Seismic performance of semi-tenon joints reinforced by steel angle in traditional timber buildings

2020 ◽  
Vol 23 (11) ◽  
pp. 2318-2332
Author(s):  
Jianyang Xue ◽  
Guoqi Ren ◽  
Jiaheng Zhang ◽  
Dan Xu
Keyword(s):  
Seismic Performance ◽  
Numerical Study ◽  
Bending Moment ◽  
Flexural Capacity ◽  
Response Characteristics ◽  
Steel Angle ◽  
Rotation Stiffness ◽  
Joint Connection ◽  
Reversed Loading ◽  
Steel Angles

This article presents an experimental and numerical study on seismic performance of semi-tenon joints reinforced by steel angle in traditional timber buildings. Five specimens with two different reinforced connections and one unreinforced connection subjected to low-cyclic reversed loading on the bending moment are examined. The unreinforced connection consists of left and right beams inserted into the column that has been used in setting up the mortise before assembly. The first type of reinforced connection is formed by bottom steel angles bolted to the column and jointed to the beam by means of bolts. The second type of reinforced connection is made up of top and bottom steel angles bolted to the column and connected to the beam relying on vertical and transverse bolts. Moreover, two reinforcement techniques aimed at enhancing the seismic performance of semi-tenon joints are investigated, including the change of steel angle limb length and the variation of steel angle limb thickness. The test setup, joint connection, reinforced conditions, and material properties are introduced through detailed account of the experimental results and observations. The key behavioral patterns are identified from the experiments and the main response characteristics such as hysteresis, stiffness, flexural capacity, energy dissipation, and the failure mechanism. This article demonstrates that the steel angle can enhance the flexural capacity of the semi-tenon joints significantly. Besides, the use of greater limb thickness steel angle is shown to be an effective detail for adequately increasing the flexural capacity and rotation stiffness of the joints. Finite element simulations of experiments are also conducted, together with a detailed description of the modeling methods, so as to gain further insight into the influence of various factors on the behavior of joints.

scholarly journals Seismic Performance of Deposit Slopes With Underlying Bedrock Before and After Reinforcement by Stabilising Piles

2021 ◽  
Author(s):  
Zhiliang Sun ◽  
Kong Lingwei ◽  
Bai Wei ◽  
Wang Yong
Keyword(s):  
Seismic Performance ◽  
Seismic Waves ◽  
Bending Moment ◽  
Resultant Force ◽  
Shaking Table ◽  
Slope Instability ◽  
Dynamic Responses ◽  
Seismic Excitation ◽  
Ground Acceleration ◽  
Response Characteristics

Abstract The seismic performance of stabilising piles used to reinforce underlying bedrock in a deposit slope is a complex soil-structure interaction problem, on which there is limited design guidance on the optimum use of a single row of rock-socketed piles to reinforce such slopes. Two centrifuge shaking-table model tests at a geometric scale of 1:50 were conducted to ascertain the dynamic responses of the underlying bedrock deposit slopes without and with the use of stabilising piles during an earthquake. Multi-stage seismic waves with various peak accelerations were applied from the bottom of each model. Under seismic excitation, the differences in the response accelerations between the deposit and bedrock increase significantly with the increase in amplitude of the input seismic waves. The two are prone to uncoordinated movement, which leads to slope instability. Setting stabilising piles reduces the crest settlement and angular deformation and changes the natural frequency of the slope crest. The presence of the rock-socketed stabilising piles can bridge the uncoordinated movement of the bedrock and the overlying deposit to some extent. According to the mobilised pile bending moment, shear force, lateral pile-soil load distribution, and pile displacement, the dynamic response characteristics of stabilising piles under continuous multi-level seismic excitation were analysed. The resultant force arising from a distributed load increment on the piles caused by an earthquake is mainly concentrated in the upper part (the point of action of the resultant force is 1.54m below the slope surface). With increases in the peak ground acceleration (PGA) of the input motion, the resistance of the bedrock in front of the stabilising piles increases; moreover, with the increase of PGA, the peak resistance under the bedrock surface of the stabilising piles gradually moves downwards. This finding indicates that the strong seismic motion significantly changes the embedded working state of the stabilising pile.

Experimental and numerical study on seismic performance of steel reinforced recycled concrete frame structure under low-cyclic reversed loading

2018 ◽  
Vol 21 (12) ◽  
pp. 1895-1910 ◽  
Author(s):  
Jianyang Xue ◽  
Xin Zhang ◽  
Rui Ren ◽  
Lei Zhai ◽  
Linlin Ma
Keyword(s):  
Energy Dissipation ◽  
Seismic Performance ◽  
Numerical Study ◽  
Concrete Strength ◽  
Hysteresis Loops ◽  
High Energy ◽  
Recycled Concrete ◽  
Frame Structure ◽  
Concrete Frame ◽  
Reversed Loading

This article mainly focused on the seismic performance of steel reinforced recycled concrete frame structure under low-cyclic reversed loading. To evaluate seismic performance of steel reinforced recycled concrete frame structure, a two-span three-storied steel reinforced recycled concrete frame was conducted at civil engineering laboratory of Xi’an University of Architecture and Technology. Experimental and numerical studies were implemented to investigate the crack status, failure modes, hysteresis loops, skeleton curves, energy dissipation capacity, load–displacement curves, P-Δ effect, and the influence of recycled concrete strength under low-cyclic reversed loading. Results indicate that the steel reinforced recycled concrete frame structure has good seismic behavior during test, and the spindle-shaped hysteresis loops illustrate that the frame has relatively high energy dissipation capacities. The design of steel reinforced recycled concrete frame satisfied the requirements of strong column weak beam, strong shear weak bending, and strong joint weak components. Finally, the simulated results obtained by OpenSees software agree well with the test, which verify the rationality and reliability of the proposed model. The conclusions of this article will be helpful for the design of steel reinforced recycled concrete structures in seismic regions.

Tunnel performance during the Puebla-Mexico 19 September 2017 earthquake

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 288-313
Author(s):  
Juan M Mayoral ◽  
Gilberto Mosqueda ◽  
Daniel De La Rosa ◽  
Mauricio Alcaraz
Keyword(s):  
Mexico City ◽  
Seismic Performance ◽  
Urban Areas ◽  
Numerical Study ◽  
Three Dimensional ◽  
Frequency Content ◽  
Seismic Performance Evaluation ◽  
Ground Deformations ◽  
Under Construction ◽  
Observed Damage

Seismic performance of tunnels during earthquakes in densely populated areas requires assessing complex interactions with existing infrastructure such as bridges, urban overpasses, and metro stations, including low- to medium-rise buildings. This article presents the numerical study of an instrumented tunnel, currently under construction on stiff soils, located in the western part of Mexico City, during the Puebla-Mexico 19 September 2017 earthquake. Three-dimensional finite difference models were developed using the software FLAC3D. Initially, the static response of the tunnel was evaluated accounting for the excavation technique. Then, the seismic performance evaluation of the tunnel was carried out, computing ground deformations and factors of safety, considering soil nonlinearities. Good agreement was observed between predicted and observed damage during post-event site observations. Once the soundness of the numerical model was established, a numerical study was undertaken to investigate the effect of frequency content in tunnel-induced ground motion incoherence for tunnels built in cemented stiff soils. A series of strong ground motions recorded during normal and subduction events were used in the simulations, considering a return period of 250 years, as recommended in the Mexico City building code. From the results, it was concluded that the tunnel presence leads to important frequency content modification in the tunnel surroundings which can affect low- to mid-rise stiff structures located nearby. This important finding must be taken into account when assessing the seismic risk in highly populated urban areas, such as Mexico City.

Performance of parking steel column damaged by fire

2019 ◽  
Vol 10 (2) ◽  
pp. 138-154
Author(s):  
Farshid Masoumi ◽  
Ebrahim Farajpourbonab
Keyword(s):  
Cyclic Loading ◽  
Seismic Performance ◽  
Numerical Study ◽  
Mechanical Analysis ◽  
Content Type ◽  
Steel Columns ◽  
Fire Engineering ◽  
Steel Column ◽  
Concrete Coating ◽  
Fire Loading

Purpose The primary purpose of this research was to expand the knowledge base regarding the behavior of steel columns during exposure to fire. This paper presents the numerical study of the effect of heat on the performance of parking steel column in a seven-story steel building under cyclic loading. Design/methodology/approach In this research, the forces and deformations developed during a fire are estimated by using detailed 3D finite-element models. The analyses are in the form of a coupled thermo-mechanical analysis in two types of loading: concurrent loading (fire and cyclic loading) and non-concurrent loading (first fire and then cyclically), and the analyses have been conducted in both states of the fire loading with cooling and without cooling using the ABAQUS software. Further, it was investigated whether, during the fire loading, the specimen was protected by a 3-cm-thick concrete coating and how much it changes the seismic performance. After verification of the specimen with the experimental test results, the column model was investigated under different loading conditions. Findings The result of analyses indicates that the effect of thermal damage on the performance of steel columns, when cooling is happening late, is more than the state in which cooling occurs immediately after the fire. In this paper, thermal–seismic performance of parking steel columns has been specified and the effect of the fire damage has been investigated for the protected steel by concrete coating and to the non-protected steel, under both cooling and non-cooling states. Originality/value This study led to recommendations based on the findings and suggestions for additional work to support performance-based fire engineering. It is clear that predicting force and deformation on steel column during fire is complex and it is affected by many variables. Here in this paper, those variables are examined and proper results have been achieved.

Numerical study of the seismic performance of a double-hinge steel frame joint

2021 ◽  
Vol 187 ◽  
pp. 106963
Author(s):  
Jian-peng Wei ◽  
Li-min Tian ◽  
Yang Guo ◽  
Hui-yun Qiao ◽  
Yu Bao ◽  
...  
Keyword(s):  
Seismic Performance ◽  
Numerical Study ◽  
Steel Frame

Test and Numerical Study on the Seismic Performance of A Cable Restrainer for Girder Bridges

2019 ◽  
Author(s):  
Yitong Gu ◽  
Wancheng Yuan ◽  
Xinzhi Dang
Keyword(s):  
Seismic Performance ◽  
Numerical Study ◽  
Design Method ◽  
Lateral Displacement ◽  
Static Test ◽  
Girder Bridges ◽  
Continuous Girder Bridge ◽  
Service Conditions ◽  
Girder Bridge ◽  
Parametric Analyses

<p>In China, most of the support systems applied by short/medium span bridges are elastomeric pad bearings (EPBs). This type of support system has no reliable connections between bearings and girders as well as bearings and piers, which will cause structural damages due to large lateral displacement of bearings under earthquakes. The restrainers used currently could restrict the deformation of bridges under normal service conditions and could only restrict unidirectional displacement. Considering the disadvantages of these restrainers, a new restrainer called Connected Cable Restrainer (CCR), which can be used in short/medium span bridges supported by EPBs, is developed in this paper. The design principle, basic configuration, isolation mechanism and the design method of CCR are introduced. A pseudo static test to study the seismic performance of CCR is conducted. Seismic responses of a 3-span continuous girder bridge with CCR are simulated using OpenSees platform and parametric analyses of the two main parameters, lateral restraining displacement and restraining stiffness, are also carried out. Results show that the deformation of bridges under normal service conditions would not be restrained using CCR and the displacement responses can be mitigated effectively by using CCR through parameter optimization.</p>

Experimental study on the seismic performance of traditional timber mortise-tenon joints with different looseness under low-cyclic reversed loading

2018 ◽  
Vol 22 (6) ◽  
pp. 1312-1328 ◽  
Author(s):  
Jianyang Xue ◽  
Rui Guo ◽  
Liangjie Qi ◽  
Dan Xu
Keyword(s):  
Energy Dissipation ◽  
Seismic Performance ◽  
Failure Modes ◽  
Artificial Defect ◽  
Reversed Loading ◽  
Energy Dissipation Capacity ◽  
Strength And Stiffness ◽  
Seismic Behaviors ◽  
Damage Type ◽  
Better Than

The majority of existing ancient timber structures have different degrees of damage. The looseness of mortise-tenon joints is a kind of typical damage type. In order to study the influence of looseness on the seismic performance of mortise-tenon joints, six through-tenon joints and six dovetail-tenon joints with scale 1:3.2 were fabricated according to the requirements of the engineering fabrication method of Chinese Qing Dynasty. Each type of joints consisted of one intact joint and five artificial loose joints, and the artificial defect was made to simulate looseness by cutting the tenon sectional dimension. Based on experiments of two types of joints under low-cyclic reversed loading, the seismic behaviors of joints such as failure modes, hysteretic loops and skeleton curves, strength and stiffness degradation, and energy dissipation capacity were studied. Moreover, the comparative analyses of seismic performance between two types of joints were carried out. The variation tendency of seismic behaviors of two types of joints has similarities, and there are some differences due to their different structural styles. The results indicate that squeeze deformation between tenon and mortise of two types of joints occurred. The shape of hysteretic loops of two types of joints is reverse-Z-shape, and the pinching effect of hysteretic loops becomes more obvious with the increase in looseness, among which of through-tenon joints is more obvious than that of dovetail-tenon joints. The carrying capacity, stiffness, and energy dissipation capacity of loose joints are significantly lower than that of the intact one, and the energy dissipation capacity of dovetail-tenon joints is better than that of through-tenon joints. The rotation angles of two types of joints can reach 0.12 rad, and the loose joints still have great deformation capacity.

scholarly journals Synthesis of numerical methods for the design of segmental tunnel lining

2019 ◽  
Vol 295 ◽  
pp. 03008
Author(s):  
Rim Trad ◽  
Hussein Mroueh ◽  
Hanbing Bian ◽  
Fabrice Cormery
Keyword(s):  
Numerical Study ◽  
Direct Method ◽  
Bending Moment ◽  
Experimental Methods ◽  
Tunnel Lining ◽  
Practical Case ◽  
Lining Structure ◽  
Water Conveyance ◽  
Internal Forces ◽  
Water Conveyance Tunnel

This paper presents a numerical study that aims to compare the behavior of the segmental tunnel lining using the direct, indirect and experimental methods. This model is based on a practical case applied in university of Tongji: a project of water conveyance tunnel. A reduction in the bending moment and increasing of the displacement in the tunnel lining is showed in numerical results, when taking into account the effect of the joints. It has been shown that the number of joints in the tunnel-lining structure highly affects the results in terms internal forces and displacements. Furthermore, the internal forces obtained by the continuous method are high compared to the other methods when the effects on segmental joints on tunnel lining behaviour are usually considered. Additionally, the bending moment of the direct method with behaviour of rotation spring linear and experimental method is comparable.

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