Experimental Study on Creep and Mechanical Behavior of Modern Bamboo Bridge Structure

2012 ◽  
Vol 517 ◽  
pp. 141-149 ◽  
Author(s):  
Lei Li ◽  
Yan Xiao ◽  
Rui Zhen Yang
Keyword(s):  
Creep Test ◽  
Experimental Results ◽  
Original Structure ◽  
Loading Test ◽  
Long Span ◽  
Laminated Bamboo ◽  
Relative Air Humidity ◽  
Bridge Structures ◽  
Strength And Stiffness ◽  
Truck Load

A full-scale testing model of laminated bamboo truck load bridge was made based on the original structure. The mid-span deflection of CFRP-reinforced bamboo girders, temperature and relative air humidity were obtained through over three years creep test under self-weight, and the analysis based on experimental results was finished. The results indicate that the average creep deflection of the girders after three years is approximately 8-mm. In addition, the increase in temperature and humidity may contribute to creep. On the basis of creep test, a short-term loading test was carried out applied with dead load, and the bridge collapsed under the load of 18.5-t. By the analysis of the experimental results, it is realized that long span CFRP-reinforced bamboo girders have sufficient capacity to meet the strength and durability needs of practical use. Although CFRP layers could improve the performance of bamboo girders effectively, there is a decrease in strength and stiffness when considering the long-term performance. All these studies may contribute to improving the design of bamboo bridge structures, and some construction measures are suggested for the bamboo bridge according to the results of the experimental and analysis results.

Analysis and Test on Mechanical Properties of a Flexible Suspension Bridge

2013 ◽  
Vol 405-408 ◽  
pp. 1616-1622
Author(s):  
Guo Hui Cao ◽  
Jia Xing Hu ◽  
Kai Zhang ◽  
Min He
Keyword(s):  
Mechanical Properties ◽  
Suspension Bridge ◽  
Experimental Results ◽  
Suspension Bridges ◽  
Loading Test ◽  
Main Cable ◽  
Element Simulation ◽  
Static Loading Test ◽  
Geometric Nonlinear Analysis ◽  
Test Process

In order to research on mechanical properties of flexible suspension bridges, a geometric nonlinear analysis method was used to simulate on the experimental results, and carried on static loading test finally. In the loading test process, the deformations were measured in critical section of the suspension bridge, and displacement values of measured are compared with simulation values of the finite element simulation. Meanwhile the deformations of the main cable sag are observed under classification loading, the results show that the main cable sag increment is basically linear relationship with the increment of mid-span loading and tension from 3L/8 and 5L/8 to L/2 section, the main cable that increasing unit sag required mid-span loads and tension are gradually reduce in near L/4 and 3L/4 sections and gradually increase in near L/8 and 7L/8 sections and almost equal in near L/2, 3L/8 and 5L/8 sections. From the experimental results, the flexible suspension bridge possess good mechanical properties.

A Seismic Effective Method for Double-Layer Reticulated Shell Using Buckling-Restrained Braces

2010 ◽  
Vol 163-167 ◽  
pp. 2852-2856
Author(s):  
Chang Wu ◽  
Xiu Li Wang
Keyword(s):  
Double Layer ◽  
Seismic Performance ◽  
Linear Time ◽  
Ground Motions ◽  
Equations Of Motion ◽  
Time History ◽  
Original Structure ◽  
Loading Test ◽  
Strong Earthquakes ◽  
Buckling Restrained Braces

In this study a kind of buckling-restrained braces (BRBs) as energy dissipation dampers is attempted for seismic performance of large span double-layer reticulated shell and the effectiveness of BRBs to protect structures against strong earthquakes is numerically studied. The hysteretic curve of such members is obtained through the simulation of the cyclic-loading test, and the equations of motion of the system under earthquake excitations are established. BRBs are then placed at certain locations on the example reticulated shell to replace some normal members, and the damping effect of the two installation schemes of BRBs is investigated by non-linear time-history analyses under various ground motions representing major earthquake events. Compared with the seismic behavior of the original structure without BRBs, satisfactory seismic performance is seen in the upgraded models, which clarifies the BRBs can reduce the vibration response of spatial reticulated structure effectively and the new system has wide space to develop double layer reticulated shell.

Fire of steel and composite beam bridges

2019 ◽  
Author(s):  
Henryk Zobel ◽  
Wojciech Karwowski ◽  
Agnieszka Golubińska ◽  
Thakaa Al-Khafaji
Keyword(s):  
Fire Resistance ◽  
Composite Beam ◽  
Structural Integrity ◽  
Bridge Structure ◽  
Long Span ◽  
Long Span Bridge ◽  
Bridge Structures ◽  
Fire Scenarios ◽  
Design Construction ◽  
Cable Stayed Bridges

<p>The problem of bridge fires is growing. Because of a bad experience in Poland, it was decided to improve fire resistance of long span bridge structures, and of cable-stayed bridges in particular. Statistics shows that fire is a real threat to this kind of structure. They also confirm that the worst results of fire are for those with an orthotropic deck rather than with a concrete one. The basic problems to solve are how to predict fire resistance of a particular bridge and how to ensure safety and structural integrity of the bridge structure. Taking into account the fact that bridge standards do not include information relating to fire protection, and fire standards do not determine rules for design, construction and maintenance of such structures, there are no regulations for this problem. Fire scenarios are devoted to buildings, but the thermo-structural behavior of bridges is different.</p>

Lower Body Orthotic Calipers With Composite Braces

2018 ◽  
pp. 133-151
Author(s):  
Nisha Kumari ◽  
Kaushik Kumar
Keyword(s):  
Mechanical Properties ◽  
Surface Finish ◽  
Volume Ratio ◽  
Solid Modeling ◽  
Experimental Results ◽  
Lower Body ◽  
Corrosion Resistant ◽  
Lower Weight ◽  
Modeling Software ◽  
Strength And Stiffness

Composite based materials are finding application in a large number of research and engineering spectrum due to its better mechanical properties (strength and stiffness), inherent surface finish, easiness in fabrication and installation and corrosion resistant. They are very strong and firm, yet very light in weight due to which lower weight-to-volume ratio can be achieved and stiffness to weight is 1.5 times greater than the non-ferrous materials like Aluminum. The work is undertaken in two parts. First and foremost being modeling and virtual estimation of mechanical properties using CREO and ANSYS for currently used aluminum based calipers and fabrication of the composites and testing of the same. A comparison is performed between the virtual and experimental results and also the effectiveness of composite based calipers over Aluminum ones is studied. Here two polymeric based composites are proposed for fabrication which are thermoplast and thermoset based composites respectively. The braces are modeled using a solid modeling Software, CREO and the same is tested using ANSYS.

scholarly journals Performance of Notched Connectors for CLT-Concrete Composite Floors

Buildings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 122
Author(s):  
Minh Van Thai ◽  
Sylvain Ménard ◽  
Sidi Mohammed Elachachi ◽  
Philippe Galimard
Keyword(s):  
Element Model ◽  
Maximum Load ◽  
Edge Length ◽  
Experimental Results ◽  
Notch Depth ◽  
Long Span ◽  
Brittle Rupture ◽  
Screw Length ◽  
Floor Systems ◽  
And Behavior

CLT-concrete composite floor systems are a solution for timber buildings with a long-span floor. It yields a reduction of carbon footprint and even eco-friendly structure at the end of its service life. This study will evaluate the structural performance of notched connectors in the CLT-concrete composite floor, comprised of the serviceability stiffness, maximum load, and behavior at failure. The parameters of the test plan are the loaded edge length, the notch depth, the concrete thickness, and the screw length. Other secondary variables are also assessed, such as different loading sequences, speed of test, and timber moisture content. Experimental results prove that the performance of the connector depends significantly but not linearly on the notch depth and the length of the loaded edge. The connector with a deeper notch and a shorter heel will be stiffer and more robust, but it also tends to have a brittle rupture. The test results also help validate a solution for deconstructable connector systems. A nonlinear finite element model of the connector is built and validated versus the experimental results. It yields reasonably good predictions in terms of resistance and can capture the load-slip relationship.

Design and Manufacturing of a Multi-Stable Selectively Stiff Morphing Section Demonstrator

2019 ◽  
Author(s):  
D. Matthew Boston ◽  
Jose R. Rivas-Padilla ◽  
Andres F. Arrieta
Keyword(s):  
Structural Response ◽  
Experimental Results ◽  
Image Correlation ◽  
Stable States ◽  
Loading Test ◽  
Wing Section ◽  
Curved Structures ◽  
Trade Offs ◽  
Static Loading Test ◽  
And Performance

Abstract Morphing wings offer potential efficiency and performance benefits for aircraft fulfilling multiple mission requirements. However, the design of shape adaptable wings is limited by the inherent design trade-offs of weight, aerodynamic control authority, and load-carrying capacity. A potential solution to this trilemma is proposed by exploiting the stiffness adaptability of thin, curved structures which geometric instability results in two statically stable states. We design and manufacture a morphing wing section demonstrator composed of two compliant 3D printed ribs monolithically embedded with the proposed bi-stable elements. The demonstrator’s structural response is numerically modelled and compared with experimental results from a static loading test. A deflection field of the response under mechanical actuation is obtained through digital image correlation. Numerical and experimental results indicate the capability of the wing section to achieve four distinct stable configurations with varying global stiffness behavior.

OPTIMIZED LOW-EMBODIED AND OPERATIONAL CARBON SOLUTIONS FOR SINGLE-STORY INDUSTRIAL BUILDINGS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Dimitrios Moutaftsis ◽  
Shahaboddin Resalati ◽  
Martin Heywood ◽  
Raymond Ogden
Keyword(s):  
Building Envelope ◽  
Low Carbon ◽  
Considerable Saving ◽  
Carbon Reduction ◽  
Long Span ◽  
Embodied Carbon ◽  
Industrial Buildings ◽  
Inherent Strength ◽  
Strength And Stiffness ◽  
Traditional Construction

Detailed studies have been performed with the aim of determining optimum low-carbon solutions for buildings, and investigating the complex issues involved in their delivery. The evidence presented below suggests that building envelope specification has reached the point where the embodied carbon of any additional insulation balances, and may even outweigh, the corresponding savings in operational carbon. However, the extra material in the envelope has an inherent strength and stiffness that could be utilized to reduce the embodied carbon in the structure if appropriately designed. An extensive series of analyses was undertaken to (a) quantify the aggregated operational and embodied carbon related to modern envelope systems, and (b) evaluate the opportunities for embodied carbon reduction of the frame through the exploitation of the envelope’s structural capability. Particular attention was given to the use of long-span composite panels to reduce the number of supporting structural members. It was found that a considerable saving in embodied carbon is possible compared to traditional construction solutions. The study also suggested the absolute significance of combining operational and embodied carbon analyses, in order to demonstrate the effectiveness of carbon reduction strategies and requirements to shift away from “operational carbon only” methods. The focus of the initial phase of the work has been single-story industrial buildings, but the conclusions are applicable more broadly.

Behavior of Foam Particles Lightweight Concrete with Time

2018 ◽  
Vol 8 (04) ◽  
Author(s):  
Sohila A. El-Khouly ◽  
Amr H. Zaher ◽  
Ehab F. Sadek ◽  
Khalid M. Hilal
Keyword(s):  
Lightweight Concrete ◽  
Load Level ◽  
Experimental Results ◽  
Time Dependent ◽  
Flexural Behavior ◽  
Unit Weight ◽  
Experimental Program ◽  
Sustained Load ◽  
Polystyrene Foam ◽  
Loading Test

Lightweight Concrete with polystyrene foam particles (LWC) was obtained through the use of polystyrene foam as a partial aggregate’s replacement to reduce the concrete dry unit weight from 23 KN/m3 to 18.50 KN/m3. This research presents an experimental and theoretical investigation in the long-term behavior of LWC in compression and flexure. Two experimental programs were conducted; namely, creep and shrinkage of LWC under compressive loading test, and the time-dependent flexural behavior of reinforced LWC beams. The main variable in the first experimental program was the percentage of sustained load, while the main variables in the second experimental program were the percentage of sustained load and the percentage of compression reinforcement. Experimental results showed that LWC exhibits a significantly higher time-dependent strain (shrinkage plus creep) than normal weight concrete (NWC) under sustained compressive load and at the same compressive strength, with an increasing percentage about 9%. The creep strains of LWC seemed to be proportional to the stress to strength ratio. The timedependent deflections of the LWC beams were higher than those of NWC beams with increasing percentage about 25%. Addition of compression steel reinforcement (As`) to LWC beams reduced time-dependent deflections. Sustained load level and LWC time-dependent deflection were directly proportional. Finally, models and equations proposed by different codes were used to evaluate the obtained experimental results. From the theoretical study, it was found that Bazant-Baweja B3 Model gave superior shrinkage strains prediction for LWC. The ACI 209R-92 presented preferable predictions of creep strain and time-dependent deflection of LWC.

Detection of Shifts in GPS Measurements for a Long-Span Bridge Using CUSUM Chart

2016 ◽  
Vol 16 (04) ◽  
pp. 1640024 ◽  
Author(s):  
Ting-Hua Yi ◽  
Hong-Nan Li ◽  
Gangbing Song ◽  
Qing Guo
Keyword(s):  
Deformation Monitoring ◽  
Experimental Results ◽  
High Rate ◽  
Cumulative Distribution ◽  
Control Technique ◽  
Cusum Chart ◽  
Shewhart Chart ◽  
Long Span ◽  
Long Span Bridge ◽  
Shift Detection

Timely and correctly evaluating the quality of Global Positioning System (GPS) data is essential for reduction in the number of false alarms and missed detection of a GPS-based bridge deformation monitoring system. This paper investigates how to use the statistical process control technique, known as the cumulative sum (CUSUM) chart, for the detection of small but persistent shifts in the high-rate GPS carrier-phase measurements. First, a mathematical model for the shift detection based on the continuous hypothesis testing is established. The main features and implementation procedure of the CUSUM chart for the shift detection are then summarized, and the corresponding parameter selection method is discussed in detail. To meet the normality requirement of the CUSUM chart, a novel method that transfers the data to the Q-statistic by the estimated cumulative distribution functions is proposed according to the probability integral transform theory. This is followed by a simulation carried out to evaluate the detection performance of the CUSUM chart and exploit its advantages to the commonly used Shewhart chart for the high-rate GPS monitoring data with different shift sizes. Experimental results have showed that the CUSUM chart is sensitive to small persistent shifts compared to the Shewhart chart although it has a delay problem. The integration of CUSUM chart and Shewhart chart would be a reliable approach for the shift detection. Finally, an on-site dynamic monitoring experiment is carried out on a long-span bridge to validate the proposed approach’s effectiveness in detecting an actual deformation shift, and the experimental results proved to be very encouraging.

Sign in / Sign up

Export Citation Format

Share Document