Search

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-speed railway bridge piers with large stiffness, structure and construction are different from those of highway and municipal bridges and we need to conduct in-depth and systematic research to ensure whether a large number of existing highway and municipal bridge pier research results are applicable to socket type railway piers. The nonlinear finite element models of socket and castin-place double column hollow piers are established, and the correctness of the modeling method is verified by combining with the existing test results. By simulating the mechanical behavior of the pier under the quasi-static reciprocating action, the force-displacement curve of the hollow pier is obtained. The difference of hysteretic behavior between the socket pier and cast-in-place pier is compared. The reasonable range of the socket depth is determined based on the strain permeability effect and the development length of longitudinal reinforcement, and the calculation formula of the minimum socket depth is proposed. The results show that the bearing capacity difference between socket pier and cast-in-place pier is very small, the maximum difference is 2. 8% when the pier height is 5m and 10m. The stiffness degradation law of socket pier and cast-in-place pier is basically the same, the stiffness decreases with the increase of lateral displacement, and the stiffness degrades faster when the displacement is small, and it slows down when the displacement is large. The longitudinal reinforcement yields in the plastic hinge area and the strain permeation area below the cap top, and the strain decreases rapidly in the range of 400 mm below this area, the strain permeation area is the vulnerable part of the cap and socket pier. According to the calculation formula of the minimum socket depth proposed in this paper, the design value of the minimum socket depth of the hollow high-speed rail pier is 0. 5D(D is the outer diameter of the pier column). In order to ensure the safety of cap and plug bridge pier, reasonable structural measures should be taken to ensure the seismic performance of the pier in the strain permeation section, and it is recommended that the bearing depth of bridge pier in high intensity area should be greater than 0. 5D. [ABSTRACT FROM AUTHOR]

Due to hydraulic, mechanical, electromagnetic and other reasons, vibration will inevitably occur during the operation of the hydroelectric generating set. As the supporting structure of the hydroelectric generating set, the stability of the pier is very important. In this paper, the whole model of the pier, volute, draft tube and foundation is established. The amplitude of any part of the pier under the resonant load can be obtained by numerical simulation. On this basis, the response surface method is used by statistical method. The two parameters of the inner diameter and thickness of the pier are taken as the design variables, and the information weight method is used to replace the maximum amplitude of the pier in the vertical, radial and circumferential directions with a comprehensive objective function, and the comprehensive objective function is used as the optimization objective. The response surface model is established and the pier model is optimized. The results show that the maximum amplitude of the optimized pier in the vertical direction is reduced by 17.8%, the maximum amplitude in the circumferential direction is reduced by 4.7%, and the maximum amplitude in the radial direction is reduced by 1.4%. The recommended value range of the inner diameter of the pier is 1.73D1 - 1.83D1, and the recommended value range of the pier thickness is 0.50D1 - 0.63D1. The optimization design method of response surface can be effectively applied to the vibration reduction design of hydropower station pier. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Zhengzhou University: Engineering Science is the property of Editorial Office of Journal of Zhengzhou University: Engineering Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pier top displacement caused by temperature difference is an important index in the design. In order to fill the vacancy of applicable calculation formula for pier top temperature difference displacement in the current 2017 bridge code, the requirement of 0. 5 times displacement of temperature difference should be taken into account in the code to check pier top displacement. Based on the mechanical balance and geometric relationship, the pier top displacement calculation formulas in both linear and nonlinear temperature fields are deduced respectively through strict theoretical derivation. The equivalent linear temperature could be taken as 5 °C by displacement equivalence, and the equivalent linear temperature difference formula is used to check the general chart. The research results show that: (1) The calculation formula of pier top displacement of solid pier temperature difference derived theoretically can make up for the vacancy of calculation formula of 2017 bridge code; (2) Through the equivalent analysis of linear temperature field and nonlinear temperature field, the equivalent linear temperature difference is 5°C, which is consistent with the German Code; (3) For the pier with known temperature field, the calculation formula of nonlinear temperature field could be used, while for the pier without temperature field, the calculation formula of equivalent linear temperature field could be applied in design; (4) The check results of the solid pier general chart show that the displacement of pier top increases with the increase of pier height, and the horizontal displacement contributed by temperature difference could reach about 12% of the allowable bending angle. [ABSTRACT FROM AUTHOR]

Railway bridge is one of the essential components in a high-speed railway system and its health status has a significant impact on operational safety. Pier settlement can induce base plate void and hidden risk for train running. In this paper, the mechanism of the base plate void area due to the pier settlement in the longitudinal connected ballastless track system is analyzed On this basis, the analytic expression of the mapping relationship between pier settlement and void area of the base plate is deduced. The base plate deformation curve is calculated and compared with the finite element model results. Finally, the changing ranges of void areas and the spacing curve between base plate and bridge plate on account of the pier settlement in the longitudinal connected ballastless track system are analyzed. The results show that the analytical model can solve the void problem due to the pier settlement in the longitudinal connected ballastless track system. The void areas and the maximum spacing between base plate and bridge plate increase with the increase of settlement. When the settlement value reaches 35mm, the maximum spacing value reaches 0. 98mm. The bridge surface stiffness has little effect on the void area and the maximum spacing between base plate and bridge plate. [ABSTRACT FROM AUTHOR]

Local scour is the main factor leading to the instability of bridge piers. In this paper, the effect and influence of the retainer on local scour of bridge piers was studied and evaluated, including hydrodynamic characteristics and bed morphology characteristics. The results show that: the numerical simulation results are in good agreement with the experimental data; the distribution of averaged vertical velocity and bed shear stress change rule reveal that the existence of the retainer will reduce the velocity and the bed shear stress near the pier. The bed morphology distribution shows that the retainer reduces the local scour depth around piers, indicating that the retainer has a protective effect on the local scour around bridge piers. This study proposes a numerical simulation method to evaluate the effect of protective measures on piers, reducing the cost and development cycle, and providing reference data for construction. [ABSTRACT FROM AUTHOR]

In order to study the influence law of highway barrier on the impact effects of vehicle collision with bridge piers, so as to reasonably evaluate the safety of the actual pier under vehicle collision, finite element method was employed to carry out simulations of a large-size van-type truck (Ford F800 ) impacting with a low-grade concrete barrier (New Jersey barrier) and barrier-pier system. The motion pattern of the truck after collision with barrier, truck-pier collision mechanism under the protection of the barrier and the impact force peaks of the vehicle, etc., were mainly investigated, and the protective effect of the barrier was further discussed. The simulation results show that under the protection of the barrier, the impact of this van-type truck on the pier depends mainly on the cargo impact, while the engine generally does not collide with the pier. Under certain impact conditions, the peak impact force of the vehicle on the pier may exceed the peak of the impact force when the barrier is not set, even more than twice the latter. When the pier is close to the barrier (e. g., less than 1. 5 m), this low-grade concrete barrier may have a negative effect on the pier against vehicle collision. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Fuzhou University is the property of Journal of Fuzhou University, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to simulate the corroded reinforced concrete pier, the micro -crack of the concrete cover along the longitudinal reinforcement and reduction diameter of the reinforcement section are pre-set in the geometry model. The lateral anti-impact properties of the reinforced concrete pier in ocean environment are analyzed by using the dynamic explicit finite element software LS-DYNA. The translation process of the system energy, the time history value of strain gauge and failure mode of the corroded reinforced concrete pier are compared with the experiment results. The feasibility of the simplified finite element modeling and the validity of the numerical simulation are validated. It can provide computation references to reinforced concrete structures under impacting, and also provide evidence for the residual bearing capacity and durability test of reinforced concrete members. [ABSTRACT FROM AUTHOR]

The large structural analysis program MIDAS/CIVIL is introduced to establish a thin-walled rigid frame bridge model, and numerical simulation of time history analysis of seismic response of continuous rigid frame bridge under earthquake was performed based on the bridge superstructure weight load caused by the internal force of pier and top displacement for consideration by in different apparent wave velocity condition, change the beam number, size and connection way, The results show that the setting of the transverse beam will obviously change the force of the bridge pier, apparent wave velocity, the smaller the delay effect is more obvious, and the internal force is the first to decrease and then increase slowly with the increase of the wave velocity. The overall performance of the structure can be improved when set 0.55 times the size of the bridge pier on it's height of 1/2. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the prefabricated pier crack problems of Hongkong-Zhuhai-Macao Bridge CB03 tenders, we analyzed the internal temperature and strain condition of the bridge pier with the finite element simulation, and buried the internal temperature and strain sensors in the pier to do the in situ test of temperature and strain. We concluded that the root cause of cracks in the production of construction joints piers on the lower shrinkage of concrete are not synchronized, and developed a corresponding crack technical measures, which can well solve the crack problems. [ABSTRACT FROM AUTHOR]