Lateral Resisting Experiment of Prestressed-Tube Bolted Connection for Post-and-Beam Timber Construction

2013 ◽  
Vol 778 ◽  
pp. 631-638 ◽  
Author(s):  
Min Juan He ◽  
Yi Zhao ◽  
Ren Le Ma
Keyword(s):  
Damping Ratio ◽  
Hysteresis Curve ◽  
Lateral Stiffness ◽  
Loading Test ◽  
Bolted Connection ◽  
Equivalent Viscous Damping ◽  
Timber Construction ◽  
Moment Resisting ◽  
Good Potential ◽  
Timber Connections

Connections are key elements and the weak points for timber structures. The most commonly used bolted timber connections with slotted in steel plate have low lateral stiffness and poor ductility in post-and-beam construction. This paper introduces the prestressed-tube bolted connection to alleviate this problem. To evaluate its lateral resisting performance, the failure mode, strength, lateral stiffness, ductility, hysteresis curve and equivalent viscous damping ratio of the ordinary and improved connections, as determined by the monotonic and reversed cyclic loading test, are compared. The results demonstrate that the lateral stiffness of the prestressed-tube bolted connection has been significantly improved, and its ductility is also better than the normal bolted connection with no decrease in the ultimate moment resisting capacity. It is believed that the semi-rigid prestressed-tube bolted connection, as an alternative to current bolted solutions, may provide reasonable lateral stiffness and has good potential for use in post-beam timber construction.

scholarly journals Study on Interaction of RC Pile-Soil with High Reinforcement Ratio of Integral Abutment Bridges under Quasi-Static Test

2022 ◽  
Vol 2148 (1) ◽  
pp. 012029
Author(s):  
Ying Luo ◽  
Fuyun Huang ◽  
Zhifu Chen ◽  
Xinghua Liu ◽  
Zhengfeng Liu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Damping Ratio ◽  
Effective Interaction ◽  
Reinforcement Ratio ◽  
Hysteresis Curve ◽  
Deformation Capacity ◽  
Test Results ◽  
Integral Abutment ◽  
Equivalent Viscous Damping ◽  
Skeleton Curve

Abstract In order to improve the ability of the reinforcement concrete (RC) pile foundation of integral abutment to absorb the horizontal reciprocating deformation under the action of temperature or earthquake, a pseudo-static low cycle test on interaction of pile-soil with high reinforcement ratio was carried out. The failure location, hysteresis curve, skeleton curve and horizontal deformation of three piles with different reinforcement ratios were compared. The test results show that, with the increase of the reinforcement ratio, the crack of the RC pile develops along the pile body to the depth, and the pile body failure area and the position where the maximum bending moment moves down, the crack resistance of the pile body is improved, and the effective interaction pile length increases; The test results also show that the hysteresis curve of the model pile becomes fuller with the increase of the reinforcement ratio, compared with the RCP-1 specimen with the lowest reinforcement ratio, the equivalent viscous damping ratio of the RCP-3 specimen is increased by 31.6%, and the energy dissipation capacity is improved. In addition, with the increase of the reinforcement ratio, the bearing capacity and deformation capacity of model piles are greatly improved. Compared with RCP-1 specimen, the ultimate bearing capacity of RCP-3 specimen increased by 150%, and the corresponding ultimate displacement increased by 153%. Increasing reinforcement ratio can significantly improve the mechanical properties and deformation capacity of RC pile.

scholarly journals Experimental investigations into the mechanical performance of glulam dowel-type connections with either bolts or screws as fasteners

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Zheng Li ◽  
Wei Feng ◽  
Jiajia Ou ◽  
Feng Liang ◽  
Minjuan He
Keyword(s):  
Failure Modes ◽  
Mechanical Performance ◽  
Damping Ratio ◽  
Experimental Investigations ◽  
Bolted Connections ◽  
Equivalent Viscous Damping ◽  
Moment Resisting ◽  
Loading Tests ◽  
Cyclic Loading Tests ◽  
Ductility Ratio

AbstractDowel-type connections are the most common connections in glulam structures. Bolts are often used as fasteners for dowel-type connections. However, the clearance between the bolts and the pre-drilled bolt holes leads to low rotational stiffness and insufficient moment-resisting capacity. To achieve better mechanical performance, screws can be used as alternative fasteners for dowel-type connections. In this paper, monotonic and cyclic loading tests were conducted on glulam dowel-type connections with either bolts or screws as fasteners. The failure modes, moment-resisting capacity, ductility ratio, stiffness degradation, and equivalent viscous damping ratio of the specimens were analyzed and reported. Results showed that compared with traditional bolted connections, the screwed connections had larger moment-resisting capacity and better ductility. The hysteretic loops of the screwed connections were plumper, and the pinching effect was gentler compared to those of traditional bolted connections.

scholarly journals EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF PEC COMPOSITE COLUMN-STEEL BEAM FRAME WITH WELDED T-STUB STRENGTHENED CONNECTIONS

2021 ◽  
Keyword(s):  
Energy Dissipation ◽  
Failure Mode ◽  
Seismic Performance ◽  
Damping Ratio ◽  
Plastic Hinge ◽  
Frame Structure ◽  
Steel Beam ◽  
Lateral Stiffness ◽  
Equivalent Viscous Damping ◽  
Composite Frame

Seismic performance of innovative Partially Encased Composite (PEC) column-steel beam composite frame was investigated, where the connection was strengthened by the welded T-stub. A ½ scale, two-storey, and one bay composite frame specimen was designed and fabricated for the quasi-static test. Through the experimental observation and measurements, the seismic performance were evaluated, including hysteretic characteristic, lateral stiffness, seismic energy dissipation, and ductility. The plastic damage evolution process and ductile failure mode were clarified. The results indicated that the welded T-stud strengthened connection enhanced the integrity of the frame and led to higher seismic strength and larger lateral stiffness. The plastic hinge was observed away from the beam end due to the welded T-stud and the specimen exhibited an approximately completed hysteretic loop. Without significant decreasing of the ultimate bearing capacity, its overall drift, ductility efficient and equivalent viscous damping ratio were 3.63% (push) / 4.07% (pull), 3.21 (push) / 3.70 (pull) and 0.261 respectively. The proposed structure possesses sound deformation, ductility, and energy-dissipation capacity with the desired plastic failure mode induced by the plastic hinges formed in all beam sections near the T-stud end and column section at the bottom, successively. It was demonstrated an ideal ductile energy-dissipation mode of the frame structure.

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.

An Adaptive Loading Test on Collapse Mechanism Formation of Multi-Story Steel Frames Subjected to Uncertain Lateral Load Pattern

2007 ◽  
Vol 345-346 ◽  
pp. 1169-1172
Author(s):  
Kenichi Ohi ◽  
Jae Hyouk Choi
Keyword(s):  
Limit State ◽  
Lateral Force ◽  
Collapse Mechanism ◽  
Loading Test ◽  
Design Point ◽  
Steel Moment Resisting Frames ◽  
Random Combination ◽  
Moment Resisting ◽  
Earthquake Load ◽  
Load Pattern

An adaptive loading system is developed to examine a design point of multi-story steel test frames subjected to uncertain load pattern. Lateral loads are given as a random combination of basic load patterns, and the system drives a test frame to the most likely failure situation. Two-story steel moment resisting frames are tested considering a failure mechanism formation of plastic collapse as a tentative limit state. A random 2-dof lateral force is given by a random combination of two basic load patterns, which are arranged to represent elastic earthquake load effects. Hybrid design point search or adaptive loading tests on the 2-story frame are performed, and the detected likely failure mechanisms are compared with the results of pseudo-dynamic response tests to deterministic excitations.

scholarly journals Energy-Based Design Criterion of Dissipative Bracing Systems for Seismic Retrofit of Frame Structures

2018 ◽  
Author(s):  
Gloria Terenzi
Keyword(s):  
Damping Ratio ◽  
Dissipative System ◽  
Design Criterion ◽  
Frame Structures ◽  
Element Analysis ◽  
Equivalent Viscous Damping ◽  
Linear Behaviour ◽  
Energy Based Design ◽  
Equivalent Viscous Damping Ratio ◽  
Reduction Factors

Direct sizing criteria represent useful tools in the design of dissipative bracing systems for the advanced seismic protection of existing frame structures, especially when incorporated dampers feature a markedly non-linear behaviour. An energy-based procedure is proposed herein to this aim, focusing attention on systems including fluid viscous devices. The procedure starts by assuming prefixed reduction factors of the most critical response parameters in current conditions, which are evaluated by means of a conventional elastic finite element analysis. Simple formulas relating the reduction factors to the equivalent viscous damping ratio of the dissipaters, ξeq, are proposed. These formulas allow calculating the ξeq values that guarantee the achievement of target factors. Finally, the energy dissipation capacity of the devices is deduced from ξeq, finalizing their sizing process. A detailed description of the procedure is presented in the article, by distinguishing the cases where the prevailing structural deficiencies are represented by poor strength of the constituting members, from the cases having excessive horizontal displacements. A demonstrative application to the retrofit design of a reinforced concrete gym building is then offered to explicate the steps of the sizing criterion in practice, as well as to evaluate the enhancement of seismic response capacities generated by the installation of the dissipative system.

scholarly journals Finding the Key: Designing Timber Connections for CLT Panels

2021 ◽  
Author(s):  
◽  
Gabriella Joyce
Keyword(s):  
Large Scale ◽  
Computational Design ◽  
Digital Fabrication ◽  
Timber Construction ◽  
Structural Capacity ◽  
Connection System ◽  
Digital Modelling ◽  
Thermal Bridging ◽  
Timber Connections ◽  
Mass Timber

<p>In a climate where standard methods of construction are being challenged, developments in engineered timbers are allowing mass timber construction to be explored as a sustainable alternative to traditional building methods. Cross- laminated timber (CLT) is at the forefront of this evolution and, with the advancement in computational design and digital fabrication tools, there lies an opportunity to redefine standard construction. This project explores how digital modelling and advance digital fabrication can be combined to generate a connection system for CLT panels.  The advantages of CLT and mass timber construction are numerous and range from environmental and aesthetic benefits to site safety and cost reduction benefits. There are, however, issues that remain surrounding the connections between CLT panels. Steurer (2006, p.136) stated that, “Progress in engineered timber construction is directly related to developments in connector technology.” This thesis creates connections inspired by traditional Japanese joinery that have been adapted to be used for the panel construction of CLT structures. Using CLT offcuts as a primary connection material, the system not only reduces waste but also mitigates thermal bridging and lowers the number of connection points whilst increasing the ease of building and fabrication.  The connections are first considered at a detail scale. They use the literature review and case studies as a base for design before being tested using digitally fabricated prototypes. These prototypes are evaluated against a framework created in line with the aforementioned criteria. Within this framework, the connections are analysed against existing connection systems as well as previous designs to establish a successful system. The connections are then evaluated within the context of a building scale and considers large-scale fabrication and on- site assembly whilst continuing to focus on the reduction of waste. This research found that the simplicity of the connections is key to a successful system as this allows for faster and cheaper fabrication and installation. However, there is still further research needed surrounding large-scale fabrication and the structural capacity of timber connection systems.</p>

Improving Damping Properties of Railway Ballast by Addition of Tire-Derived Aggregate

2019 ◽  
Vol 2673 (5) ◽  
pp. 299-307 ◽  
Author(s):  
Weimin Song ◽  
Baoshan Huang ◽  
Xiang Shu ◽  
Hao Wu ◽  
Hongren Gong ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Damping Ratio ◽  
Shear Stiffness ◽  
Damping Properties ◽  
Railway Ballast ◽  
Loading Test ◽  
Interface Shear ◽  
Peak Shear Stress ◽  
Dilation Effect ◽  
Tire Derived Aggregate

The damping properties of railway ballast are critical to the safe operation of trains. This study aimed to improve the damping properties of railway ballast through the addition of tire-derived aggregate (TDA) and to evaluate the effect of TDA on other properties of ballast. The damping property and other mechanical properties of ballast mixed with different contents of TDA were tested utilizing a large direct shear test (DST) under static and cyclic loading conditions. The cyclic loading test was performed in accordance with ASTM D 7499, from which the resilient interface shear stiffness and damping ratio were obtained. The results showed that TDA significantly increased the damping ratio of railway ballast, but decreased the resilient interface shear stiffness. The stress-strain behavior of the ballast-TDA mixes was obtained from the static loading test, showing that TDA significantly decreased the peak shear stress and the dilation effect. According to the Mohr-Coulomb failure criterion, TDA also decreased the cohesion strength and the internal friction angle of the ballast. Based on the test results from this study, 5% rubber is recommended for use in railway ballast.

scholarly journals Seismic Material Properties of Reinforced Concrete and Steel Casing Composite Concrete in Elevated Pile-Group Foundation

2015 ◽  
Vol 22 (s1) ◽  
pp. 141-148 ◽  
Author(s):  
Mi Zhou ◽  
Wancheng Yuan ◽  
Yue Zhang
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Damping Ratio ◽  
Pile Group ◽  
Ocean Engineering ◽  
Static Loads ◽  
Equivalent Viscous Damping ◽  
Static Tests ◽  
Equivalent Viscous Damping Ratio ◽  
Positive Effect

Abstract The paper focuses on the material mechanics properties of reinforced concrete and steel casing composite concrete under pseudo-static loads and their application in structure. Although elevated pile-group foundation is widely used in bridge, port and ocean engineering, the seismic performance of this type of foundation still need further study. Four scale-specimens of the elevated pile-group foundation were manufactured by these two kinds of concrete and seismic performance characteristic of each specimen were compared. Meanwhile, the special soil box was designed and built to consider soil-pile-superstructure interaction. According to the test result, the peak strength of strengthening specimens is about 1.77 times of the others and the ultimate displacement is 1.66 times of the RC specimens. Additionally, the dissipated hysteric energy capability of strengthening specimens is more than 2.15 times of the others as the equivalent viscous damping ratio is reduced by 50%. The pinching effect of first two specimens is more obvious than latter two specimens and the hysteretic loops of reinforced specimens are more plumpness. The pseudo-static tests also provided the data to quantitatively assessment the positive effect of steel casing composite concrete in aseismatic design of bridge.

Energy Dissipation of Damper Rings for Thin-Walled Gears

2019 ◽  
Author(s):  
Zichao Li ◽  
Yanrong Wang ◽  
Xianghua Jiang ◽  
Hang Ye ◽  
Weichao Yang
Keyword(s):  
Energy Dissipation ◽  
Contact Surface ◽  
Strain Difference ◽  
Damping Ratio ◽  
Harmonic Balance Method ◽  
Axial Direction ◽  
Relative Displacement ◽  
Axial Displacement ◽  
Hysteresis Curve ◽  
Thin Walled

Abstract When the gear generates a nodal mode shape vibration, there are two directions of possible relative displacement between the corresponding points on the contact surface of the damper ring and the damper groove, which are circumferential direction and axial direction respectively. In this paper, the relative displacement of the damper ring and the damper groove are considered in two directions, and the calculation method of energy dissipation is proposed. When the nodal vibration occurs in the gear, due to the existence of the strain difference between the damper ring and the damper groove on the contact surface, circumferential slip of partial area would occur. The energy dissipation in one vibration cycle is accurately determined by analytical solution. Since the aviation gears are mostly thin-walled structures, the axial displacement is large when resonance occurs. Based on the discrete damper ring model which considers interaction between every segment of the ring, the first-order harmonic balance method is used to calculate the axial displacement of the damper ring under the given gear rim amplitude. And then the hysteresis curve area of each discrete segment on the contact surface is summed to obtain energy dissipation in one vibration cycle. In this paper, based on the energy method, the damping effect of the damper ring is predicted. The damping ratio curve obtained by energy dissipation in two directions is compared and analyzed. The occurrence conditions of the two directions of possible relative displacement and the influence of the damper ring parameters on both situations are summarized.

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