scholarly journals Experimental and Numerical Investigation on Bearing Capacity of Circumferential Joint of New Spatial Steel Tubular Grid Arch in Mined Tunnel

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2065
Author(s):  
Yuan Song ◽  
Mingli Huang ◽  
Xudong Zhang ◽  
Zhaoping Li ◽  
Xingxin Peng
Keyword(s):  
Bearing Capacity ◽  
Cross Sections ◽  
Failure Modes ◽  
High Strength ◽  
Development Stage ◽  
Surrounding Rock ◽  
Whole Process ◽  
Bending Capacity ◽  
Tubular Grid ◽  
Strength And Stiffness

Under the circumstance of soft fractured surrounding rock with high geo-stress, the support technology of tunnel has become a major challenge. Traditional I-shaped steel and bar lattice girder, which cross-sections are often designed to be left-right symmetrical, may have insufficient strength and stiffness. Based on the concept of symmetry, a new support technology of spatial steel tubular grid (SSTG) arch is designed with high strength and large stiffness. In order to clarify the mechanical properties and failure mechanism of SSTG arch used as primary support, through laboratory and numerical experiments, this paper carries out the bending tests for the circumferential joint of SSTG arch components combined with the excavation tunnel project of Panyu Square Station in Guangzhou, and the analyses of the ultimate bearing capacity, deflection displacement, failure modes, and stress–strain evolution laws of joint components are conducted in detail. The results show that during the whole process of loading, the arch components have experienced elastic growth stage, plastic development stage, and final failure stage. The average ultimate bending capacity of SSTG arches is 340.5 kN·m, and the joint opening is 13.9 mm. The joint form of high-strength bolt + rigid flange plate proposed in the paper has reasonable stress state and high safety redundancy, which can bear the load of surrounding rock effectively, and ensure the safety in tunnel construction. The research results could provide a theoretical basis for the design and application of SSTG arch support in related projects.

Hysteretic Behavior of Composite Vertical Connection Structures used in Prefabricated Shear Wall Systems

2020 ◽  
Vol 20 (06) ◽  
pp. 2040007
Author(s):  
Limeng Zhu ◽  
Haipeng Yan ◽  
Po-Chien Hsiao ◽  
Jianhua Zhang
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
High Strength Steel ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Shear Walls ◽  
High Strength ◽  
Shear Wall ◽  
Hysteretic Behavior ◽  
Design Standards

An innovative composite vertical connecting structure (CVC) with capacity carrying and energy-dissipating ability is proposed in this study, which could be used in prefabricated composite shear wall structural systems to enhance the resilience and seismic performance of structural system. The CVC structure is mainly composed of three parts, including the connecting zone, the capacity bearing zone characterized by high strength and elastic deforming ability, and the energy-dissipating zone assembled by replaceable metal dampers. The low-yield strength steel and high-strength steel are used, respectively, for the metal dampers in the energy-dissipating zone and the concrete-filled high-strength steel tubes in the bearing capacity zone to enhance the energy dissipation and self-centering abilities of CVC structures. The working mechanism is analyzed and validated through finite element models built in ABAQUS. The hysteretic behavior is simulated to evaluate their performance. First, the metal dampers are designed. The theoretical and finite elemental parametric analysis are carried out. According to the simulation results, the “Z-shaped” metal dampers exhibit better energy-dissipating ability than the rectangular shape, in which the “Z-shaped” metal dampers with 45∘ show the best performance. Simultaneously, the results of the models calculated by the finite element method and theoretical analysis work very well with each other. Furthermore, seven FE models of shear walls with CVC structures are designed. Monotonic and cyclic loading simulations are conducted. The failure modes and comprehensive mechanical performance are investigated and evaluated according to their calculated force–displacement curves, skeleton curves, and ductility coefficients. The results indicate that the CVC structure delivered preferable lateral-bearing capacity and displacement ductility. Finally, according to available design standards, the lateral stiffness of CVC structures could be conventionally controlled and some practical design recommendations are discussed.

scholarly journals Experimental Investigation on Web Crippling Property of High-Strength Cold-Formed (HSCF) Rectangular Steel Tube

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Xianglong Liu ◽  
Jicheng Zhang ◽  
Yuanqi Li ◽  
Lei Zeng ◽  
Guofeng Du
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
High Strength ◽  
Ultimate Bearing Capacity ◽  
Height Ratio ◽  
Steel Tubes ◽  
Web Crippling ◽  
Bearing Plate ◽  
Bearing Load ◽  
Plate Width

To research the web crippling performance (i.e., the ultimate web crippling bearing capacity and ductility) of high-strength cold-formed (HSCF) rectangular steel tubes under concentrated load, thirty-six specimens with different bearing plate width, width-to-height ratio, boundaries, and loading conditions are fabricated and tested in this paper. Particularly, four kinds of boundaries and loading conditions are utilized, including end-two-flange (ETF), end-one-flange (EOF), interior-two-flange (ITF), and interior-one-flange (IOF). Research revealed the failure modes of HSCF rectangular steel tubes under concentrated loads applied at the end or interior. Moreover, the load-displacement curves and load-strain curves are obtained. The results show that the ultimate crippling capacity of webs increases significantly with larger bearing plate width and width-to-height ratio. Specimens subjected to interior bearing load have higher ultimate strength and deformation capacity than counterparts that are subjected to bearing load at the end. Additionally, in the middle of the compression web, all strain measuring points enter the plasticity stage and finally appear in the plastic hinge area. Subsequently, the failure modes and ultimate bearing capacity are simulated by the finite element method (FEM), which is implemented via ABAQUS. By comparing the test results with the numerical values, demonstrate the effectiveness of the proposed numerical simulation on investigating the failure modes and the ultimate bearing capacity of HSCF rectangular steel tubes. Finally, regarding the conservative and dangerous calculation of web crippling ultimate bearing capacity in current codes, we can provide a good guidance for future work, particularly the proposed calculation equations for ultimate bearing capacity of HSCF rectangular steel tubes.

scholarly journals Experimental - theoretical study of axially compressed cold formed steel profiles

2011 ◽  
Vol 9 (3) ◽  
pp. 367-378
Author(s):  
Miroslav Besevic ◽  
Danijel Kukaras
Keyword(s):  
Numerical Analysis ◽  
Bearing Capacity ◽  
Cross Sections ◽  
High Strength ◽  
Static And Dynamic Analysis ◽  
Finite Element Software ◽  
Steel Members ◽  
Cold Formed Steel ◽  
Methods Numerical

Analysis of axially compressed steel members made of cold formed profiles presented in this paper was conducted through both experimental and numerical methods. Numerical analysis was conducted by means of "PAK" finite element software designed for nonlinear static and dynamic analysis of structures. Results of numerical analysis included ultimate bearing capacity with corresponding middle section force-deflection graphs and buckling curves. Extensive experimental investigation were also concentrated on determination of bearing capacity and buckling curves. Experiments were conducted on five series with six specimens each for slenderness values of 50, 70, 90, 110 and 120. Compressed simply supported members were analyzed on Amsler Spherical pin support with unique electronical equipment and software. Besides determination of forcedeflection curves, strains were measured in 18 or 12 cross sections along the height of the members. Analysis included comparisons with results obtained by different authors in this field recently published in international journals. Special attention was dedicated to experiments conducted on high strength and stainless steel members.

Experimental Investigation on Joining Dissimilar Aluminum Alloy 6061 to TRIP 780/800 Steel Through Friction Stir Welding

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Xun Liu ◽  
Shuhuai Lan ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Cross Sections ◽  
Failure Modes ◽  
High Strength ◽  
Tensile Tests ◽  
Weld Strength ◽  
Friction Stir ◽  
Aluminum Alloy 6061 ◽  
Alloy 6061

Friction stir welding (FSW) technique has been successfully applied to butt joining of aluminum alloy 6061-T6 to one type of advanced high strength steel (AHSS), transformation induced plasticity (TRIP) 780/800 with the highest weld strength reaching 85% of the base aluminum alloy. Mechanical welding forces and temperature were measured under various sets of process parameters and their relationships were investigated, which also helped explain the observed macrostructure of the weld cross section. Compared with FSW of similar aluminum alloys, only one peak of axial force occurred during the plunge stage. Three failure modes were identified during tensile tests of weld specimens, which were further analyzed based on the microstructure of joint cross sections. Intermetallic compound (IMC) layer with appropriate thickness and morphology was shown to be beneficial for enhancing the strength of Al–Fe interface.

Study on failure mechanism and end construction influences of double rectangular tube assembled buckling-restrained brace

2016 ◽  
Vol 20 (10) ◽  
pp. 1572-1585 ◽  
Author(s):  
Zi-qin Jiang ◽  
Yan-lin Guo ◽  
Ai-Lin Zhang ◽  
Chao Dou ◽  
Cai-Xia Zhang
Keyword(s):  
Bearing Capacity ◽  
Rational Design ◽  
Failure Modes ◽  
High Strength ◽  
Design Parameters ◽  
Local Pressure ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Buckling Restrained Brace ◽  
Rectangular Tube

The double rectangular tube assembled buckling-restrained brace is a new type of buckling energy consumption buckling-restrained brace. Because of its external restraining members, which are bound by high-strength bolts, its mechanical mechanism is more complicated and its failure modes are more varied. In this study, the double rectangular tube assembled buckling-restrained brace composition and three types of end constructions are introduced in detail. The influences of different design parameters on the performance of double rectangular tube assembled buckling-restrained brace are studied by numerical analysis methods; the possible failure modes and the influence of the end strengthening construction of double rectangular tube assembled buckling-restrained brace are also investigated, and a number of suggestions are proposed to improve this design. This study shows that the pinned double rectangular tube assembled buckling-restrained brace has four types of typical failure modes, namely, overall buckling failure, external end local pressure-bearing failure, bending failure of the extended strengthened core region and bolt threading failure. Rational design can prevent a buckling-restrained brace from losing its load-bearing capacity. In addition, compared with the end strengthening scheme with an external hoop, the end strengthening scheme with a strengthened bench can improve the load-bearing capacity of the double rectangular tube assembled buckling-restrained brace more effectively, and a reasonable design can also save materials.

Study on Acoustic Emission and Failure Modes of Rock in Uniaxial Compression Test

2011 ◽  
Vol 261-263 ◽  
pp. 1393-1400
Author(s):  
Ji Liang Zhang ◽  
Chang Hong Li
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Compression Test ◽  
Failure Modes ◽  
Soft Rock ◽  
Development Stage ◽  
Uniaxial Compression Test ◽  
Whole Process ◽  
Shear Rupture

Based on uniaxial compression test, the mechanical properties and acoustic emission characteristics of rock had been obtained, including the relationship between AE and time, AE and stress level, and so on, in the whole process of rock failure. Research shows AE rate of rock has the subparagraph features obviously. There are three obvious AE sections for the higher strength elastic-brittle rock: First section is compaction stage, corresponding stress is 10% of compressive strength of rock; Second section is crack-development stage, corresponding stress is 80% of compressive strength; Third section is rupture stage, corresponding stress is the compressive strength. Furthermore, AE signals for the rupture stage is strongest. The law is still correct in cycle loading conditions. However, the subparagraph phenomenon isn’t clear for elastic-plastic rock, and the AE peak is lagging behind the ultimate strength of rock, the AE signal in the decline stage of strength is the most intensive and strong. The lagging phenomenon is due to X-shear rupture model of soft rock. The significant stress concentration in cone tip between the two relative extrusion cones leads to local rock broken seriously. Then, many acoustic signals have been observed.

scholarly journals Failure modes in high strength and stiffness to weight scaffolds produced by Selective Laser Melting

2015 ◽  
Vol 67 ◽  
pp. 501-508 ◽  
Author(s):  
Timothy B. Sercombe ◽  
Xiaoxue Xu ◽  
V.J. Challis ◽  
Richard Green ◽  
Sheng Yue ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Failure Modes ◽  
High Strength ◽  
Laser Melting ◽  
Strength And Stiffness

scholarly journals Study on an Innovative Flange Bolted-Welded Connection

2015 ◽  
Vol 9 (1) ◽  
pp. 870-875
Author(s):  
Yufeng Jiao ◽  
Guo Zhao
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Experimental Studies ◽  
High Strength ◽  
Bottom Flange ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Hybrid Joint ◽  
Welded Connection ◽  
Cyclic Loading Tests

This paper proposes a new type of spliced joint, named flange bolted-welded hybrid joint, which is designed to splice I-shape beam to facilitate the construction of industrialized buildings. The flange, welded with the bottom beam flange as well as the web close to bottom flange, are jointed by high strength bolts. Stiffening plate is welded at top of the flange while downhand welding and high strength friction grip bolts are used for the top beam flange and the beam web, respectively. The connection reduces the construction period and costs. In this paper, monotonic and reversed cyclic loading tests were conducted on three full-scale specimens of this innovative joint to investigate its load-bearing capacity, energy-dissipating capacity and failure modes. The results indicate that the joint has high load-bearing capacity and great ductility. The failure mode is due to the slippage of flange bolts as well as the gap development between the two flange plates. The experimental studies enabled improvement of the design of the connection to be used in moment-resisting steel frame structures.

scholarly journals Bending Reinforcement of Full-Scale Timber Beams with Mechanically Attached GFRP Composite Plates

2017 ◽  
Vol 747 ◽  
pp. 212-219 ◽  
Author(s):  
Tomas Pupsys ◽  
Marco Corradi ◽  
Antonio Borri ◽  
Leon Amess
Keyword(s):  
Failure Modes ◽  
Composite Plates ◽  
High Strength ◽  
Outer Diameter ◽  
Head Coach ◽  
Mechanical Reinforcement ◽  
Experimental Campaign ◽  
Gfrp Composite ◽  
Bending Capacity ◽  
Timber Beams

This paper presents the results of an experimental campaign aimed to evaluate the performance of timber beams strengthened in bending using GFRP (Glass Fiber Reinforced Polymer) plates mechanically attached with high-strength metal screws. Modest ratios of GFRP composite reinforcement can increase beam load-carrying capacity and manipulate failure mode from the brittle tensile in the unreinforced beams to a more extensible failure in the strengthened timber beams. Application of mechanical reinforcement presents a solution of reversibility, compatibility and durability for reinforced timber. The experimental campaign focused on load-deflection relationship and failure modes in order to increase the bending capacity and stiffness of the timber beam. Oak beams with dimensions 145 x 145 x 2450 mm were reinforced with un-bonded pultruded GFRP plates. Hexagon head coach screws 16 mm diameter, 130 mm length, grade 8.8, were used to mechanically attach the reinforcement along with 34 mm outer diameter fender washers, distributing the fastening load away from the screw’s position. All beams were tested until failure under the four-point bending configuration. Experimental results demonstrate the effectiveness of the reinforcement method and ability to reversibly repair the timber, representing a capability to be utilised in the new constructions or restoration of timber structures.

The Use of High-Strength Composites in the Reinforcement of Timber

2010 ◽  
Vol 133-134 ◽  
pp. 941-946 ◽  
Author(s):  
Bohumil Kasal ◽  
Andreas Heiduschke
Keyword(s):  
Brittle Failure ◽  
Failure Modes ◽  
State Of The Art ◽  
High Strength ◽  
The State ◽  
Structural Timber ◽  
Timber Structures ◽  
Structural Members ◽  
Entire Surface ◽  
Strength And Stiffness

The use of high-strength composites in the reinforcement of structural timber has been documented to enhance the strength and stiffness of wood structural members. Global reinforcement is applied over the entire surface of the reinforced member. Local reinforcement is a targeted strengthening of highly-stressed zones susceptible to failure. Both types of reinforcement enhance the capacity of the reinforced members and mitigate brittle failure modes. This paper presents an overview of the application of fiber-based composites in the reinforcement of beams, columns and connections of timber structures and discusses the state-of-the-art technologies in reinforcement. The applications are illustrated on the reinforcement of beams, arches, frames and beam-to-column connections.

Sign in / Sign up

Export Citation Format

Share Document