Study on Mechanical Mode of Frame Column Underpinning Joint

2011 ◽  
Vol 255-260 ◽  
pp. 624-628 ◽  
Author(s):  
Ai Hua Du ◽  
Xin Zhang
Keyword(s):  
Failure Mode ◽  
Orthogonal Experiment ◽  
Concrete Strength ◽  
Joint Stress ◽  
Shear Span ◽  
Steel Bar ◽  
Moving Beam ◽  
Before And After ◽  
Key Factor ◽  
Two Stages

An orthogonal experiment of sixteen frame column underpinning joints was introduced, experiment was designed by a normal table of “five-factor and four-level”, five factors referred to ratio of shear-span of moving beam, ratio of underpinning beam stirrup steel bar, underpinning beam longitudinal steel bar parameter, concrete strength, and planted reinforcement, in addition every factor had four experiment datum. Then, the underpinning joint stress mechanism and failure mode was determined, based on the experiment the conclusion was drawn that the ratio of shear-span of moving beam was the key factor to the joint failure mode; and the failure course was divided two stages which were before and after interface punching slip by theoretical analysis, for the phase before interface punching slip a space and plane “tension-bar-arch” mechanical model was presented for the underpinning joint, then mechanic analysis was put into the models, and two series theoretical calculation correlations for this underpinning joint were obtained, by comparison with the test result one model and one formula was choose, this theoretical results were agreement with experiments results.

Research on Bearing Capacity of Column Underpinning Joint of Frame Structure Moving

2011 ◽  
Vol 243-249 ◽  
pp. 426-430 ◽  
Author(s):  
Ai Hua Du ◽  
He Qi Tang
Keyword(s):  
Bearing Capacity ◽  
Mechanical Model ◽  
Frame Structure ◽  
Deep Beam ◽  
Interface Shear ◽  
Joint Stress ◽  
Failure Type ◽  
Before And After ◽  
Interface Slip ◽  
Two Stages

An experiment of sixteen frame column underpinning joints of frame structure moving was introduced, the experiment sample failure phenomena and failure type was obtained. The type was like “deep beam” failure type-“tension bar arch”, and the last failure place occurred on the interface of column and beam. Then, the underpinning joint stress mechanism and failure mode was determined based on the experiment’s conclusion. In addition, the failure course of joint was divided two stages which were before and after interface punching slip by theoretical analysis, for the stage before interface punching slip a space “tension-bar-arch” mechanical model was presented for the underpinning joint, then theoretical bearing capacity equation for this underpinning joint were obtained. At the same time, for the stage of interface after punching slip, the theory of interface shear was put into the analysis of joint, then interface bearing capacity equation was obtained for this stage. At last the height equation was obtained by the analysis of the stage of after interface slip.

scholarly journals Shipboard Power Management for Failure Mode Using the Hybrid MPC Approach

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2915
Author(s):  
Xiuyan Peng ◽  
Bo Wang ◽  
Lanyong Zhang ◽  
Peng Su
Keyword(s):  
Model Predictive Control ◽  
Power Systems ◽  
Power Management ◽  
Failure Mode ◽  
Hybrid Model ◽  
Predictive Control ◽  
Minimum Principle ◽  
Management Control ◽  
Shipboard Power ◽  
Two Stages

Shipboard integrated power systems, the key technology of ship electrification, call for effective failure mode power management control strategy to achieve the safe and reliable operation in dynamic reconfiguration. Considering switch reconfiguration with system dynamics and power balance restoration after reconfiguration, in this paper, the optimization objective function of optimal management for ship failure mode is established as a hybrid model predictive control problem from the perspective of hybrid system. To meet the needs for fast computation, a hierarchical hybrid model predictive control algorithm is proposed, which divides the original optimization problem into two stages, and reduces the computation complexity by relaxing constraints and the minimum principle. By applying to a real-time simulator in two scenarios, the results verify the effectivity of the proposed method.

scholarly journals Eco-Friendly Fired Brick Produced from Industrial Ash and Natural Clay: A Study of Waste Reuse

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 877 ◽  
Author(s):  
Neslihan Doğan-Sağlamtimur ◽  
Ahmet Bilgil ◽  
Magdalena Szechyńska-Hebda ◽  
Sławomir Parzych ◽  
Marek Hebda
Keyword(s):  
Compressive Strength ◽  
Bottom Ash ◽  
Unit Weight ◽  
Waste Reuse ◽  
Industrial Solid Waste ◽  
Second Stage ◽  
Before And After ◽  
Fired Bricks ◽  
Two Stages ◽  
And Storage

Bottom ash (BA) is an industrial solid waste formed by the burning of coal. The environmental problems and storage costs caused by this waste increase with every passing day. In this study, the use of BA as an additive (clay substitute) in fired brick production was investigated. The study consisted of two stages. In the first stage, cylinder blocks were produced from clay used in brick production. The second stage was the examination of the experimental substitution of clay with 10, 20, 30 and 40% BA. Samples were fired at 900, 1000, 1100 and 1150 °C to produce fired brick samples. The unit weight, compressive strength (before and after freeze–thawing) and water absorption were analyzed for the samples. The unit weight values decreased in the samples containing BA. The mechanical properties met the conditions prescribed in the relevant standards; i.e., all of the samples fired at 1100 and 1150 °C had a sufficient compressive strength over 20 MPa. The high potential of fired bricks for the construction industry was proved. BA can be used as a clay substitute, while the developed protocol can be used to effectively produce fired bricks.

scholarly journals Experimental Study on the Shear Performance of Shallow Hinge Joints for Prefabricated Hollow Slab Bridges

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Hanbin Yi ◽  
Chuanxi Li ◽  
Li Dai
Keyword(s):  
Shear Stress ◽  
Failure Mode ◽  
Shear Failure ◽  
Internal Force ◽  
Force Transmission ◽  
Transmission Performance ◽  
Joint Stress ◽  
Hinge Joint ◽  
Vehicle Load ◽  
Joint Fracture

To investigate whether shallow hinge joint fracture was caused by shear stress or flexural stress, during the demolition and reconstruction of Xiaojiang River bridge, two original girders were collected and shipped to the lab, and the shallow hinge joint between the two girders was rebuilt. Tests were performed to investigate the cracking load, failure mode, and force transmission performance of the hollow slab girder and shallow hinge joint under vehicle load. The test result shows that under eccentric load, when the load increases to 365 kN, the midspan bottom slab of the testing girder starts to fracture; as the load increases to 560 kN, the roof slab of the testing girder starts to fracture; the hinge joint has a maximum horizontal opening of 0.153 mm and vertical relative displacement of 0.201 mm; during the entire test loading process, the shallow hinge joint structure does not develop fracture and shear failure; and the shallow hinge structure demonstrates excellent shear stress transmission performance. In addition, based on hinge slab theory, the hinge joint internal force under vehicle load was calculated. Based on ACI 318-05 specification, CAN/CSA-S6-00, and JTG D61-2005, the hinge joint shear bearing capacity was calculated. Hinge joint stress resistances calculated from the three specifications all exceed the internal force. Among them, the calculation results from ACI 318-05 and CAN/CSA-S6-00 are similar, while the result from JTG D61-2005 specification significantly exceeds the internal force, which is mainly because the designed concrete direct shear strength fvd in the Chinese specification does not consider factors such as bonding surface coarseness, concrete pouring sequence, and material properties. Theoretical calculations and tests show that the actual failure mode of the shallow hinge joint in prefabricated hollow slab girder bridges is not caused by shear stress.

scholarly journals Assessment of risks in the field of safety, quality and environment in post-harvest line

2016 ◽  
Vol 61 (Special Issue) ◽  
pp. S26-S36 ◽  
Author(s):  
M. Žitňák ◽  
K. Kollárová ◽  
M. Macák ◽  
M. Prístavková ◽  
M. Bošanský
Keyword(s):  
Failure Mode ◽  
Fire Safety ◽  
Occupational Safety ◽  
Fire Risk ◽  
Acceptable Level ◽  
Post Harvest ◽  
Before And After

The objective of this work is the evaluation of threats in the field of safety, fire safety, quality and environment in the post-harvest treatment of grain, with an emphasis put on pre-cleaning and drying of grain. The paper describes the technology of pre-cleaning and drying of grain. Risks for individual machines were evaluated using a failure mode and effects analysis (FMEA), which is used to evaluate the threats in terms of fire risk, occupational safety, the effect of machine on the quality of final product, and effect on the environment. We have proposed measures and solutions to eliminate or minimise the consequences of threats. Risk rates are evaluated before and after measures adopted. It can be stated based on the results that risk was successfully reduced to an acceptable level after adopting measures.

Study on corrosion effect of high-performance concrete under the action of sulfate and chlorine

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940054 ◽  
Author(s):  
Rongrong Yin ◽  
Jie Hu ◽  
Yu Liu ◽  
Qing Wu ◽  
Chenchen Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Growth Stage ◽  
High Performance Concrete ◽  
Slow Growth ◽  
Concrete Strength ◽  
Corrosion Damage ◽  
Chloride Salt ◽  
Single Action ◽  
Two Stages

The thickness of corroded concrete layer and the compressive strength of prisms under the action of sulfate and chloride salt were investigated by ultrasonic test and compression test, respectively. The results show that under the single action of sulfate, the strength of concrete experienced two stages: a slow growth stage and a rapid descent stage. Correspondingly, under the combined action of sulfate and chloride, the concrete strength experienced another two stages: a slow growth stage and a slow degradation stage. The existence of chloride inhibited the corrosion damage of concrete in a certain extent. It was found that higher concentration of chlorine salt would lead to a stronger inhibition effect. A good consistency was observed among corrosion layer thickness, compressive strength and X-ray diffraction results. The inhabitation of chloride to the sulfate corrosion of concrete was proved.

scholarly journals Fat Tail Analysis on S&P 100 Stocks-before and after US President Election

2020 ◽  
Vol 19 (3) ◽  
pp. 79-88
Author(s):  
Sandeep Thakur
Keyword(s):  
Heavy Tails ◽  
Economic Condition ◽  
Donald Trump ◽  
Fat Tail ◽  
Us Economy ◽  
The Us ◽  
Before And After ◽  
Key Factor ◽  
Climate And Health ◽  
Tail Analysis

The main aim of this paper is to determine whether the volatility in the stocks can be created by events like the US Election and whether it leads to Fat Tail in the stocks. Fat Tail analysis is a key factor in determining volatility and has been used in the economy as well as in many other fields like climate and health. Log return has been used to determine the Fat Tail. To make the work more reliable, two Presidential election periods, that of Barack Obama and Donald Trump is selected and is compared for volatility and Fat Tail. For this study, stocks from the S&P 100 are selected and observed. The results show that the US economy is not at all driven by who comes in power and when but rather by the present economic condition. Stocks showing heavy tails during the Obama presidency are primarily because the economy was under Sub Prime Crisis too.

scholarly journals Experimental study on the effect of concrete strength and corrosion level on bond between steel bar and concrete

2021 ◽  
Vol 72 (4) ◽  
pp. 498-509
Author(s):  
Vuong Doan Dinh Thien ◽  
Hung Nguyen Thanh ◽  
Hung Nguyen Dinh
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Concrete Strength ◽  
Concrete Block ◽  
Bond Stress ◽  
Concrete Compressive Strength ◽  
Pull Out ◽  
Steel Bar ◽  
Stress Degradation ◽  
Slip Displacement

Corrosion of the steel reinforcement bars reduces the area of the steel bar and the bond stress between the steel bars and around concrete that decreases the capacity of concrete structures. In this study, the bond stress between steel bar with a diameter of 12mm and concrete was examined with the effect of different corrosion levels and different concrete grades. A steel bar was inserted in a concrete block with a size of 20×20×20cm. The compressive strength of concrete was 25.6MPa, 35.1MPa, and 44.1MPa. These specimens were soaked into solution NaCl 3.5% to accelerate the corrosion process with different corrosion levels in the length of 60mm. The pull-out test was conducted. Results showed that the bond strength of the corroded steel bar was higher than that predicted from CEB-FIP. Slip displacement and the range of slip displacement at the bond strength were reduced when the concrete compressive strength was increased. The rate of bond stress degradation occurred faster with the increment of the corrosion level when the concrete compressive strength was increased.

scholarly journals Design of experiments for verification of computational life prediction methods

2019 ◽  
Vol 18 (3) ◽  
pp. 143-154
Author(s):  
O. V. Samsonova ◽  
K. V. Fetisov ◽  
I. V. Karpman ◽  
I. V. Burtseva
Keyword(s):  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Turbine Engines ◽  
Prediction Methods ◽  
Gas Turbine Engines ◽  
Loading Conditions ◽  
Load History ◽  
Strain Behavior ◽  
Before And After ◽  
Two Stages

The failure of heavily loaded rotating parts of aviation gas turbine engines may bring about dangerous consequences. The life of such parts is limited with the use of computational and experimental methods. Computational life prediction methods that are used without carrying out life-cycle tests of engine parts or assemblies should be substantiated experimentally. The best option for verifying the computational methods is to use the results of cyclic tests of model disks. These tests make it possible to reproduce loading conditions and surface conditions that correspond to those of real disks, and the data on the load history and material properties make it possible to simulate stress-strain behavior of disks under test conditions by calculation. This paper shows the process of planning such tests. It is assumed that the tests will be carried out in two stages - before and after the initiation of a low-cycle fatigue crack. A number of criteria are formulated that the geometry of model disks and their loading conditions are to satisfy. Based on these criteria, model disks were designed and the conditions for their testing were selected.

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