Self-supporting tests in lattice joists subject to negative bending

Abstract During the construction of bridges, cantilever roofs and eaves, assembling formworks and scaffold that will support the slabs is a point of difficulty in the construction phase. Therefore, it is relevant the study of the lattice joists which serve as self-supporting formwork, supporting its weight, the weight of the fresh concrete, the weight of workers and the weight of concreting equipment. The analysis of the bearing capacity of lattice joists subject to negative bending with base concrete opening enables checking the maximum span that each lattice truss model bears, either cantilevered or between continuous spans with reduced or no scaffold. The concrete opening enables the monolithism between the slab and its support. This paper presents the results of tests on lattice joist with concrete opening. By the results analysis, formulations for designing the spacing between prop lines were found. The results are promising and indicate great possibilities of using lattice joists with concrete opening over the supports (beams), in order to optimize the slab shuttering.

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Investigation on Bearing Capacity of Reinforced Concrete Strut in Space Truss Model of Thick Piles Cap

Condition, Reliability, and Resilience Assessment of Tunnels and Bridges ◽

10.1061/47625(404)6 ◽

2011 ◽

Author(s):

Erjun Wu ◽

Jingdong Hou ◽

Youhao Ni ◽

Jiwei Wang

Keyword(s):

Reinforced Concrete ◽

Bearing Capacity ◽

Space Truss ◽

Truss Model

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Analysis of Bearing Capacity of Steel-High Strength Concrete Composite Beams

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.838-841.661 ◽

2013 ◽

Vol 838-841 ◽

pp. 661-664

Author(s):

Liang Li Xiao ◽

Ming Yang Pan ◽

Jian Wei Han

Keyword(s):

Bearing Capacity ◽

High Strength Concrete ◽

Influence Factors ◽

High Strength ◽

Composite Beams ◽

Finite Element Program ◽

Strength Concrete ◽

Element Program ◽

Negative Moment ◽

Negative Bending

It is very crucial to analyze the flexural bearing capacity of the steel-high strength concrete composite beams, but the combination on the flange of steel beam and their bearing capacity is limited with certain inevitability,in addition, in the negative bending regions of continuous composite beams, with the constant increase of load, the process of the whole structure will cause damages in the negative moment region. In order to avoid this kind of damages, we must use general finite element program ANSYS to analyze thebearing capacity of the steel and high strength concrete composite beams. Besides further studying the influence factors of bearing capacity, and ensuring the safety of our engineering performance can be in favor of the engineering structure.

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Research on flexural behavior of composite box continuous girder with corrugated steel webs and trusses

Advances in Structural Engineering ◽

10.1177/13694332211033957 ◽

2021 ◽

pp. 136943322110339

Author(s):

Jucan Dong ◽

Yiyan Chen ◽

Qingxiong Wu ◽

Aoxiang Hu ◽

Ruijuan Jiang ◽

...

Keyword(s):

Bearing Capacity ◽

Failure Modes ◽

Concrete Slab ◽

Flexural Behavior ◽

Bending Moments ◽

Test Beam ◽

Steel Tubes ◽

Element Analysis ◽

Flexural Bearing Capacity ◽

Negative Bending

A new type of composite structure, the composite box girder with corrugated steel webs (CSWs) and trusses, is proposed recently. In order to investigate the structural behavior under positive and negative bending moments, flexural tests of the continuous girder were carried out, and the failure modes, deformation patterns, strain distribution, and development of the concrete cracks were investigated. Finite element analysis was conducted to investigate the effect of the range of concrete in the steel tube and the thickness of CSWs on the flexural behavior. The experimental and numerical results show that the test beam has a good ductility and integrity under flexural load. The contribution of CSWs to the flexural bearing capacity is very small and can be neglected. Besides, the plane section assumption is still valid when only top concrete slab and bottom steel tubes are concerned. The concrete filled in bottom steel tubes increases the stiffness and the bearing capacity of the girder. Equations to calculate the flexural bearing capacity under positive and negative bending moments were put forward and then verified with experimental results.

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Mechanical Behavior and Calculation Method for RC Fifteen-Pile Cap of Mixed Passenger and Freight Railway Bridge

Advances in Civil Engineering ◽

10.1155/2020/8833256 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Hongmeng Huang ◽

Lu Cui ◽

Wei Lu

Keyword(s):

Mechanical Behavior ◽

Bearing Capacity ◽

Calculation Method ◽

Concrete Strength ◽

Reaction Force ◽

Load Bearing Capacity ◽

Load Bearing ◽

Strength Grade ◽

Truss Model ◽

Diameter Range

The thickness, reinforcement, and concrete strength grade of railway caps in China are generally determined according to the force, yet the method for calculating the force is unclear. To date, there is no desirable calculation method for analyzing the caps. Based on the fifteen-pile thick cap of mixed passenger and freight railway, the influencing factors on cap bearing capacity were analyzed using finite element method (FEM). The variations of load-bearing capacity and mechanical behavior of thick cap were characterized by introducing rigid angle α. Results indicated that ultimate load-bearing value of the cap increased linearly with the increase of concrete strength grade, and an increasing load-bearing capacity of the reinforcement distributed in the pile diameter range was larger than that of the uniform reinforcement; when the reinforcement ratio was 0.15%, it increased by 9.3%. The cap showed punching failure when α < 45°. The reaction force at each pile top under vertical load was not equal; thereby, the cap was not absolutely rigid. The principal compressive stress trajectories in the concrete were distributed in the range of connecting the pile and the outer edge of the pier, and the effective tensile stresses in the reinforcement were mainly distributed in the diameter range of pile and pile connection, which is in accord with the stress mode of the ordinary spatial truss model. Based on this, a spatial truss model applicable to the design of railway caps is proposed, and a method for calculating reaction force at pile top and formulas for calculating the bearing capacity of strut and tie were presented. The feasibility of the proposed method was also verified by comparison with FEM results.

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Study on Mechanical Performance of Deep Pile Cap Failure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.730.39 ◽

2015 ◽

Vol 730 ◽

pp. 39-42

Author(s):

Hong Lei Guo

Keyword(s):

Reinforced Concrete ◽

Bearing Capacity ◽

Failure Mechanism ◽

Mechanical Performance ◽

Load Bearing Capacity ◽

Truss Model ◽

Concrete Pile ◽

Pile Cap ◽

Complete Procedure ◽

Pile Caps

This paper presents the test of 3 reinforced concrete pile caps and the complete procedure of failure as well as the stressed mechanism, including the description of the occurrence of cracks. The influences of reinforcement types on load-bearing capacity are also probed. A spatial truss model is put forward and can explain satisfactorily some phenomena observed in the test and the failure mechanism is investigated.

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