Seismic behaviors of precast assembled bridge columns connected with prestressed threaded steel bar: Experimental test and hysteretic model

2020 ◽  
Vol 23 (9) ◽  
pp. 1975-1988
Author(s):  
Qifang Xie ◽  
Xudong Zhao ◽  
Xiaofei Yao ◽  
Wenming Hao ◽  
Fangzheng Hu
Keyword(s):  
Seismic Performance ◽  
Service Performance ◽  
Bridge Pier ◽  
Hysteretic Model ◽  
Initial Stiffness ◽  
Good Service ◽  
Static Test ◽  
Steel Bar ◽  
Steel Bars ◽  
Socket Connection

Three 1/10-scale bridge pier specimens were tested under quasi-static test. The specimens included two precast specimens (PC1 and PC2) and one cast-in-place reference specimen. The two precast bridge pier specimens were connected with prestressing threaded steel bar and steel flange at the connection between precast pier column and the foundation, and non-socket assembly scheme and socket assembly scheme are adopted, respectively. They were tested to verify the seismic performance of prefabricated piers connected by prestressed threaded steel bars and steel flanges and study which assembly scheme is better for non-socketed and socketed piers. The results show that the prefabricated pier with the combination of the prestressed threaded steel bars and steel flange has higher cracking load and smaller residual displacement, which indicates that it has good service performance and good self-resetting ability. Compared with the non-socket assembly scheme, the socket assembly scheme is superior due to its higher ductility, higher overall initial stiffness, and higher energy dissipation capacity. Therefore, the prefabricated assembled pier with the socket connection scheme of the combination of the prestressed threaded steel bars and steel flange has good service performance and seismic performance. After that, a hysteretic model for the precast assembled columns was proposed, which has a good agreement with the test results.

Performance of a transfer beam with hybrid reinforcement of CFRP bars and steel bars under reversed cyclic loading

2017 ◽  
Vol 24 (4) ◽  
pp. 621-630
Author(s):  
Jin Chen ◽  
Shiyong Jiang ◽  
Xiangrong Zeng ◽  
Ling Zhou ◽  
Tao Sun ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Seismic Performance ◽  
Flexural Property ◽  
Static Test ◽  
Reversed Cyclic Loading ◽  
Vertical Loading ◽  
Steel Bars ◽  
Hysteretic Characteristics ◽  
Hybrid Reinforcement ◽  
Reversed Cyclic

AbstractHybrid carbon fiber reinforced plastic (CFRP) and steel bar reinforcement concrete were applied in a transfer beam. Three specimens (ZHL-2, ZHL-3, and ZHL-4) corresponded to different forms of reinforcement, reinforcement ratio, and reinforced root number, respectively. The pseudo static test of the three specimens was carried out under the condition of vertical loading and horizontal reversed cyclic loading. The flexural property and failure mode of the transfer beams were demonstrated. Further, the ductility, energy dissipation capability, hysteretic characteristics, structural yield mechanism, and failure mechanism were also studied. The exploration of these factors was aimed to study the bearing capacity and seismic performance of the transfer beam with hybrid CFRP and steel bars. The test results show that if both the upper and lower longitudinal reinforcements were replaced by CFRP bars with a symmetrical reinforcement, the mechanical property and deformation performance would be superior. The performance would be better than the reinforcements with single upper and lower replacement by CFRP bars. Both the upper and lower longitudinal bars of the transfer beam should be replaced by CFRP bars with a symmetrical form of reinforcement. The ductility performance would be better for the transfer beam with the hybrid reinforcement of CFRP bars and steel bars. It showed a seismic performance. The transfer beam with the hybrid reinforcement of CFRP bars and steel bars could meet the design requirements for the ductile frame “strong column, weak beam and strong node.”

Pseudo-static test research on EBIMFCW with different shear-span ratio

2019 ◽  
Vol 11 (3) ◽  
pp. 427-442
Author(s):  
Sheng-cai Li ◽  
Guo Lin
Keyword(s):  
Seismic Performance ◽  
Design Method ◽  
Initial Stiffness ◽  
Test Parameter ◽  
Content Type ◽  
Static Test ◽  
Shear Span ◽  
Loading Tests ◽  
Composite Walls ◽  
Bending Failure

Purpose The purpose of this paper is to study the seismic performance of the energy-saving block and invisible multi-ribbed frame composite walls (EBIMFCW), changing the shear-span ratio as the test parameter, the low-cycle reciprocating loading tests of six 1/2 scale wall models were carried out. Design/methodology/approach The test design method and analysis are used for the seismic performance of the EBIMFCW. Findings With the increase of shear-span ratio: the walls tend to occur bending failure even more, the initial stiffness of the wall decreases, the overall ductility of the wall is improved and the walls tend to occur bending failure. Originality/value The previous studies do not involve the seismic performance of EBIMFCW under different shear-span ratios. Therefore, the paper studies the hysteresis behavior, ductility, stiffness degradation and energy dissipation performance of EBIMFCW under different shear-span ratios.

scholarly journals Design and Experimental Study on Shock-Absorbing Steel Bar with Limit Function for Bridges

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Zhaoguang Li ◽  
Ri Gao ◽  
Wei Jia
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Hysteresis Curve ◽  
Limit Function ◽  
Viscous Damping ◽  
Initial Stiffness ◽  
Equivalent Viscous Damping ◽  
Steel Bar ◽  
Steel Bars ◽  
Equivalent Viscous Damping Ratio

The existing research on shock-absorbing steel bars is only limited to simply supported beam bridge. In order to expand the application of shock-absorbing steel bars to other fields, this paper develops a novel shock-absorbing steel bar with limit function, and it is suitable for continuous beam bridges. The structure and working mechanism of the shock-absorbing steel bar are analyzed. Three sets of specimens of the shock-absorbing steel bar are fabricated and then repeatedly loaded by the designed quasistatic loading device, in order to investigate their seismic performance parameters, including hysteresis curve, skeleton curve, and initial stiffness and equivalent viscous damping ratio. The results show that when the displacement of the specimen exceeds the initial gap, it enters the stage of energy dissipation and has a stable hysteresis curve and good fatigue resistance. Besides, the shock-absorbing device has a high initial stiffness and can provide stable bearing capacity after yielding. The equivalent viscous damping ratio reflects that the designed shock-absorbing steel bar has good energy dissipation capacity.

scholarly journals Experimental Investigation into the Seismic Performance of Prefabricated Reinforced Masonry Shear Walls with Vertical Joint Connections

2021 ◽  
Vol 11 (10) ◽  
pp. 4421
Author(s):  
Zhiming Zhang ◽  
Fenglai Wang
Keyword(s):  
Seismic Performance ◽  
Cross Sections ◽  
Shear Walls ◽  
Construction Method ◽  
Shear Capacity ◽  
Initial Stiffness ◽  
Equivalent Viscous Damping ◽  
Displacement Ductility ◽  
Reinforced Masonry ◽  
Cracking Performance

In this study, four single-story reinforced masonry shear walls (RMSWs) (two prefabricated and two cast-in-place) under reversed cyclic loading were tested to evaluate their seismic performance. The aim of the study was to evaluate the shear behavior of RMSWs with flanges at the wall ends as well as the effect of construction method. The test results showed that all specimens had a similar failure mode with diagonal cracking. However, the crack distribution was strongly influenced by the construction method. The lateral capacity of the prefabricated walls was 12% and 27% higher than that of the corresponding cast-in-place walls with respect to the rectangular and T-shaped cross sections. The prefabricated walls showed better post-cracking performance than did the cast-in-place wall. The secant stiffness of all the walls decreased rapidly to approximately 63% of the initial stiffness when the first major diagonal crack was observed. The idealized equivalent elastic-plastic system showed that the prefabricated walls had a greater displacement ductility of 3.2–4.8 than that of the cast-in-place walls with a displacement ductility value of 2.3–2.7. This proved that the vertical joints in prefabricated RMSWs enhanced the seismic performance of walls in shear capacity and ductility. In addition, the equivalent viscous damping of the specimens ranged from 0.13 to 0.26 for prefabricated and cast-in-place walls, respectively.

scholarly journals Cyclic Tests and Numerical Analyses on Bolt-Connected Precast Reinforced Concrete Deep Beams

2021 ◽  
Vol 11 (12) ◽  
pp. 5356
Author(s):  
Jing Li ◽  
Lizhong Jiang ◽  
Hong Zheng ◽  
Liqiang Jiang ◽  
Lingyu Zhou
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Seismic Performance ◽  
High Strength ◽  
Length Ratio ◽  
Frame Structures ◽  
Initial Stiffness ◽  
Frame Buildings ◽  
Parametric Analyses ◽  
Bending Failure

A bolt-connected precast reinforced concrete deep beam (RDB) is proposed as a lateral resisting component that can be used in frame structures to resist seismic loads. RDB can be installed in the steel frame by connecting to the frame beam with only high-strength bolts, which is different from the commonly used cast-in-place RC walls. Two 1/3 scaled specimens with different height-to-length ratios were tested to obtain their seismic performance. The finite element method is used to model the seismic behavior of the test specimens, and parametric analyses are conducted to study the effect on the height-to-length ratio, the strength of the concrete and the height-to-thickness ratio of RDBs. The experimental and numerical results show that the RDB with a low height-to-length ratio exhibited a shear–bending failure mode, while the RDB with a high height-to-length ratio failed with a shear-dominated failure mode. By comparing the RDB with a height-to-length ratio of 2.0, the ultimate capacity, initial stiffness and ductility of the RDB with a height-to-length ratio of 0.75 increased by 277%, 429% and 141%, respectively. It was found that the seismic performance of frame structures could be effectively adjusted by changing the height-to-length ratio and length-to-thickness of the RDB. The RDB is a desirable lateral-resisting component for existing and new frame buildings.

Evaluation on the Addition of Inhibitor and Surface Treatment to Corrosion Behavior of the Reinforced Steel Bar Embedded in Mortar Specimen

2017 ◽  
Vol 744 ◽  
pp. 114-120
Author(s):  
Kyung Man Moon ◽  
Sung Yul Lee ◽  
Jae Hyun Jeong ◽  
Myeong Hoon Lee
Keyword(s):  
Current Density ◽  
Test Specimen ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Corrosion Properties ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Steel Bars ◽  
Reinforced Steel ◽  
One Year

In this study, seven types of mortar test specimens were manufactured with parameters, that is, the surface of the reinforced steel bar was treated with hot dip galvanizing (Zn) and the surface of the test specimen was coated with underwater paint, and four types of inhibitors (DAW, MCI, DCI, and Silcon) were added in mortars respectively. And, the seven types of mortar test specimens were immersed in seawater for 4 years. The corrosion properties of the reinforced steel bars embedded in mortar test specimens were investigated using electrochemical methods. The corrosion potentials of the test specimens with painting on the surface of the specimen and Zn coating on the surface of the steel bar exhibited the noblest and lowest values respectively after one year, however, after 4 years, the specimens of underwater painting and of addition of Silcon inhibitor indicated the noblest and lowest values of corrosion potentials respectively. Furthermore, the painting specimen exhibited the smallest values of corrosion probability as welll as of the corrosion current density, while, addition of MCI inhibitor showed the highest values of both corrosion probability and corrosion current density. Moreover, the painting specimen showed the smallest value of neutralization degree among all the specimens, and the largest value of neutralization degree was observed at the specimen of natural condition (no adding of inhibitor, no painting and no Zn coating). As a result, it is considered that the addition of inhibitors, coating with hot dip galvanizing (Zn), and painting on the surface have the effects not only to inhibit the neutralization degree but also to increase the corrosion resistance of the embedded steel bar.

scholarly journals USING THE SERVQUAL MODEL TO ASSESSMALL SERVICE QUALITY AND CUSTOMER SATISFACTION

2017 ◽  
Vol 14 (1) ◽  
pp. 82
Author(s):  
Larissa Maria Argollo de Arruda Falcão ◽  
Taciana De Barros Jerônimo ◽  
Fagner José Coutinho de Melo ◽  
Joas Tomaz de Aquino ◽  
Denise Dumke de Medeiros
Keyword(s):  
Point Of View ◽  
Service Performance ◽  
Level Of Service ◽  
Future Research ◽  
Good Service ◽  
Administrative Services ◽  
Service Companies ◽  
Basic Performance

This  paper  use  SERVQUAL measure  for  assessingthe  quality  of  the  administrative  services  in  a  large  mall,located in Brazil,  seen from the point of view of the currentservice  providers.  A questionnaire  was  used  to  interview 68service companies, and 5 CEO mall of this case of study. Twofactors were compared: the expectations and perceptions of theservice  providers,  the  comparison  enabled  the  strengths  andweaknesses of the quality perceived of the services offered bythe  mall  were  undertaken  as  a  case  study. Understand whatfeatures  and  level  of  service  must  have  in  order  to  meetconsumer needs, against on how consumers perceive the actualmall  performance  in  the  context  of  what  they  expected  to ensuring  good  service  to  classify  into  three  categories  offactors:  Basic,  Performance  and  Excitement.The  findings  ofthis study may prompt future research to create a new tool tohelp those managers and service companies in the process ofmaking decisions aimed at improving the strategic relationshipwith retail companies and thus to improve the quality of themall  services.  One  contribution  of  this  study  is  the  simpleproposed model used to understanding how quality processesaffect each organizational dimension of service performance.

scholarly journals A High Precision Quality Inspection System for Steel Bars Based on Machine Vision

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2732 ◽  
Author(s):  
Xinman Zhang ◽  
Jiayu Zhang ◽  
Mei Ma ◽  
Zhiqi Chen ◽  
Shuangling Yue ◽  
...  
Keyword(s):  
Machine Vision ◽  
High Precision ◽  
Absolute Error ◽  
Detection Methods ◽  
Inspection System ◽  
Quality Inspection ◽  
Construction Site ◽  
High Definition ◽  
Steel Bar ◽  
Steel Bars

Steel bars play an important role in modern construction projects and their quality enormously affects the safety of buildings. It is urgent to detect whether steel bars meet the specifications or not. However, the existing manual detection methods are costly, slow and offer poor precision. In order to solve these problems, a high precision quality inspection system for steel bars based on machine vision is developed. We propose two algorithms: the sub-pixel boundary location method (SPBLM) and fast stitch method (FSM). A total of five sensors, including a CMOS, a level sensor, a proximity switch, a voltage sensor, and a current sensor have been used to detect the device conditions and capture image or video. The device could capture abundant and high-definition images and video taken by a uniform and stable smartphone at the construction site. Then data could be processed in real-time on a smartphone. Furthermore, the detection results, including steel bar diameter, spacing, and quantity would be given by a practical APP. The system has a rather high accuracy (as low as 0.04 mm (absolute error) and 0.002% (relative error) of calculating diameter and spacing; zero error in counting numbers of steel bars) when doing inspection tasks, and three parameters can be detected at the same time. None of these features are available in existing systems and the device and method can be widely used to steel bar quality inspection at the construction site.

scholarly journals Research on Compression Behavior of Square Thin-Walled CFST Columns with Steel-Bar Stiffeners

2018 ◽  
Vol 8 (9) ◽  
pp. 1602 ◽  
Author(s):  
Zhao Yang ◽  
Chengxiang Xu
Keyword(s):  
Bearing Capacity ◽  
Local Buckling ◽  
Steel Tube ◽  
Steel Tubes ◽  
Compression Behavior ◽  
Steel Bar ◽  
Steel Bars ◽  
Thin Walled ◽  
Structural Measure ◽  
Cfst Columns

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto the tubes. Static-loading tests were conducted to study the compression behavior of square thin-walled CFST columns with steel bar stiffeners placed inside or outside the tube. The effect and feasibility of steel bar stiffeners were studied through the analysis of failure mode, load–displacement relationship, ultimate load, ductility, and local buckling. Different setting methods of steel bars were compared as well. The results showed that steel-bar stiffeners proposed in this paper can be effective in delaying local buckling as well as increasing the bearing capacity of the columns, but will decrease the ductility of the columns. In order to obtain a higher bearing capacity of columns, steel bars with low stiffness should be placed inside and steel bars with high stiffness should be placed outside of the steel tubes. The study is helpful in providing reference to the popularization and application of this new structural measure to avoid or delay the local buckling of thin-walled CFST columns.

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