scholarly journals Study on Mechanical Performance of Prestressed UHPFRC U-Beam Bridges

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Mengying Liu ◽  
Eugen Brühwiler ◽  
Fengkun Cui ◽  
Yue Xu
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Failure Process ◽  
Bending Moment ◽  
Full Scale ◽  
Fiber Reinforced Concrete ◽  
Scale Model ◽  
Bottom Plate ◽  
Analysis And Design ◽  
Flexural Performance

The forms of U-shaped UHPFRC beams have not been investigated for the highway footbridge. Compared with the traditional section forms, the U-shaped UHPFRC beams can reduce the material consumption under the condition of providing the same bearing capacity. Furthermore, prestressed U-shaped UHPFRC beams are rarely reported in the existing research. This paper explores the flexural behavior of prestressed ultrahigh-performance fiber-reinforced concrete (UHPFRC) beam bridge having unique design and the material properties of prestressed reinforcement combined with UHPFRC. Based on the unique shape of the U beam, the flexural performance test of the full-scale model of the prestressed UHPFRC U beam is conducted. Then, the finite element model considering material nonlinearity and structural ductility is established using Midas FEA software. Finally, the failure mode, failure process, cracking moment, ultimate moment, and strain of the full-scale model are studied. The calculation formulas of the flexural capacity of UHPFRC U beam considering ductile failure are derived. The comparative analysis results show that the prestressed UHPFRC U beam has an excellent flexural performance. The bending failure of a U-shaped beam belongs to the group of ductile failures, which is characterized by the main crack along the central rib and the loading center, which is accompanied by multiple microcracks. The failure process can be divided into four stages: linear deformation, microcracks development, main cracks development, and bearing capacity decline. The incorporation of steel fiber and the interaction between UHPFRC and reinforcement can effectively reduce the development of cracks. The U-beam bending moment is 50–55% of the ultimate bending moment. In the UHPFRC bridge design, the deformation can be used as a control index, and material advantages of the UHPFRC can be used to a certain extent. The strain-hardening characteristics of the UHPFRC are obvious in the loading process. The finite element analysis results show that the maximum strain value appears at the central rib, followed by the transverse strain value of the bottom plate, while the minimum strain is the longitudinal strain value of the bottom plate. The deformation of the rib plate is the largest, and the strain of the other measuring points changes slowly. The farther away from the center the measurement point is, the slower its strain changes. Therefore, the load is mainly caused by the central rib and the loading center plate. With the increase in the deformation, the load on both sides continuously moves to the central rib along the plate surface. This study can provide a useful reference for theoretical analysis and design of prestressed U-UHPFRC bridges.

scholarly journals An Experimental Study of Horizontal Bearing Capacity of Vertical Steel Floral Tube Micropiles with Double Grouting

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Kaiyang Wang ◽  
Yanjun Shang
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Slip Surface ◽  
Bending Moment ◽  
Shear Capacity ◽  
Soil Reinforcement ◽  
Scale Model ◽  
Soil Pressure ◽  
Floral Tube ◽  
Grouting Pressure

This paper examines the performance of a novel technology, vertical steel floral tube micropiles with double grouting. It is the combination of micropile technology and double grouting technology. A large-scale model tank was applied to impart horizontal bearing capacity, and the slope soil pressure and flexural performance of the micropile were investigated under four experimental conditions. The peak grouting pressure during the double grouting process was defined as the fracturing pressure of the double grouting, and it was positively correlated to the interval time between first grouting and secondary grouting. Compared with traditional grouting, double grouting increased the horizontal bearing capacity of the single micropile with the vertical steel floral tube by 24.42%. The horizontal bearing capacity was also 20.25% higher for the structure with three micropiles, compared with a 3-fold value of horizontal sliding resistance. In the test, the maximum bending moment acting on the pile above the sliding surface was located 2.0–2.5 m away from the pile top, and the largest negative bending moment acting on the pile below the slip surface was located 4.0 m away from the pile top. The ultimate bending moment of the single pile increased by 12.8 kN·m with double grouting, and the bending resistance increased by 96.2%. The experimental results showed that the double grouting technology significantly improved the horizontal bearing capacity of the micropile with the steel floral tube, and the soil reinforcement performance between piles was more pronounced. Also, the shear capacity and the flexural capacity were significantly improved compared with the original technology.

scholarly journals Mechanical Properties of Concrete Pipes with Pre-Existing Cracks

2020 ◽  
Vol 10 (4) ◽  
pp. 1545
Author(s):  
Zongyuan Zhang ◽  
Hongyuan Fang ◽  
Bin Li ◽  
Fuming Wang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Bearing Capacity ◽  
Three Dimensional ◽  
Compressive Load ◽  
Full Scale ◽  
Element Analysis ◽  
Concrete Pipes ◽  
Concrete Pipe ◽  
Full Scale Tests

Concrete pipes are the most widely used municipal drainage pipes in China. When concrete pipes fall into years of disrepair, numerous problems appear. As one of the most common problems of concrete pipes, cracks impact on the deterioration of mechanical properties of pipes, which cannot be ignored. In the current work, normal concrete pipes and those with pre-existing cracks are tested on a full scale under an external compressive load. The effects of the length, depth, and location of cracks on the bearing capacity and mechanical properties of the concrete pipes are quantitatively analyzed. Based on the full-scale tests, three-dimensional finite element models of normal and cracked concrete pipes are developed, and the measured results are compared with the data of the finite element analysis. It is clear that the test measurements are in good agreement with the simulation results; the bearing capacity of a concrete pipe is inversely proportional to the length and depth of the crack, and the maximum circumferential strain of the pipe occurs at the location of the crack. The strain of the concrete pipe also reveals three stages of elasticity, plasticity, and failure as the external load rises. Finally, when the load series reaches the limit of the failure load of the concrete pipe with pre-existing cracks, the pipe breaks along the crack position.

Study on Buckling of an H-Shaped Steel Member with Initial Geometric Imperfection

2012 ◽  
Vol 204-208 ◽  
pp. 3226-3229
Author(s):  
Peng Niu ◽  
Gang Yang ◽  
Chun Fu Jin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Bearing Capacity ◽  
Compressive Load ◽  
Bending Moment ◽  
Ultimate Bearing Capacity ◽  
Geometric Imperfection ◽  
Elastic Plastic ◽  
Axial Compressive Load ◽  
Initial Geometric Imperfection

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for an H-shaped member are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact by initial geometric imperfections on the H-shaped steel member under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. The results of the example show that the presence of initial imperfections reduces the ultimate bearing capacity of the steel member to a great extent. It is also found that the influence of the initial geometric imperfection on the ultimate bearing capacity of member is smaller when the bending moment increases.

Research on Precast Roof Truss of Prestressed Concrete Square Pile

2014 ◽  
Vol 488-489 ◽  
pp. 359-364
Author(s):  
Jia Bin Liu ◽  
Zheng Xing Guo ◽  
Le Qi Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Prestressed Concrete ◽  
Control Method ◽  
Optimal Solution ◽  
Bending Moment ◽  
Scale Model ◽  
Element Analysis ◽  
Design Load ◽  
Roof Truss

The precast roof truss of prestressed concrete square pile is a new self-balancing system composed of prestressed concrete square pile, strut and steel tension rod. Based on finite element analysis methods, the bending moment and deformation under most unfavorable design load was checked upon crack resistant bending moment to verify its engineering feasibility, the optimal prestressed value was analyzed to get the camber of the top chord beam, and the optimal tension method for bottom chord tension rod was determined. Compared with finite element analysis results, the full scale model test was carried out to further verify its engineering feasibility and some optimization recommendation was proposed. It suggests that the tension order of middle section before diagonal rod, initial prestressed value of 10t, and prestressed control method of monitoring camber at midspan is the most reasonable and optimal solution.

Research on the Bearing Capacity of High-Strength Steel Tubular H-Joints in High-Voltage Transmission Lines

2014 ◽  
Vol 513-517 ◽  
pp. 4123-4126 ◽  
Author(s):  
Yun Xu
Keyword(s):  
Bearing Capacity ◽  
Transmission Lines ◽  
Local Buckling ◽  
Bending Moment ◽  
High Strength ◽  
Steel Tube ◽  
Scale Model ◽  
Tube Plate ◽  
Control Factors ◽  
Local Strength

The steel tube-plate joints are widely applied in tall-slender tower of transmission line engineering,but there are few studies at home and abroad. In this paper,experimental study with full-scale model and analysis based on FEM were carried out on the ultimate bearing capacity of typical h-joints , and the results showed that the bending moment was transferred to the chord from the ear-plate of a narrow area, which led to local buckling on the chord wall , so the local strength of chord is one of the most important control factors in the design of this typical joint;thus the bearing capacity can improve by enhancing the strength of steel or increasing the thickness of ear-plate. In view of the phenomenon that stress concentration is easy to emerge at the intersection of the steel tube-plate joints, some improvement measures for the connections are put forward,such as adding outer half-ring stiffening plates , adding outer-ring plates , adding inner-ring plates, and revising ear-plates to smooth the concave angle , etc.

Analysis and Design of Cable-Membrane Architectural Structure

2013 ◽  
Vol 351-352 ◽  
pp. 22-25
Author(s):  
Na Li ◽  
Jing Ji
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Membrane Structure ◽  
Simulation Analysis ◽  
Full Scale ◽  
Ansys Software ◽  
Form Finding ◽  
Analysis And Design ◽  
Construction Methods ◽  
Temperature Loads

The test and theoretical analysis of full-scale cable membrane structure are less, and the author carried out simulation analysis of full scale cable-membrane structure with 30m by ANSYS software, finite element realistically model of cable membrane structure was established based on the assumption. By applying the temperature loads form-finding of membrane is achieved. By self-equilibrium nonlinear solution, the deformation and the stress distribution of this structure are gotten, finally construction methods of the node and the supporting members are given. These can provide the theory support for improving the spatial structure, and can provide reference for design and construction of similar engineering.

Study on Safety of the Fastener Tubular Steel Scaffolding

2011 ◽  
Vol 368-373 ◽  
pp. 771-776 ◽  
Author(s):  
Chang Ming Hu ◽  
Fang Fang Song ◽  
Xiao Zhou Fan
Keyword(s):  
Finite Element ◽  
Initial Imperfection ◽  
Full Scale ◽  
Scale Model ◽  
Test Results ◽  
Lateral Loads ◽  
Safety Control ◽  
Research Results ◽  
Initial Imperfections ◽  
Finite Element Software

Based on analysis of five different conditions’ full scale model tests of the fastener tubular steel scaffolding, the paper introduces that notional lateral loads can imitate the effect which generalized imperfections of the falsework(initial imperfections, node semi-rigid and so on) give the bracket’s stability capacity. According to the finite element software ANSYS, the falseworks’ stability capacities of different conditions have been imitated and analysed, Analysis results compare with test results. The final result indicates that it is reasonable that notional lateral loads in certain scope can imitate generalized initial imperfection. Research results can be used for on-site t technical personnels’ design and safety control.

Influence of the Initial Imperfection on the Buckling of Steel Member Wrapped by Carbon Fibre

2012 ◽  
Vol 166-169 ◽  
pp. 738-742 ◽  
Author(s):  
Peng Niu ◽  
Gang Yang ◽  
Chun Fu Jin ◽  
Xinxiang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Carbon Fibre ◽  
Bearing Capacity ◽  
Compressive Load ◽  
Bending Moment ◽  
Ultimate Bearing Capacity ◽  
Geometric Imperfection ◽  
Axial Compressive Load ◽  
Initial Geometric Imperfection

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial geometric imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for an H-shaped member with flange outsides wrapped by carbon fibre are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact of the initial geometric imperfection on the H-shaped steel member wrapped by carbon fibre under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. Compared the reinforced effect of the carbon fibrer to the perfection member with the defect member, we find that the former is higher than the latter. The results of the example also show that the presence of initial geometric imperfection reduces the ultimate bearing capacity of the steel member to a great extent. The influence of defect member gradually decreases when the given moment rises.

scholarly journals Experimental Study and Numerical Simulation on Failure Process of Reinforced Concrete Box Culvert

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yafeng Gong ◽  
Yulin Ma ◽  
Guojin Tan ◽  
Haipeng Bi ◽  
Yunze Pang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Failure Process ◽  
Side Wall ◽  
Load Test ◽  
Tensile Failure ◽  
Scale Model ◽  
Road Transportation ◽  
Contact Behaviour

Culvert is an important part of roads whose healthy operation is related to the efficiency and safety of road transportation. Therefore, it is very important to evaluate the safety of culvert structure by load test. Four types of prefabricated reinforced concrete box culverts (integral BC, round hinged BC, flat seam BC, and mortise BC) were designed in this paper. By designing a scale model test, the sensor system was used to test the mechanical properties of BC, which included dial indicators, strain gauges, and a pressure sensor. The finite element analysis based on material nonlinearity and contact nonlinearity of round hinged BC and integral BC was carried out. After validating the finite element models, mechanical properties of reinforcement and concrete of BCs were analyzed. The experimental results show that the failure mode of BC was tensile failure of concrete at the bottom of top slab under bending action, and integral BC had the maximum carrying capacity. The contact behaviour of sliding and rotating at hinge joints caused the first principal tensile stress of concrete at the internal surface of the side wall below hinge joints.

Development of Reusable High-Molecular-Weight–High-Density Polyethylene Crash Cushions

1996 ◽  
Vol 1528 (1) ◽  
pp. 11-27 ◽  
Author(s):  
J. F. Carney ◽  
M. I. Faramawi ◽  
S. Chatterjee
Keyword(s):  
Molecular Weight ◽  
Finite Element ◽  
Finite Element Modeling ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Full Scale ◽  
High Density ◽  
Scale Model ◽  
Model Experiments ◽  
Element Modeling

The development of a family of low-maintenance, reusable crash cushions that employ energy dissipaters made of high-molecular-weight–high-density polyethylene is described. This “smart” energy dissipating thermoplastic is self-restorative and reusable and possesses excellent hysteresis characteristics. The design process involved quasi-static and impact scale model experiments, finite-element modeling, and a full-scale crash testing program conducted according to the guidelines of NCHRP Report 350. A treatment of all of these design components is presented. It is demonstrated that scale model experiments and finite-element modeling are cost-effective tools whose employment can minimize the number of costly full-scale crash tests required to qualify devices as acceptable for use on the National Highway System.

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