scholarly journals Ultimate Moment Capacities of Round Prestressed Concrete Poles

2000 ◽  
Vol 16 (3) ◽  
pp. 127-132
Author(s):  
Ine-Wei Liu ◽  
Jun-Kai Lu
Keyword(s):  
Prestressed Concrete ◽  
Reduction Factor ◽  
Neutral Axis ◽  
Iterative Design ◽  
Area Reduction ◽  
Equilibrium Approach ◽  
Ultimate Moment ◽  
Compression Area ◽  
Satisfactory Manner

ABSTRACTAn alternative technique for the determination of ultimate moment capacities of round prestressed concrete poles is presented in this paper. The traditional concrete compression area of poles is determined using the conventional iterative design process, the compatibility and equilibrium approach. Moreover, the area of annulus defined by the neutral axis is multiplied by an area reduction factor. It is possible to use numerical methods to calculate the centroid of the reduced annulus. However, the concrete compression zone and strain variation in the longitudinal reinforcement makes the calculation awkward. This paper addresses the problem from a different perspective. No reference to area reduction factor is required in the course of locating the neutral axis. The results are compared in a very satisfactory manner with that obtained using PCI approach. The purpose is to provide formulations that can be easily computerized and implemented on relevant software for the design of round prestressed concrete poles.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

scholarly journals EM-Based Monitoring and Probabilistic Analysis of Prestress Loss of Bonded Tendons in PSC Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Zheheng Chen ◽  
Shanwen Zhang
Keyword(s):  
Probabilistic Analysis ◽  
Prestressed Concrete ◽  
Monitoring Methods ◽  
Prestress Loss ◽  
External Tendons ◽  
Material Environment ◽  
Key Factor ◽  
One Year

The prestress level is a key factor of prestressed concrete (PSC) beams, affecting their long-term serviceability and safety. Existing monitoring methods, however, are not effective in obtaining the force or stress of embedded tendons. This paper investigates the feasibility of elastomagnetic (EM) sensors, which have been used for external tendons, in monitoring the long-term prestress loss of bonded tendons. The influence of ambient temperature, water, eccentricity ratio, plastic duct, and cement grouts on the test results of EM sensors is experimentally examined. Based on the calibrated EM sensors, prestress loss of a group of PSC beams was monitored for one year. In order to further consider the high randomness in material, environment, and construction, probabilistic analysis of prestress loss is conducted. Finally, the variation range of prestress loss with a certain confidence level is obtained and is compared with the monitored data, which provides a basis for the determination of prestress level in the design of PSC beams.

scholarly journals A comparative study of beam design curves against lateral torsional buckling using AISC, EC and SP

2019 ◽  
Vol 15 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Vera V Galishnikova ◽  
Tesfaldet H Gebre
Keyword(s):  
Steel Structures ◽  
Reduction Factor ◽  
Steel Beams ◽  
Steel Beam ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Vertical Loading ◽  
Beam Design ◽  
Overall Stability

Introduction. Structural stability is an essential part of design process for steel structures and checking the overall stability is very important for the determination of the optimum steel beams section. Lateral torsional buckling (LTB) normally associated with beams subject to vertical loading, buckling out of the plane of the applied loads and it is a primary consideration in the design of steel structures, consequently it may reduce the load currying capacity. Methods. There are several national codes to verify the steel beam against LTB. All specifications have different approach for the treatment of LTB and this paper is concentrated on three different methods: America Institute of Steel Construction (AISC), Eurocode (EC) and Russian Code (SP). The attention is focused to the methods of developing LTB curves and their characteristics. Results. AISC specification identifies three regimes of buckling depending on the unbraced length of the member ( Lb ). However, EC and SP utilize a reduction factor (χ LT ) to treat lateral torsional buckling problem. In general, flexural capacities according to AISC are higher than those of EC and SP for non-compact sections.

Assessment of Load-Bearing Capacity of Bridges

2017 ◽  
Vol 259 ◽  
pp. 113-118 ◽  
Author(s):  
Jaroslav Navrátil ◽  
Michal Drahorád ◽  
Petr Ševčík
Keyword(s):  
Bearing Capacity ◽  
Prestressed Concrete ◽  
Iterative Solution ◽  
Concrete Bridges ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Prestressed Concrete Bridges ◽  
Existing Structures ◽  
Non Linear

The paper aims to the determination of load-bearing capacity of reinforced/prestressed concrete bridges subjected to the combination of all components of internal forces according to Eurocode standards for assessment of existing structures. Undoubtedly bridge load rating is laborious hand-iterative process, especially when it comes to reinforced and/or prestressed concrete bridges. The engineer can spend days and weeks trials and errors in the estimation of bridge load-carrying capacity. The problem lies in the determination of load-bearing capacity of cross-section subjected to the combination of normal and shear forces, bending and torsional moments. Due to the different effects of permanent and variable loads and the non-linear behavior of structural materials, the problem becomes non-linear and its solution requires the use of suitable iterative method. Optimized iterative solution was implemented into IDEA StatiCa software and the results are presented in this paper.

Effects of driving forces and bending fatigue on structural performance of a novel concrete-filled fibre-reinforced-polymer tube flexural pile

2006 ◽  
Vol 33 (6) ◽  
pp. 683-691 ◽  
Author(s):  
Karim Helmi ◽  
Amir Fam ◽  
Aftab Mufti ◽  
J Michael Hall
Keyword(s):  
Prestressed Concrete ◽  
Driving Forces ◽  
Marginal Effect ◽  
Lateral Loads ◽  
Bending Fatigue ◽  
Reinforced Polymer ◽  
Composite Pile ◽  
Fibre Reinforced Polymer ◽  
Ultimate Moment ◽  
Prestressed Piles

The effects of driving forces and high-cycle fatigue on the flexural performance of a novel pile consisting of a concrete-filled glass-fibre-reinforced polymer (GFRP) tube (CFFT) are investigated. A 367 mm diameter CFFT pile was driven and then extracted from the ground. Two 6 m segments cut from the upper and lower ends of the pile were tested to failure under monotonic bending and compared with a similar undriven CFFT pile. In addition, a 625 mm diameter CFFT and a conventional 508 mm square prestressed concrete pile of similar moment capacities, both 13.1 m long, were driven, tested in the field under lateral loads, and compared. It was found that driving forces have a marginal effect (about 5% reduction) on the flexural strength of CFFT piles. Also, CFFT piles have larger deflections than prestressed piles do. Because the GFRP tube is the sole reinforcement for the CFFT system, a comprehensive fatigue test program was conducted: coupons cut from the tube were tested under cyclic loading at various stress levels (20%–60% of ultimate) to establish the S–N curve and stiffness-degradation characteristics of the tube. A full-scale 367 mm diameter and 6 m long CFFT pile was tested under reversed cyclic bending at 60% of ultimate moment to validate the coupon test results. It is recommended that the service moment be limited to 20%–30% of ultimate moment to achieve at least 1 million cycles.Key words: composite pile, CFFT, driving, bending, fatigue, cyclic, FRP, tension.

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