Seismic Strengthening of Column-Pier-Cap Connections

1998 ◽  
Vol 1624 (1) ◽  
pp. 93-100 ◽  
Author(s):  
David H. Sanders ◽  
M. Saiid Saiidi ◽  
Troy Martin
Keyword(s):  
Energy Dissipation ◽  
Seismic Risk ◽  
Plastic Hinge ◽  
Joint Damage ◽  
Highway Bridges ◽  
Joint Region ◽  
Steel Jacket ◽  
Energy Dissipation Capacity ◽  
The 1960S ◽  
Strengthening Technique

Many bridges constructed in the 1960s in regions of high seismic risk have column–pier-cap connections with inadequate column bar development and no shear reinforcement in the joint region. The study described in this paper focuses on highway bridges built on Interstate 80 in the Reno, Nevada, area during the 1960s. Two 0.4-scale specimens representing the essential features of the column–pier-cap connections in these bridges were constructed and tested. One test showed that the asbuilt specimen had little energy dissipation capacity and failed at less than 1 percent drift. A second specimen was used to test a potential strengthening technique. The technique included increasing pier-cap depth, adding a concrete bolster to the joint, and placing a steel jacket around the column. After strengthening, a plastic hinge formed in the column, the joint damage was minimized, and the energy dissipation capacity increased by a factor of 5.

scholarly journals Seismic Performance of Various Piles Considering Soil–Pile Interaction under Lateral Cycle Loads for Integral Abutment Jointless Bridges (IAJBs)

2020 ◽  
Vol 10 (10) ◽  
pp. 3406
Author(s):  
Fuyun Huang ◽  
Yulin Shan ◽  
Ahad Javanmardi ◽  
Xiaoye Luo ◽  
Baochun Chen
Keyword(s):  
Energy Dissipation ◽  
Plastic Hinge ◽  
Reinforcement Ratio ◽  
Effective Length ◽  
Deformation Capacity ◽  
Integral Abutment ◽  
Concrete Pile ◽  
Jointless Bridges ◽  
Pile Interaction ◽  
Energy Dissipation Capacity

The flexural pile foundation is used in integral abutment jointless bridges (IAJBs) in practical engineering to effectively dissipate the horizontal reciprocating deformation induced by the ambient temperature or earthquake loadings. Various types of flexural piles including the H-shaped steel pile (HP), prestressed concrete pile (PC), prestressed high-strength concrete pile (PHC) as well as the reinforcement concrete pile (RC) have been implemented in IAJBs. However, there is a lack of comprehensive studies on the flexural deformation and seismic performances of these piles. In order to investigate and compare their mechanical behaviors and seismic performances, a low-cycle pseudo-static test on several different types of piles was carried out. The test results indicated that the plastic hinge location of piles moved to a deeper pile depth with the increase of reinforcement ratio, buried pile depth and prestressing level, which led to better pile–soil interaction. The crack resistance of a concrete pile was improved as the reinforcement ratio and prestressing level increased. Moreover, the rectangular pile had a better soil–pile interaction and energy dissipation capacity than the circular pile. The inflection point of the pile deformation shifted deeper as reinforcement ratio, buried pile depth and prestressing level increased, which improved the effective length and horizontal deformation capacity of piles. The H-shaped steel pile showed a better elastic-plastic deformation capacity, ductility and energy dissipation capacity as compared to the concrete pile. Moreover, the pile having a higher bearing ratio sustained larger lateral loads whereas the surrounding soil was subjected to higher loads. Finally, new seismic design criteria of three-stage seismic fortification and five damage level for the concrete piles of IAJBs were proposed.

scholarly journals Cyclic Responses of Two-Side-Connected Precast-Reinforced Concrete Infill Panels with Different Slit Types

Buildings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 16
Author(s):  
Guohua Sun ◽  
Fei Li ◽  
Qiyou Zhou
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Failure Mode ◽  
Damping Ratio ◽  
Concrete Strength ◽  
Plastic Hinge ◽  
Cyclic Behavior ◽  
Lateral Stiffness ◽  
Lateral Strength ◽  
Energy Dissipation Capacity

This study aimed to study the cyclic behavior of two-side-connected precast-reinforced concrete infill panel (RCIP). A total of four RCIP specimens with different slit types and height-to-span ratios modeled at a one-third scale were tested subjected to cyclic lateral loads. The failure mode, hysteretic behavior, lateral strength, stiffness degradation, ductility, and energy dissipation capacity of each RCIP specimen were determined and analyzed. The specimens experienced a similar damage process, which involved concrete cracking, steel rebar yielding, concrete crushing, and plastic hinge formation. All the specimens showed pinched hysteretic curves, resulting in a small energy dissipation capacity and a maximum equivalent viscous damping ratio lower than 0.2. The specimens with penetrated slits experienced ductile failure, in which flexural hinges developed at both slit wall ends. The application of penetrated slits decreased the initial stiffness and lateral load-bearing capacity of the RC panel but increased the deformation capacity, the average ultimate drift ratios ranged from 1.41% to 1.99%, and the lowest average ductility ratio reached 2.48. The specimens with high-strength concrete resulted in a small slip no more than 1 mm between the RC panel and steel beam, and the channel shear connectors ensured that the RC infill panel developed a reliable assembly with the surrounding steel components. However, specimens with concealed vertical slits (CVSs) and concealed hollow slits (CHSs) achieved significantly higher lateral stiffness and lateral strength values. Generally, the specimens exhibited two-stage mechanical features. The concrete in the CVSs and CHSs was crushed, and flexural plastic hinges developed at both ends of the slit walls during the second stage. With increasing concrete strength, the initial lateral stiffness and lateral strength values of the RCIP specimens increased. With an increasing height-to-span ratio, the lateral stiffness and strength of the RC panels with slits decreased, but the failure mode remained unchanged.

Experimental investigation into ultra-low cycle fatigue behavior of composite members in spatial grid structures

2020 ◽  
Vol 23 (12) ◽  
pp. 2514-2528
Author(s):  
Xiayun Song ◽  
Haiwang Li ◽  
Jie Zhang
Keyword(s):  
Energy Dissipation ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Plastic Hinge ◽  
Cumulative Damage ◽  
Cycle Fatigue ◽  
Plastic Hinges ◽  
Energy Dissipation Capacity ◽  
Spatial Grid

As earthquakes tend to cause ultra-low cycle fatigue failure of spatial grid structures in composite members and joints, this study sets out to test six groups of specimen comprising steel pipes and bolt sphere joints and analyzes the influence of joints and loading systems on failure modes, hysteretic behavior, skeleton curves, stiffness degradation, energy dissipation capacity, and the formation and development of plastic hinges. Results showed that the instability of the specimen in compressive loading led to the occurrence of denting and the formation of plastic hinges. Cracks originated in dented area, and ultra-low cycle fatigue fractures occurred in a dozen cycles. Plastic hinge was located in the middle area of the pipe, and the energy dissipation capacity was limited owing to the confined plastic hinge length. As the joint bending stiffness increased, so did the length of the plastic hinge, the degree of the dent, and the cumulative damage. Early fractures and a reduction in total energy consumption also occurred. Furthermore, a function related to the cumulative damage and macroscopic deformation that can evaluate the damage of the members in spatial grid structures was also established.

Experiment Research on Mechanical Behavior for Latticed Concrete-Filled Steel Tubular Tower with Three Limbs

2011 ◽  
Vol 368-373 ◽  
pp. 58-61 ◽  
Author(s):  
Bin Li ◽  
Zhong Zhou Han ◽  
Chun Yan Gao
Keyword(s):  
Energy Dissipation ◽  
Plastic Hinge ◽  
Failure Process ◽  
Static Test ◽  
Wind Turbine Tower ◽  
Unstable Failure ◽  
Tower Structure ◽  
Energy Dissipation Capacity ◽  
Tower Model ◽  
Hysteretic Properties

Based on the 1.5MW cone cylinder wind turbine tower widely used at present, latticed concrete-filled steel tubular (CFST) tower with three limbs was designed. The stress mechanism and failure process, hysteretic properties, bearing capacity and energy dissipation capacity were studied by quasi-static test on the tower model. The results indicate that the hysteretic loops of the latticed CFST tower with three limbs present asymmetrical plump “spindle” and there is no obvious "pinch" phenomenon, which shows good seismic performance and energy dissipation capacity; and that owing to the latticed CFST tower with three limbs is asymmetric along the centroidal axis perpendicular to loading direction, plastic hinge finally appeared in the tower column foot which beared the largest force, the bottom web members were buckled and occur unstable failure. From the analysis it can be seen that the latticed CFST tower structure with three limbs has value of further research and promotion.

The Finite Element Analyses for Beam Strengthen-Bolt Spliced Connection for Steel Moment Frame

2012 ◽  
Vol 446-449 ◽  
pp. 3390-3393
Author(s):  
Yan Xia Zhang ◽  
Quan Xi Ye ◽  
Lu Yao Wang
Keyword(s):  
Finite Element ◽  
Energy Dissipation ◽  
Plastic Hinge ◽  
Finite Element Analyses ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Plastic Rotation ◽  
Energy Dissipation Capacity ◽  
Beam Strengthening

Two types of beam Strengthening-Bolt spliced connection were analyzed by using ABAQUS. The results showed that Beam Strengthen- Bolt Spliced Connection can effectively make the relocation of the plastic hinge. The plastic rotation and energy dissipation capacity of beam Strengthen-Bolt spliced connection exhibited excellent.

scholarly journals Experimental and Numerical Analysis of the Mechanical Properties of a Pretreated Shape Memory Alloy Wire in a Self-Centering Steel Brace

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 80
Author(s):  
Bo Zhang ◽  
Sizhi Zeng ◽  
Fenghua Tang ◽  
Shujun Hu ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Effective Elastic Modulus ◽  
Maximum Energy ◽  
Numerical Results ◽  
Energy Dissipation Capacity

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

scholarly journals Experimental/Numerical Evaluation of Steel Trapezoidal Corrugated Infill Panels with an Opening

2021 ◽  
Vol 11 (7) ◽  
pp. 3275
Author(s):  
Majid Yaseri Gilvaee ◽  
Massood Mofid
Keyword(s):  
Energy Dissipation ◽  
Ultimate Strength ◽  
Steel Plate ◽  
Shear Walls ◽  
Experimental Results ◽  
Structural Performance ◽  
Initial Stiffness ◽  
Infill Panels ◽  
Energy Dissipation Capacity ◽  
Ductility Ratio

This paper investigates the influence of an opening in the infill steel plate on the behavior of steel trapezoidal corrugated infill panels. Two specimens of steel trapezoidal corrugated shear walls were constructed and tested under cyclic loading. One specimen had a single rectangular opening, while the other one had two rectangular openings. In addition, the percentage of opening in both specimens was 18%. The initial stiffness, ultimate strength, ductility ratio and energy dissipation capacity of the two tested specimens are compared to a specimen without opening. The experimental results indicate that the existence of an opening has the greatest effect on the initial stiffness of the corrugated steel infill panels. In addition, the experimental results reveal that the structural performance of the specimen with two openings is improved in some areas compared to the specimen with one opening. To that end, the energy dissipation capacity of the specimen with two openings is obtained larger than the specimen with one opening. Furthermore, a number of numerical analyses were performed. The numerical results show that with increasing the thickness of the infill plate or using stiffeners around the opening, the ultimate strength of a corrugated steel infill panel with an opening can be equal to or even more than the ultimate strength of that panel without an opening.

scholarly journals Estimation of Additional Equivalent Damping Ratio of the Damped Structure Based on Energy Dissipation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xiuyan Hu ◽  
Qingjun Chen ◽  
Dagen Weng ◽  
Ruifu Zhang ◽  
Xiaosong Ren
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Theoretical Concept ◽  
Estimation Methods ◽  
External Excitation ◽  
Single Degree Of Freedom ◽  
Equivalent Damping ◽  
Seismic Motion ◽  
Practical Engineering ◽  
Energy Dissipation Capacity

In the design of damped structures, the additional equivalent damping ratio (EDR) is an important factor in the evaluation of the energy dissipation effect. However, previous additional EDR estimation methods are complicated and not easy to be applied in practical engineering. Therefore, in this study, a method based on energy dissipation is developed to simplify the estimation of the additional EDR. First, an energy governing equation is established to calculate the structural energy dissipation. By means of dynamic analysis, the ratio of the energy consumed by dampers to that consumed by structural inherent damping is obtained under external excitation. Because the energy dissipation capacity of the installed dampers is reflected by the additional EDR, the abovementioned ratio can be used to estimate the additional EDR of the damped structure. Energy dissipation varies with time, which indicates that the ratio is related to the duration of ground motion. Hence, the energy dissipation during the most intensive period in the entire seismic motion duration is used to calculate the additional EDR. Accordingly, the procedure of the proposed method is presented. The feasibility of this method is verified by using a single-degree-of-freedom system. Then, a benchmark structure with dampers is adopted to illustrate the usefulness of this method in practical engineering applications. In conclusion, the proposed method is not only explicit in the theoretical concept and convenient in application but also reflects the time-varying characteristic of additional EDR, which possesses the value in practical engineering.

A combined experimental and numerical analysis on the seismic behavior of short reinforced concrete columns with different structural sizes and axial compression ratios

2017 ◽  
Vol 27 (9) ◽  
pp. 1416-1447 ◽  
Author(s):  
Liu Jin ◽  
Shuai Zhang ◽  
Dong Li ◽  
Haibin Xu ◽  
Xiuli Du ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Axial Compression ◽  
Seismic Behavior ◽  
Load Capacity ◽  
Concrete Columns ◽  
Simulation Method ◽  
Reinforced Concrete Columns ◽  
Mesoscopic Simulation ◽  
Energy Dissipation Capacity

The results of an experimental program on eight short reinforced concrete columns having different structural sizes and axial compression ratios subjected to monotonic/cyclic lateral loading were reported. A 3D mesoscopic simulation method for the analysis of mechanical properties of reinforced concrete members was established, and then it was utilized as an important supplement and extension of the traditional experimental method. Lots of numerical trials, based on the restricted experimental results and the proposed 3D mesoscopic simulation method, were carried out to sufficiently evaluate the seismic performances of short reinforced concrete columns with different structural sizes and axial compression ratios. The test results indicate that (1) the failure pattern of reinforced concrete columns can be significantly affected by the shear-span ratio; (2) increasing the axial compression ratio could improve the load capacity of the reinforced concrete column, but the deformation capacity would be restricted and the failure mode would be more brittle, consequently the energy dissipation capacity could be deteriorated; and (3) the load capacity, the displacement ductility, and the energy dissipation capacity of the short reinforced concrete columns all exhibit clear size effect, namely, the size effect could significantly affect the seismic behavior of reinforced concrete columns.

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