Limit of axial force ratio and requirement for stirrups of RC columns with special shape

2007 ◽  
Vol 1 (2) ◽  
pp. 176-181
Author(s):  
Yiqun Wang ◽  
Yidong Xu ◽  
Yanjing Zhao ◽  
Yunxia Chen
Keyword(s):  
Axial Force ◽  
Special Shape ◽  
Rc Columns ◽  
Force Ratio

Axial Performance of Various Strengthening Methods Applied on Full-Scale Rectangular RC Columns

2011 ◽  
Vol 82 ◽  
pp. 618-623 ◽  
Author(s):  
Pei Ching Chen ◽  
Min Lang Lin ◽  
Yin Han Wu
Keyword(s):  
Axial Force ◽  
Full Scale ◽  
Reinforcement Ratio ◽  
The Other ◽  
Transverse Reinforcement ◽  
Rc Columns ◽  
Different Shapes ◽  
Adhesive Anchors ◽  
Cfrp Wrapping ◽  
Better Than

The performance of RC columns subjected to axial force is relative to the confinement. CFRP wrapping, a generally adopted retrofit method, was proved not to effectively provide confining force due to the bulging effect on the column face. Therefore, this paper is focused on the performance of the retrofitted full-scale rectangular RC columns using different retrofit schemes including the proposed CFRP wrapping conjugated with CFRP anchors method. A total of eleven rectangular RC columns with low transverse reinforcement ratio were constructed. Among them, one was tested as benchmark; one was purposely constructed with larger transverse reinforcement ratio; five were retrofitted by using CFRP wrapping and CFRP anchors; and the other four were retrofitted by using different shapes of steel jacketing alone or with adhesive anchors. All the specimens were subjected to monotonic incremental axial force until failure occurred. Experimental results demonstrated that the ductility of the specimens retrofitted by using CFRP wrapping with CFRP anchors was significantly improved compared with those retrofitted by using only CFRP wrapping. On the other hand, the specimen with octagonal steel jacketing performed better than all other specimens not only on ductility but also on strength. Finally, a novel numerical model considering the contribution of the retrofit material will be proposed and validated in the future.

Optimization on the Performance of a Precision Flank-Locking Locknut Considering the Machining and Operational Parameters

2017 ◽  
Vol 35 (1) ◽  
pp. 41-49 ◽  
Author(s):  
C. M. Chen ◽  
C. Y. Lee
Keyword(s):  
Taguchi Method ◽  
Axial Force ◽  
Machining Process ◽  
Average Error ◽  
Optimized Design ◽  
Control Parameters ◽  
Operational Parameters ◽  
Machining Processes ◽  
Tightening Torque ◽  
Force Ratio

AbstractIn this study, the anti-loosening characteristics of a precision flank-locking locknut fabricated under various machining processes and tested in different dynamic environments were investigated. The control parameters considered include the tightening torque and thread pitch of the set screw, machining process on the end plane of locknut, and vibration amplitude and frequency of dynamic loading in service, etc. Their sensitivities on the axial force ratio and anti-loosening ratio of the locknut were evaluated using Taguchi method. It was found that the pretension of locknut, the tightening torque and the pitch of set screw, and the machining process of the nut's end plane were the significant control parameters for the anti-loosening performance of the locknut. Moreover, the results of experimental measurements were employed in the regression fit on the performance of the locknut. The regression model was able to predict the anti-loosening ratio with 4.42% average error comparing with the measurements. Furthermore, the optimized design of the locknut through the Taguchi method was able to increase the axial force ratio and anti-loosening ratio by 20.4% and 16.8%, respectively, comparing with standard locknut.

Axial Strain of Reinforced Concrete Columns

2010 ◽  
Vol 163-167 ◽  
pp. 1858-1861 ◽  
Author(s):  
Jong Wook Park ◽  
Sang A Cha ◽  
Ji Eun Kang ◽  
Mohamad Mansour ◽  
Jung Yoon Lee
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Axial Force ◽  
Axial Strain ◽  
Plastic Hinge ◽  
Rc Columns ◽  
Reversed Cyclic Loading ◽  
Depth Ratio ◽  
Short Span ◽  
Reversed Cyclic

The reinforced concrete members are designed to fail in flexural member to behave ductilely. Also the failure doesn’t impose on columns but beams. But according to the plastic collapse mechanism, the plastic hinge potentially developed at the bottom of the RC column near the base of the structure after flexural yielding. These columns are generally dominated by shear which led to sudden failure in post yielding region because of its relatively short span-to-depth ratio, so special care is needed. The deformability of column with short span-to-depth ratio is small compared with larger span-to-depth ratio column under reversed cyclic loading. Therefore the design of these kinds of RC columns necessitates the prediction of both the shear strength after flexural yielding and corresponding ductility of such members. Ten RC columns with varying axial force ratio and shear reinforcement ratio were tested under monotonic and reversed cyclic loading. The most affectable factor to column behavior was the axial force. The result indicates that concrete contribution to shear resistance in the plastic hinge region and axial strain were decreased as axial force.

The Influence of Corrosion on the Anti-Loosening Performance of a Precision Locknut Subjected to Rotation and Periodic Impact

2019 ◽  
Vol 36 (3) ◽  
pp. 295-303 ◽  
Author(s):  
C. M. Chen ◽  
H. L. Chang ◽  
C. Y. Lee
Keyword(s):  
Machine Tool ◽  
Real Time ◽  
Axial Force ◽  
Contact Surface ◽  
Nacl Solution ◽  
Transverse Impact ◽  
Dynamic Impact ◽  
Force Ratio ◽  
Design And Manufacturing ◽  
Impact Tester

ABSTRACTThe influence of combined corrosion and vibration to the anti-loosening performance of a precision locknut used in a machine tool is investigated. Firstly, the locknut was submerged in 5% NaCl solution according to ASTM B895 standard for corrosion testing. The locknuts, after submerged in 1-hr, 2-hr and 4-hr periods, respectively, were then installed on the rotating spindle in a vertical dynamic impact tester for performing anti-loosening test. The initial installed pretension was 9800 N and the spindle was rotating in a constant speed of 1000 rpm. Turmogrease Li 802 EP lubricant was used on the contact surface between spindle thread and locknut. The set screws on the locknut were tightened sequentially and evenly in three-stage of torque: 1.96 N-m, 3.92 N-m and 5.88 N-m. Its real-time pretension variation with the periodic transverse impact and its final loosening torque were measured. Accordingly, the axial force ratio and anti-loosening torque ratio were calculated and discussed. It was found that corrosion treatment had similar influence on both the axial force ratio and the anti-loosening torque ratio. More corrosion on the locknut with longer submersion in NaCl solution deteriorated its anti-loosening characteristics. The result could serve as the reference for evaluating the fastening performance of precision locknut and guide the design and manufacturing for the application improvement.

Effects of Outrigger Truss Systems on Collapse Initiation Times of High-Rise Towers Exposed to Fire

2011 ◽  
Vol 82 ◽  
pp. 344-349
Author(s):  
Daigoro Isobe ◽  
Thi Thai Thanh Le
Keyword(s):  
Axial Force ◽  
Joint Strength ◽  
Structural Parameters ◽  
Progressive Collapse ◽  
Strength Ratio ◽  
Initiation Time ◽  
Structural Vulnerability ◽  
High Rise ◽  
Load Paths ◽  
Force Ratio

In this paper, progressive collapse analyses were performed on a 30-story, seven-span tower that was exposed to fire. The Adaptively Shifted Integration (ASI)-Gauss technique was used to demonstrate the effects of fire patterns and structural parameters on collapse initiation time: the duration from the beginning of the fire until collapse initiation. Specifically, an outrigger truss system was placed on the roof of a model, and the influence of the system on the structural vulnerability of the tower was verified. The structural parameters that were varied in the analyses included the axial force ratio, the member joint strength ratio and the member strength ratio of the outrigger trusses to the strength of the beams on the first floor. From the numerical results, it is confirmed that collapse initiation times are significantly affected by the member joint strength ratio if the axial force ratio is small (floor loads are low) on the condition that the fire pattern is nearly symmetrical, and the load paths to and from the outrigger truss system are sufficiently protected.

Experimental Study on Seismic Behavior of Steel-Plate Reinforced Concrete Shear Wall with Rectangular CFST Columns

2012 ◽  
Vol 446-449 ◽  
pp. 370-377
Author(s):  
Jian Wei Zhang ◽  
Wan Lin Cao ◽  
Hong Ying Dong
Keyword(s):  
Reinforced Concrete ◽  
Axial Force ◽  
Seismic Behavior ◽  
Steel Plate ◽  
Shear Wall ◽  
Steel Tube ◽  
Force Ratio ◽  
Hysteretic Characteristics ◽  
Cfst Columns ◽  
Composite Shear

The steel-plate reinforced concrete shear wall with rectangular concrete filled steel tube (CFST) columns is a new kind of composite shear wall. In order to ascertain its seismic behavior and failure mechanism, four 1/5 scale specimens with the same shear span ratio 1.5, different thickness of the steel-plate and different axial force ratio, were tested under horizontal cyclic loading. The thickness of steel-plate in the walls is 2mm, 4mm, 4mm and 6mm, respectively. Based on the experiment, the load-bearing capacity, hysteretic characteristics, ductility, stiffness degradation, energy dissipation capacity and failure mode of the specimens were contrastively analyzed. And the effect of the ratio of height to sectional thickness of steel-plate and the value changes of axial force ratio on seismic behavior of the new shear wall was also analyzed. The result shows that the steel-plate reinforced concrete shear wall with rectangular CFST columns has good seismic performance and important engineering value.

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