scholarly journals Static Strength of Friction-Type High-Strength Bolted T-Stub Connections under Shear and Compression

2020 ◽  
Vol 10 (10) ◽  
pp. 3600 ◽  
Author(s):  
Gangnian Xu ◽  
Youzhi Wang ◽  
Yefeng Du ◽  
Wenshuai Zhao ◽  
Laiyong Wang
Keyword(s):  
Friction Coefficient ◽  
Ultimate Strength ◽  
Compression Ratio ◽  
Failure Modes ◽  
Load Condition ◽  
High Strength ◽  
Shear Capacity ◽  
Displacement Curve ◽  
Clamping Force ◽  
Bolt Diameter

The friction-type high-strength bolted (FHSB) T-stub connection has been widely used in steel structures, due to their good fatigue resistance and ease of installation. While the current studies on FHSB T-stub connections mainly focus on the structural behaviors under both shear and tensile force, no research has been reported on the mechanical responses of the connections under the combined effects of shear and compression. To make up for this gap, this paper presents a novel FHSB T-stub connection, which is simple in structure, definite in load condition, and easy to construct. Static load tests were carried out on 21 specimens under different shear–compression ratios, and the finite-element (FE) models were created for each specimen. The failure modes, initial friction loads and ultimate strengths of the specimens were compared in details. Then, 144 FE models were adopted to analyze the effects of the friction coefficient, shear–compression ratio, bolt diameter and clamping force on the initial friction load and ultimate strength. The results showed that the FHSB T-stub connection under shear and compression mainly suffers from bolt shearing failure. The load–displacement curve generally covers the elastic, yield, hardening and failure stage. If the shear–compression ratio is small and the friction coefficient is large, its curve only contains the elastic and failure stage. The friction coefficient and shear–compression ratio have great impacts on the initial friction load and ultimate strength. For every 1 mm increase in bolt diameter, the initial friction load increased by about 10%, while the ultimate strength increased by about 8.5%. For each 10% increase/decrease of the design clamping force, the initial friction load decreases/increases by 7.8%, while the ultimate load remains basically the same. The proposed formula of shear capacity and self-lock angles of FHSB T-stub connection can be applied to the design of CSS-enhanced prestressed concrete continuous box girder bridges (PSC-CBGBs) and diagonal bracing.

Analysis of seismic performance and research of load capacity of steel reinforced high strength concrete columns with rectangular helical hoops

2020 ◽  
pp. 136943322098165
Author(s):  
Jianyang Xue ◽  
Xin Zhang ◽  
Xiaojun Ke
Keyword(s):  
Failure Mode ◽  
Seismic Performance ◽  
Calculation Method ◽  
High Strength Concrete ◽  
Failure Modes ◽  
Shear Failure ◽  
High Strength ◽  
Shear Capacity ◽  
Strength Concrete ◽  
Shear Span

This paper mainly focused on the seismic performance and shear calculation method of steel reinforced high-strength concrete (SRHC) columns with rectangular helical hoops. An experimental investigation was performed in this paper. Eleven SRHC columns with rectangular helical hoops and one with ordinary hoops were constructed at the laboratory of Guangxi university. The failure modes, hysteresis loops, envelope curves, characteristic loads and displacements and cumulative damage analysis are presented and investigated. It can be seen from the test results that the failure modes of SRHC columns can be divided into three types with the shear span ratio increased, namely, shear baroclinic failure mode, flexure-shear failure mode and flexure failure mode. In addition, the specimens with rectangular helical hoops have plumper hysteretic loops. Shear span ratio is the main influencing factor of characteristic load; the axial compression ratio and concrete strength have less influence on characteristic load, while stirrup ratio has little effect on the characteristic load. Finally, a calculation method for shear capacity of SRHC columns under shear baroclinic failure and flexure-shear failure mode is proposed.

Behaviour of concrete-filled steel tubular members under pure bending and acid rain attack: Test simulation

2018 ◽  
Vol 22 (1) ◽  
pp. 240-253 ◽  
Author(s):  
Li Xie ◽  
Mengcheng Chen ◽  
Wei Sun ◽  
Fang Yuan ◽  
Hong Huang
Keyword(s):  
Acid Rain ◽  
Ultimate Strength ◽  
Failure Modes ◽  
High Strength ◽  
Recycled Concrete ◽  
Steel Plates ◽  
Concrete Aggregate ◽  
Deformation Curves ◽  
Section Modulus ◽  
Four Point Bending

As infrastructure in China continues to develop rapidly, concrete-filled steel tubular structures are increasingly attracting interest for use in construction engineering owing to their high section modulus, high strength and good seismic performance characteristics. However, acid rain occurs throughout much of China, and the mechanical behaviour of concrete-filled steel tubular members may be affected by the corrosive environment created by acid rain. In this study, a total of 14 circular and square-shaped concrete-filled steel tubular members made of different types of concrete (general and recycled) and with varying corrosion rates (0%, 10%, 20% and 30%) were tested under four-point bending. After testing, the flexural behaviour of the corroded and uncorroded concrete-filled steel tubular beams were analysed in detail in terms of their failure modes, moment versus deformation curves and ultimate strength. The results indicate that the corrosion leads to an evident decrease in yield strength, elastic modulus and tensile strain capacity of steel plates and also to a noticeable deterioration in the ultimate strength of the concrete-filled steel tubular members. The replacement of general concrete aggregate with recycled concrete aggregate has little impact on the flexural performance of corroded and uncorroded concrete-filled steel tubular beams. Finally, comparisons were made between the experimental results and predicted ultimate strengths from four existing codes (GB 50936-2014, DB36/J001-2007, AIJ and EN 1994-1-1:2004).

Size effect on the shear capacity of headed studs

2020 ◽  
pp. 136943322096903
Author(s):  
Ahmet Abdullah Dönmez
Keyword(s):  
Size Effect ◽  
Failure Modes ◽  
Three Dimensional ◽  
High Strength ◽  
Shear Capacity ◽  
Microplane Model ◽  
Effect Factor ◽  
Shear Connectors ◽  
Concrete Damage ◽  
Damage Constitutive Model

This study aimed to reveal the existence of size effect on the shear connectors used in the steel-concrete composite beams and slabs. The experimental study contains the monotonic tests of nine pushout specimens with the headed studs. Three-dimensional scaling was used for geometrically similar specimens of three sizes. High strength concrete slabs were used on both sides of the steel I-beam. The failure modes of the specimens include both concrete crushing and stud yielding. Finite element (FE) verification of the specimens was conducted using a realistic concrete damage constitutive model, Microplane Model M7. It is shown that there may be a non-negligible size effect based on the fracture patterns of the composite member. Bažant’s size effect law (SEL) can fit the size effect behavior of the shear connectors. The design equations which do not include a size effect term have high correction factors that overestimate the tested specimens. A new design equation can be drawn using the size effect factor for strength reduction of shear connectors.

scholarly journals Hysteretic performance research on high strength circular concrete-filled thin-walled steel tubular columns

2018 ◽  
Author(s):  
Jiantao Wang ◽  
Qing Sun
Keyword(s):  
Axial Compression ◽  
Compression Ratio ◽  
Failure Modes ◽  
High Strength ◽  
Dissipated Energy ◽  
Ultimate Limit State ◽  
Tubular Columns ◽  
Axial Compression Ratio ◽  
Hysteretic Performance ◽  
Thin Walled

Under violent earthquake motions, the severe damage in critical regions of structures could be ascribed to cumulative damage caused by cyclic loading. Using the high strength (HS) materials in concrete-filled steel tubular (CFST) columns is the effective way and popular tendency to promote the seismic behavior in anti-seismic design. In this paper, an experimental study on the hysteretic performance of high strength circular concrete-filled thin-walled steel tubular columns (HCFTST) columns was carried out. A total of six specimens were tested under constant axial compression combining cyclic lateral loading. The tested parameters were the different combinations of diameter-to-thickness (D/t) ratio, axial compression ratio (n) and concrete cylinder compressive strength (fc).The failure modes, load-displacement hysteretic curves, skeleton curves, dissipated energy and stiffness degradation were examined in detail. Through the experiment analysis result, it indicates that the ultimate limit state is reached as the severe local buckling and rupture of the steel tubes accompanying the core concrete crushing occur. Using high strength materials could have a larger elastic deformation capacity and the higher axial compression ratio within test scopes could motivate the potential of HS materials. In brief, the HCFTST columns with ultra-large D/t ratios under reasonable design could perform excellent hysteretic performance, which can be applied in earthquake-prone regions widely.

Seismic Performance and Confinement Reinforcement Design of High-Strength Concrete Columns Confined with High-Strength Stirrups

2021 ◽  
pp. 136943322199249
Author(s):  
Kun Yang ◽  
Qing-xuan Shi ◽  
Qi Lin
Keyword(s):  
Hysteresis Loop ◽  
Axial Compression ◽  
Compression Ratio ◽  
High Strength Concrete ◽  
Failure Modes ◽  
Failure Process ◽  
High Strength ◽  
Effective Measure ◽  
Strength Concrete ◽  
Axial Compression Ratio

This paper aims at analyzing the failure process, failure modes, characteristics of hysteresis loop and the ductility of 10 high-strength concrete (HSC) columns confined by high-strength complex stirrups under cyclic lateral force and a higher constant axial loading. It is indicated that the hysteresis loop of this type of columns still show plump spindle-shaped at higher axial compression ratio, which shows better ductility, energy dissipation and anti-collapse performance. Therefore, it is an effective measure of setting high-strength stirrups to ensure the good ductility of HSC columns under high axial compression ratio and to increase the limit value of axial compression ratio. The stress of transverse reinforcement is evaluated, which shows that high-strength stirrups have yielded when most of the specimens are destroyed, and the strength of stirrups can be fully developed to provide a better effect of restraint. Based on a large number of experimental data, the relationships between the limit drift, the ductility coefficient of HSC columns and axial compression ratio, stirrup characteristic values, covering layer as well as longitudinal reinforcement ratio are established; the calculation formula of minimum stirrups characteristic value of HSC columns at different seismic levels considering of axial compression ratio is presented.

scholarly journals Compressive behaviours of octet-truss lattices

2020 ◽  
Vol 234 (16) ◽  
pp. 3257-3269 ◽  
Author(s):  
Yifan Li ◽  
Huaiyuan Gu ◽  
Martyn Pavier ◽  
Harry Coules
Keyword(s):  
Failure Modes ◽  
Density Ratio ◽  
Three Dimensional ◽  
Compressive Load ◽  
High Strength ◽  
Detailed Comparison ◽  
Compressive Response ◽  
Beam Elements ◽  
Structural Applications ◽  
Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

scholarly journals Design Optimization of Explosion-Resistant System Consisting of Steel Slab and CFRP Frame

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2589
Author(s):  
Jung J. Kim
Keyword(s):  
Hybrid System ◽  
Impact Load ◽  
Load Condition ◽  
High Strength ◽  
Dynamic Responses ◽  
Elastoplastic Behavior ◽  
Reinforced Polymer ◽  
Steel Slab ◽  
Strength Material

This study presents an explosion-resistant hybrid system containing a steel slab and a carbon fiber-reinforced polymer (CFRP) frame. CFRP, which is a high-strength material, acts as an impact reflection part. Steel slab, which is a high-ductility material, plays a role as an impact energy absorption part. Based on the elastoplastic behavior of steel, a numerical model is proposed to simulate the dynamic responses of the hybrid system under the air pressure from an explosion. Based on this, a case study is conducted to analyze and identify the optimal design of the proposed hybrid system, which is subjected to an impact load condition. The observations from the case study show the optimal thicknesses of 8.2 and 7 mm for a steel slab and a ϕ100 mm CFRP pipe for the hybrid system, respectively. In addition, the ability of the proposed hybrid system to resist an uncertain explosion is demonstrated in the case study based on the reliability methodology.

scholarly journals Microstructure and Mechanical Performance of Resistance Spot Welded Martensitic Advanced High Strength Steel

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1021
Author(s):  
Yunzhao Li ◽  
Huaping Tang ◽  
Ruilin Lai
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Strong Dependence ◽  
High Strength ◽  
Weld Nugget ◽  
Resistance Spot ◽  
Pull Out ◽  
Cross Tension ◽  
Spot Welded

Resistance spot welded 1.2 mm (t)-thick 1400 MPa martensitic steel (MS1400) samples are fabricated and their microstructure, mechanical properties are investigated thoroughly. The mechanical performance and failure modes exhibit a strong dependence on weld-nugget size. The pull-out failure mode for MS1400 steel resistance spot welds does not follow the conventional weld-nugget size recommendation criteria of 4t0.5. Significant softening was observed due to dual phase microstructure of ferrite and martensite in the inter-critical heat affected zone (HAZ) and tempered martensite (TM) structure in sub-critical HAZ. However, the upper-critical HAZ exhibits obvious higher hardness than the nugget zone (NZ). In addition, the mechanical properties show that the cross-tension strength (CTS) is about one quarter of the tension-shear strength (TSS) of MS1400 weld joints, whilst the absorbed energy of cross-tension and tension-shear are almost identical.

Accelerated testing of super lightweight UHPC waffle deck under heavy vehicle simulator

2021 ◽  
Vol 16 (2-3) ◽  
pp. 61-74
Author(s):  
Sahar Ghasemi ◽  
Amir Mirmiran ◽  
Yulin Xiao ◽  
Kevin Mackie
Keyword(s):  
High Performance ◽  
Failure Modes ◽  
High Performance Concrete ◽  
High Strength ◽  
Heavy Vehicle ◽  
Wheel Load ◽  
Element Analysis ◽  
Vehicle Simulator ◽  
Pavement Testing ◽  
Heavy Vehicle Simulator

A super lightweight deck can enhance load rating and functionality of a bridge, especially those identified as structurally deficient. This study was aimed to develop and experimentally validate a novel bridge deck as an ultra-lightweight low-profile waffle slab of ultra-high-performance concrete (UHPC) with either carbon fiber reinforced polymer (CFRP) or high strength steel (HSS) reinforcement. The proposed system lends itself to accelerated bridge construction, rapid deck replacement in bridges with load restrictions, and bridge widening applications without the need to replace girders. Performance and failure modes of the proposed deck were initially assessed through extensive lab experiments and finite element analysis, which together confirmed that the proposed deck panel meets the AASHTO LRFD requirements. The proposed deck system is not susceptible to punching shear of its thin slab and fails in a rather ductile manner. To evaluate its long-term performance, the system was further tested under the dynamic impact of wheel load at the Accelerated Pavement Testing (APT) facility of the Florida Department of Transportation using a Heavy Vehicle Simulator (HVS).

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