Uneven settlement threshold of continuous beam pier based on analytic mapping relationship

Author(s):  
Yulin Feng ◽  
Shuai He ◽  
Lizhong Jiang ◽  
Wangbao Zhou ◽  
Xiang Liu
2021 ◽  
pp. 136943322110032
Author(s):  
Lin Ma ◽  
Wei Zhang ◽  
Steve C.S. Cai ◽  
Shaofan Li

In this paper, the dynamic amplification factors (DAFs) of high-speed railway continuous girder bridges are studied. The vehicle-bridge interactions (VBIs) of 13 concrete continuous girder bridges with spans ranging from 48 to 130 m are analyzed, the influences of the train speed, the train marshalling and the bridge fundamental frequency on the DAF are investigated, and the DAF design standard for high-speed railway bridges is discussed. The results indicate that for the continuous beam bridge whose fundamental frequency is less than 3.0 Hz, the maximum DAF is no more than 1.15; while for the bridge examples with a fundamental frequency larger than 3.0 Hz, the maximum DAF reaches 1.25 because the resonance occurs at high train speed. The empirical formulas of the DAFs in the Japan Railway Technical Research Institute (JRTRI) code could provide a conservative estimation of the DAFs of high-speed railway continuous bridges.


Author(s):  
Qiwen Jin ◽  
Zheng Liu

In-service bridges, under long-term service operational environment, are usually accompanied by different damage types. Traditional method for the measure point arrangement of in-service bridge SHM is usually based on engineering experience. A large number of SHM sensors are usually arranged on the structure, followed by a high engineering cost and a heavy maintenance task. These sensors will also produce large amounts of data, creating a challenge for operators requiring to deal with data processing in an effective manner. This study serves as a part of the series of studies on the measure point arrangement strategy of in-service bridge SHM. In this study, the SHM sensor measure point arrangement of in-service continuous girder bridge (a common structural style of high way bridge in China) is proposed. Two-span continuous beam, three-span continuous beam, and four-span continuous beam are taken as examples. Detailed comparison and verification are also performed with consideration of numerical simulation and previous studies. Different traffic speeds and different bridge spans are considered. The effect of different damage locations and different damage degrees are analyzed in detail. This study shows that a general similar trend can be observed for the structural robustness of in-service continuous girder bridge. The elements with smaller structural robustness of this kind of bridge are basically located around the middle cross section of side spans (first span and last span), followed by the middle span. Moreover, the numerical value of structural robustness of different elements in a continuous girder bridge is significantly different from each other, due to the complexity of the joint effect of different traffic speeds and damage locations. Therefore, the measure point should be generally arranged at the side span firstly, followed by the middle span. With consideration of the specific traffic speed and damage location in engineering application, a detailed analysis is also proposed for the further optimization of SHM sensor measure point arrangement. Once the elements are arranged in order of the numerical value of structural robustness, the SHM sensor measure point arrangement of this kind of bridge can be more targeted, and the number of sensors can also be greatly reduced.


2014 ◽  
Vol 36 (1) ◽  
pp. 310-334 ◽  
Author(s):  
WENMENG ZHANG ◽  
WEINIAN ZHANG

Concerning hyperbolic diffeomorphisms, one expects a better smoothness of linearization, but it may be confined by resonance among eigenvalues. Hartman gave a three-dimensional analytic mapping with resonance which cannot be linearized by a Lipschitz conjugacy. Since then, efforts have been made to give the ${\it\alpha}$-Hölder continuity of the conjugacy and hope the exponent ${\it\alpha}<1$ can be as large as possible. Recently, it was proved for some weakly resonant hyperbolic diffeomorphisms that ${\it\alpha}$ can be as large as we expect. In this paper we prove that this result holds for all $C^{\infty }$ weakly resonant hyperbolic diffeomorphisms.


1968 ◽  
Vol 94 (5) ◽  
pp. 1248-1249
Author(s):  
Bennosuke Tanimoto ◽  
Shotaro Natsume ◽  
Norikazu Yoshizawa

2017 ◽  
Vol 63 (1) ◽  
pp. 163-180 ◽  
Author(s):  
H.B. Wen ◽  
T. Zeng ◽  
G.Z. Hu

AbstractLaplace Transform is often used in solving the free vibration problems of structural beams. In existing research, there are two types of simplified models of continuous beam placement. The first is to regard the continuous beam as a single-span beam, the middle bearing of which is replaced by the bearing reaction force; the second is to divide the continuous beam into several simply supported beams, with the bending moment of the continuous beam at the middle bearing considered as the external force. Research shows that the second simplified model is incorrect, and the frequency equation derived from the first simplified model contains multiple expressions which might not be equivalent to each other. This paper specifies the application method of Laplace Transform in solving the free vibration problems of continuous beams, having great significance in the proper use of the transform method.


1955 ◽  
Vol 59 (535) ◽  
pp. 506-509
Author(s):  
A. M. Dobson

The Classical method of solution of the stability of an axially–loaded continuous beam is by means of the three moments equation, using the Berry Functions, which are functions of the axial load. As the axial load approaches a value equal to the critical value for a pin–jointed beam, the Berry Functions tend to infinity, and the use of the three moments equations —(i. e. treating the end fixing moments as the independent variables)—leads to certain difficulties in the complete solution of the problem.The major difficulty lies in the question of stability. The critical value is determined by the vanishing of the determinant of the coefficients of the fixing moments in the three moments equations. This value could be found by plotting the determinant against end load (c. f. Pippard and Pritchard). However, in a problem involving a large number of bays, the calculation necessary to do this is likely to be considerable, for there may be many branches to the curve.


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