scholarly journals Full-Scale Model Experimental Study of the Flexural Behavior of Hollow Slabs Strengthened by UHPC

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Jinzhi Zhou ◽  
Zihao Wen ◽  
Weiqi Mao ◽  
Chuheng Zhong ◽  
Kangning Wang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Vibration Frequency ◽  
Prestressed Concrete ◽  
Crack Width ◽  
Full Scale ◽  
Deformation Resistance ◽  
Flexural Behavior ◽  
Scale Model ◽  
Bending Performance ◽  
Load Tests

The hollow slabs strengthened by ultrahigh performance concrete (UHPC) composite beam show many advantages over traditional reinforcement methods. In this paper, full-scale model load tests were carried out on an nonstrengthened prestressed concrete hollow slab and an UHPC-strengthened prestressed concrete hollow slab, comparing the load deflection, crack width, bearing capacity, deformation resistance, and self-vibration frequency of the two. Static loading experimental results indicate that UHPC enhances the overall performance of prestressed concrete hollow slabs by decreasing deflection and crack width and improving bearing capacity. The strengthening effects of UHPC on a prestressed concrete hollow slab’s flexural behavior are also discussed, such as deflection, crack width, bearing capacity, deformation resistance, self-vibration frequency, flexural behavior, and cracking load. Deflection and crack width under a load of 800 kN decreased by 45.8% and 56.3%, respectively, and the initial self-vibration frequency, ultimate bearing capacity, and cracking load increased 19.2%, 21.4%, and 50%, respectively. The plane assumption can be made generally throughout the overall test process while using UHPC strengthening, which significantly constrains crack width and improves stiffness and deformation capacity. The UHPC layer and the prestressed concrete hollow slab were connected by shear studs to produce a good composite action between them, and the bending performance and bearing capacity of the whole structure were clearly improved. In addition to experiments, a validated numerical model is developed to verify the flexural performance of hollow slab strengthened by UHPC.

Experimental Research on Bending Performance of Concrete Beams Reinforced with CFRP-PCPs Composite Rebars

2013 ◽  
Vol 438-439 ◽  
pp. 804-806
Author(s):  
Jiong Feng Liang ◽  
Jian Bao Wang ◽  
Jian Ping Li
Keyword(s):  
Experimental Research ◽  
Prestressed Concrete ◽  
Crack Width ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Bending Performance ◽  
Reinforced Beams

The flexural behavior of concrete beams reinforced with CFRP-PCPs composite rebars was studied. Experimental results showed that the deflection of beams reinforced with highly prestressed prisms is at service loads coMParable to deflection of steel reinforced beam. Flexural cracks of CFRP-PCPs composite rebars reinforced beams are hairline before prism cracking, and widened after the prism cracking. When the concrete beam was reinforced with the prestressed concrete prisms, the crack width decreased as the prestress in the prism increased.

scholarly journals Flexural Behavior of a 30-Meter Full-Scale Simply Supported Prestressed Concrete Box Girder

2020 ◽  
Vol 10 (9) ◽  
pp. 3076 ◽  
Author(s):  
Jianqun Wang ◽  
Shenghua Tang ◽  
Hui Zheng ◽  
Cong Zhou ◽  
Mingqiao Zhu
Keyword(s):  
Prestressed Concrete ◽  
Mechanical Performance ◽  
Compressive Strain ◽  
Full Scale ◽  
Flexural Behavior ◽  
Destructive Testing ◽  
Scaled Model ◽  
Box Girder ◽  
Simply Supported ◽  
Prestressing Tendon

Compared with scaled-model testing, full-scale destructive testing is more reliable since the test has no size effect and can truly record the mechanical performance of the structure. However, due to the high cost, only very few full-scale destructive tests have been conducted on the flexural behavior of prestressed concrete (PC) box girders with girders removed from decommissioned bridges. Moreover, related destructive testing on the flexural behavior of a new precast box girder has been rarely reported. To investigate the flexural behavior and optimize the design, destructive testing of a 30-meter full-scale simply supported prestressed box girder was conducted at the construction site. It is illustrated that the failure mode of the tested girder was fracture of the prestressing tendon, and the corresponding maximum compressive strain in the top flange was only 1456 μ ε , which is far less than the ultimate compressive strain (3300 μ ε ). Therefore, the concrete in the top flange was not fully utilized. A nonlinear analysis procedure was performed using the finite strip method (FSM). The validity of the analysis was demonstrated by comparing the analytical results with those of the full-scale test in the field and a scaled model test in a laboratory. Using the developed numerical method, parametric analyses of the ratio of reinforcement were carried out. The prestressing tendon of the tested girder was increased from four strands to six strands in each duct. After the optimization of the prestressed reinforcement, the girder was ductile and the bearing capacity could be increased by 44.3%.

scholarly journals EFFECT OF DIFFERENT WOOD DOWELS ON MECHANICAL PROPERTIES OF TRIANGULAR GIRDER TRUSSES

Wood Research ◽  
2021 ◽  
Vol 66 (3) ◽  
pp. 477-488
Author(s):  
Liuliu Zhang ◽  
Cheng Chang ◽  
Shuming Yang
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Bearing Capacity ◽  
Static Load ◽  
Deformation Resistance ◽  
Stability Performance ◽  
Load Tests ◽  
Different Diameters

Static load tests were carried out on three kinds of triangular girder trusses with different diameter wood dowels, and the effects of that on the structure of girder trusses were discussed. It was found that there was a good synergy between the wood dowels and the girder trusses. Among the triangular girder trusses with different diameters, the 16 mm diameters had the best energy dissipation performance increased by 184% and deformation resistance of 0.73 mm; the 20 mm diameters had the best stability performance, the better bearing capacity of 60.42 kN and deformation resistance of 0.82 mm. The bearing capacity of the double girder trusses was 2.06-2.25 times that of two single trusses, which had the ability to ‘one plus one is greater than two’.

Non Destructive Testing of Low Profile Light Weight Track System

2010 ◽  
Author(s):  
Hassan Al Nageim
Keyword(s):  
Prestressed Concrete ◽  
Traffic Congestion ◽  
Full Scale ◽  
Scale Model ◽  
Light Rail ◽  
Destructive Testing ◽  
Low Profile ◽  
Track System ◽  
Multilayer Beams ◽  
Non Destructive

The paper presents the results of the responses of a concrete trough of a new lightweight rail track system (LR55) to full scale non destructive tasting. The system which is made from three main components; low profile steel rail, elastomeric pad and prestressed concrete trough is developed for light rail transits in cities streets, which can significantly help in improving the traffic flow, reducing the traffic congestion and thus providing opportunities for minimising serious environmental problems such as level of noise, vibration and air pollutions and in this regards it can be considered as environmentally friendly means of transport. A mathematical model was developed where the LR55 track system was treated as multilayer beams on elastic foundations, and the model was then validate experimentally through a series of non-destructive tests on full scale model subjected to a full scale service load specified by the current BS codes of practises.

Experimental Study of Bending Properties of CFRP Bars Concrete Beam and Crack Analysis

2014 ◽  
Vol 578-579 ◽  
pp. 687-690 ◽  
Author(s):  
Xue Qun Yao ◽  
Xin Sheng Xu
Keyword(s):  
Experimental Study ◽  
Influencing Factors ◽  
Calculation Method ◽  
Crack Width ◽  
Concrete Beam ◽  
Development Process ◽  
Flexural Behavior ◽  
Test Results ◽  
Bending Properties ◽  
Bending Performance

A test of the flexural behavior of concrete beam strengthened with sand-coated screwed CFRP bars was carried out to analyze the bending performance and cracking development process under staged loading, and different stage of crack distribution was plotted. Based on the test results, this paper discussed the crack mechanism and cracking feature of CFRP bars concrete beam under the load, and influencing factors of crack width and crack spacing were analyzed. Finally, calculation method of crack width was presented.

scholarly journals Mechanical Properties of Full-Scale Prestressed Concrete Beams with Thin Slab after Exposure to Actual Fire

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Chaowei Hao ◽  
Yanjiang Chen ◽  
Yu Tang ◽  
Laiyong Wang
Keyword(s):  
Bearing Capacity ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Rapid Identification ◽  
Ultimate Bearing Capacity ◽  
Full Scale ◽  
Bottom Surface ◽  
Thin Slab ◽  
Continuous Girder Bridge ◽  
Girder Bridge

To provide an effective basis and reference for applications of prestressed concrete thin-slab beams after a bridge fire, methods and principles of fire-resistant design, repair, and reinforcement of such beams were discussed. Taking a simple supported and continuous girder bridge of an expressway in service as a sample, appearance testing and nondestructive testing of the internal structure were carried out. Four representative full-scale prestressed concrete beams were selected. Through the comparative test of the ultimate bearing capacity of such beams, the laws of the deflection deformation, strain distribution, crack formation, and crack development were obtained. By combining with the finite element simulation and theoretical analysis, the ultimate bearing capacity, complex mechanical characteristics, and breakage feature and failure mechanism of such beams were studied. It was indicated by the results the following: (1) Prestress loss will cause height reduction of the concrete shear zone, which is one of the main reasons why the bending-shearing failure of such beams happened before the pure bending failure. (2) Under certain operating loads, brittle fracture is more likely to occur on the bottom surface of such beams when directly exposed to fire. (3) The bursting and spalling depth of concrete after being exposed to fire can be used as the characteristic parameters for the rapid identification of the bottom surface of such after-fire beams.

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.

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