to record the dispatcher fault handling operation sequence and operation information. The four situations of the dispatcher fault isolation operation are analyzed. The fault handling anti-misoperation rule set is established to describe the rules prohibiting dispatcher operation. Based on the idea of artificial intelligence reasoning, the feasibility of dispatcher fault handling is described by the feasibility index. The relevant factors and evaluation methods are discussed from the three aspects of the fault handling result feasibility, the anti-misoperation correctness and the operation process conciseness. The detailed calculation formula is given. Combining the independence and correlation between the three evaluation angles, a comprehensive evaluation method of distribution network fault simulation training based on radar chart is proposed. The method can comprehensively reflect the fault handling process of dispatchers, and comprehensively evaluate the fault handling process from various angles, which has good practical value

Model for Predicting the Tortuosity of Transport Paths in Cement-Based Materials

The tortuosity of the pore structure is an important factor affecting medium (water and harmful ions) transport in cement-based materials. In this study, a new tortuosity model was established to reveal the effect of aggregate size, morphology, and graded media on the transport path in cement-based materials. Based on the stereological principle and the geometric algorithm, the distribution model of the ideal pebble and polygonal aggregate in cement-based materials was given first. Then, based on the image processing technology and MATLAB software, the morphology of the actual aggregate was also characterized to prove the similarity relationship between the ideal aggregate and actual aggregate. The reliability of the tortuosity model was verified by the mercury intrusion porosimetry test and data from other literature. Based on the tortuosity model, the influences of the aggregate particle shape parameters, hydration degree, and water-to-cement ratio on the tortuosity of the transport path were analyzed. Finally, the tortuosity model was further simplified to facilitate engineering application

A simulation training evaluation method for distribution network fault based on radar chart

In order to solve the problem of automatic evaluation of dispatcher fault simulation training in distribution network, a simulation training evaluation method based on radar chart for distribution network fault is proposed. The fault handling information matrix is established to record the dispatcher fault handling operation sequence and operation information. The four situations of the dispatcher fault isolation operation are analyzed. The fault handling anti-misoperation rule set is established to describe the rules prohibiting dispatcher operation. Based on the idea of artificial intelligence reasoning, the feasibility of dispatcher fault handling is described by the feasibility index. The relevant factors and evaluation methods are discussed from the three aspects of the fault handling result feasibility, the anti-misoperation correctness and the operation process conciseness. The detailed calculation formula is given. Combining the independence and correlation between the three evaluation angles, a comprehensive evaluation method of distribution network fault simulation training based on radar chart is proposed. The method can comprehensively reflect the fault handling process of dispatchers, and comprehensively evaluate the fault handling process from various angles, which has good practical value