scholarly journals Static Behavior of a Modified Through-Core Connection between CFST Column and Composite Beam

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Qi-shi Zhou ◽  
Hua-wei Fu ◽  
Xu-hong Zhou ◽  
Yu-jie Yu ◽  
Qian-ren Wang
Keyword(s):  
Load Transfer ◽  
Steel Beams ◽  
Load Bearing ◽  
Rigid Connection ◽  
Rc Slab ◽  
Internal Forces ◽  
Loading Tests ◽  
Cfst Columns ◽  
Concrete Filling ◽  
Connection Design

Through-core connection has been proven to be an ideal solution to ensure a rigid connection between steel beams and CFST columns. However, the traditional through-core connection sometimes encounters concrete filling problems. A modified through-core connection design with details of reduced flange width was therefore proposed. Through-core reinforcements were added as supplements for tension load transfer. The monotonic loading tests and comprehensive FE simulations were performed to investigate the load bearing performance and working mechanism of this modified connection. The results indicated that the modified through-core connection presented plasticity hinge failure at the beam end and crack formulation and progradation at the RC slab. The reduced flange width reduced the strength of the connection, but the reduction extent was limited. Due to the through-core construction, the majority of internal forces at the beam were directly transferred into the column. The through-core reinforcement can effectively participate in load bearing after the connection yields. The flange width reduction extent and the length of the reduction region must be controlled to ensure sufficient connection strength. The number of shear studs and TC reinforcements can influence the load bearing ability, and design suggestions are provided for the modified through-core connection.

Seismic Behavior of Top-weld Bottom-bolt Joints between CFST Columns and H-beams

2021 ◽  
Author(s):  
Jianxin Zhang ◽  
Xian Rong ◽  
Xiaowei Zhang ◽  
Yanyan Li ◽  
Yansheng Du ◽  
...  
Keyword(s):  
Failure Mode ◽  
Design Criterion ◽  
Steel Beams ◽  
Tubular Columns ◽  
Weak Beam ◽  
Beam Design ◽  
Loading Tests ◽  
Reversed Loading ◽  
Cfst Columns ◽  
Beam Height

Abstract In recent decades, connections between concrete-filled steel tubular columns (CFST) and H-steel beams have been well designed and implemented. However, owing to poor construction quality, brittle failure often occurs at weld seams. In this study, an innovative joint was developed to connect CFST columns and H-steel beams using a top-weld bottom-bolt (TWBB) connection to minimize the effect of welding quality on the seismic resistance of joints. Six specimens were designed for cycle-reversed loading tests to discuss the seismic performance of this joint. Four configurations, including different connection methods, beam heights, column forms, and stiffener thicknesses, were considered in the test. The impacts of different configuration forms on the failure mode, strength, stiffness, ductility, and energy dissipation of the specimens were evaluated. The test results demonstrated that the columns with or without concrete had a significant effect on the deformation capacity. However, a smaller effect was observed on other indicators. The replacement of the through-diaphragm and an increase in the beam height adversely influenced the ductility of the joint. Moreover, changing the stiffener thickness and using a full-bolted connection affected the failure mode. The joint type analyzed in this study satisfies the strong column–weak beam design criterion and the related seismic provisions.

scholarly journals Axial Behaviour of Slender RC Circular Columns Strengthened with Circular CFST Jackets

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yiyan Lu ◽  
Tao Zhu ◽  
Shan Li ◽  
Weijie Li ◽  
Na Li
Keyword(s):  
Bearing Capacity ◽  
Ductile Failure ◽  
Steel Tube ◽  
Experimental Results ◽  
Strengthening Effect ◽  
Load Bearing Capacity ◽  
Rc Columns ◽  
Load Bearing ◽  
Cfst Columns ◽  
Material Utilization

This paper investigates the axial behavior of slender reinforced concrete (RC) columns strengthened with concrete filled steel tube (CFST) jacketing technique. It is realized by pouring self-compacting concrete (SCC) into the gap between inner original slender RC columns and outer steel tubes. Nine specimens were prepared and tested to failure under axial compression: a control specimen without strengthening and eight specimens with heights ranging between 1240 and 2140 mm strengthened with CFST jacketing. Experimental variables included four different length-to-diameter (L/D) ratios, three different diameter-to-thickness (D/t) ratios, and three different SCC strengths. The experimental results showed that the outer steel tube provided confinement to the SCC and original slender RC columns and thus effectively improved the behavior of slender RC columns. The failure mode of slender RC columns was changed from brittle failure (concrete peel-off) into ductile failure (global bending) after strengthening. And, the load-bearing capacity, material utilization, and ductility of slender RC columns were significantly enhanced. The strengthening effect of CFST jacketing decreased with the increase of L/D ratio and D/t ratio but showed little variation with higher SCC strength. An existing expression of load-bearing capacity for traditional CFST columns was extended to propose a formula for the load-bearing capacity of CFST jacketed columns, and the predictions showed good agreement with the experimental results.

scholarly journals Load-Bearing Capacity of Zirconia Crowns Screwed to Multi-Unit Abutments with and without a Titanium Base: An In Vitro Pilot Study

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3056
Author(s):  
Hadas Heller ◽  
Adi Arieli ◽  
Ilan Beitlitum ◽  
Raphael Pilo ◽  
Shifra Levartovsky
Keyword(s):  
Failure Modes ◽  
Load Bearing ◽  
Zirconia Crowns ◽  
Group A ◽  
Monolithic Zirconia ◽  
Loading Tests ◽  
Group B ◽  
Iso 14801 ◽  
Static And Dynamic Loading

The static and dynamic load-bearing capacities and failure modes of zirconia crowns screwed to multi-unit abutments (MUAs) with and without a titanium base (T-base) were determined. Thirty-six monolithic zirconia crowns screwed to straight MUAs torqued to laboratory analogs (30 Ncm) were assigned to two groups (n = 18). In group A, the zirconia crowns were screwed directly to the MUAs; in group B, the zirconia crowns were cemented to the T-base and screwed to the MUAs. All specimens were aged in 100% humidity (37 °C) for one month and subjected to thermocycling (20,000 cycles). Afterwards, the specimens underwent static and dynamic loading tests following ISO 14801. The failure modes were evaluated by stereomicroscopy (20×). There was an unequivocally similar trend in the S-N plots of both specimen groups. The load at which the specimens survived 5,000,000 cycles was 250 N for both groups. Group A failed mainly within the metal, and zirconia failure occurred only at a high loading force. Group B exhibited failure within the metal mostly in conjunction with adhesive failure between the zirconia and T-base. Zirconia restoration screwed directly to an MUA is a viable option, but further studies with larger sample sizes are warranted.

scholarly journals Seismic Damage Investigation of Spatial Frames with Steel Beams Connected to L-Shaped Concrete-Filled Steel Tubular (CFST) Columns

2018 ◽  
Vol 8 (10) ◽  
pp. 1713 ◽  
Author(s):  
Jicheng Zhang ◽  
Yong Li ◽  
Yu Zheng ◽  
Zhijie Wang
Keyword(s):  
Finite Element ◽  
Frame Structures ◽  
Steel Beams ◽  
Element Analysis ◽  
Testing Specimen ◽  
Tubular Columns ◽  
Finite Element Software ◽  
Fea Model ◽  
Composite Frames ◽  
Cfst Columns

Currently, the frame structures with special-shaped concrete-filled steel tubular columns have been widely used in super high-rise buildings. Those structural members can be used to improve architectural space. To investigate the seismic behavior of spatial composite frames that were constructed by connecting steel beams to L-shaped concrete-filled steel tubular (CFST) columns, a finite element analysis (FEA) model using commercial finite element software ABAQUS was proposed to simulate the behavior of the composite spatial frames under a static axial load on columns and a fully-reversed lateral cyclic load applied to frames in this paper. Several nonlinear factors, including geometry and material properties, were taken into account in this FEA model. Four spatial specimens were designed, and the corresponding experiments were conducted to verify the proposed FEA model. Each testing specimen was two-story structure consisting of eight single span steel beams and four L-shaped CFST columns. The test results showed that the proposed FEA model in this paper could evaluate the behavior of the composite spatial frames accurately. Based on the results of the nonlinear analysis, the stress developing progress of columns is investigated. The load transferring mechanism and failure mechanism are also determined. The results are discussed and conclusions about the behavior of those spatial frame structures are presented.

Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles

2016 ◽  
Vol 53 (4) ◽  
pp. 696-707 ◽  
Author(s):  
Hai-lei Kou ◽  
Jian Chu ◽  
Wei Guo ◽  
Ming-yi Zhang
Keyword(s):  
Static Loading ◽  
High Strength Concrete ◽  
Large Scale ◽  
Load Transfer ◽  
High Strength ◽  
Neutral Plane ◽  
Shaft Resistance ◽  
Strength Concrete ◽  
Loading Tests ◽  
Residual Force

A large-scale field testing program for the study of residual forces in pre-stressed high-strength concrete (PHC) pipe piles is presented in this paper. Five open-ended PHC pipe piles with 13 or 18 m in embedded length were installed and used for static loading tests at a building site in Hangzhou, China. All the piles were instrumented with fiber Bragg grating (FBG) strain gauges. The residual forces in these piles were recorded during and after installation. The measured load transfer data along a pile during the static loading tests are reported. The effect of the residual force on the interpretation of the load transfer behavior is discussed. The field data show that residual force along the installed pile increases approximately exponentially to the neutral plane and then reduces towards the toe. The residual force decreases with time to a stable value after pile jacking due to the secondary interaction between the pile and the disturbed soil around the pile and other factors. The large residual forces along the PHC pipe piles significantly affect the evaluation of the pile load distributions, and thus the shaft and toe resistances. The conventional bearing capacity theory tends to overestimate the shaft resistance at positions above the neutral plane and underestimate the shaft resistance at positions below the neutral plane, and the toe resistance for an open-ended PHC pipe piles founded in stratified soils.

scholarly journals Real Cyclic Load-Bearing Test of a Ceramic-Reinforced Slab

2020 ◽  
Vol 10 (5) ◽  
pp. 1763
Author(s):  
Albert Albareda-Valls ◽  
Alicia Rivera-Rogel ◽  
Ignacio Costales-Calvo ◽  
David García-Carrera
Keyword(s):  
Cyclic Load ◽  
Structural Response ◽  
Steel Structure ◽  
Steel Beams ◽  
Load Bearing ◽  
Rc Frames ◽  
Industrial Buildings ◽  
Loading And Unloading ◽  
Low Levels ◽  
The City

Ceramic-reinforced slabs were widely used in Spain during the second half of the 20th century, especially for industrial buildings. This solution was popular due to the lack of materials at that time, as it requires almost no concrete and low ratios of reinforcement. In this study, we present and discuss the results of a real load-bearing test of a real ceramic-reinforced slab, which was loaded and reloaded cyclically for a duration of one week in order to describe any damage under a high-demand loading series. Due to the design of these slabs, the structural response is based more on shear than on bending due to the low levels of concrete and the geometry and location of re-bars. The low ratio of concrete makes these slabs ideal for short-span structures, mainly combined with steel or RC frames. The slab which was analyzed in this study covers a span of 4.88 m between two steel I-beams (IPN400), and corresponds to a building from the mid-1960s in the city of Igualada (Barcelona, Spain). A load-bearing test was carried out up to 7.50 kN/m2 by using two-story sacks full of sand. The supporting steel beams were propped up in order to avoid any interference in the results of the test; without the shoring of the steel structure, deflections would come from the combination of the ceramic slab together with the steel profiles. A process of loading and unloading was repeated for a duration of six days in order to describe the cyclic response of the slab under high levels of loading. Finally, vibration analysis of the slab was also done; the higher the load applied, the higher the fundamental frequency of the cross section, which is more comfortable in terms of serviceability.

scholarly journals CRITICAL TEMPERATURE OF STEEL BEAMS ON THE BASIS OF A LOAD-BEARING FIRE TEST OF 2-STOREY RIGID STEEL FRAME

2014 ◽  
Vol 79 (704) ◽  
pp. 1559-1568
Author(s):  
Takeo HIRASHIMA ◽  
Kazuma OKUWAKI ◽  
Xuansu ZHAO ◽  
Yuki SAGAMI ◽  
Koji TOYODA
Keyword(s):  
Critical Temperature ◽  
Fire Test ◽  
Steel Frame ◽  
Steel Beams ◽  
Load Bearing

The Problem of Consideration Torsion Emergence in Beams

2018 ◽  
Vol 7 (3.2) ◽  
pp. 141 ◽  
Author(s):  
Sergiy Hudz ◽  
Grygorii Gasii ◽  
Volodymyr Pents
Keyword(s):  
Theoretical Model ◽  
Bearing Capacity ◽  
Work Conditions ◽  
Steel Beams ◽  
New Approach ◽  
Initial Imperfections ◽  
Advantages And Disadvantages ◽  
Internal Forces ◽  
Partially Restrained ◽  
Material Saving

The calculation of the steel unrestrained and partially restrained roof beams with initial imperfections main stages is discussed. Restraining can be done by structures attached to the steel beams, namely, profiled flooring and discrete joints. On the basis of the new approach to the internal forces analysis and the geometric properties specification, the purpose was to find and describe the differences in the beam work as the part of roofing, which distinguishes it from the work conditions of the free supported beam. The features of the beam operation with the joint flexural and torsion are singled out. The need to improve the existing theoretical model for present deficiencies elimination is indicated. The bearing capacity determining methods for the flexible elements stability exposed to bending and bending with torsion are compared. Their advantages and disadvantages are revealed. It is proposed to increase the material saving by applying calculations. At the end of the article, conclusions regarding the consideration of investigated factors are given.  

Mechanical Performance of Large Cantilevered CFT Beam-Column Joint in Jiangyin Magic Cube Time Square

2010 ◽  
Vol 163-167 ◽  
pp. 25-31
Author(s):  
Fei Wang ◽  
Yong Feng Luo ◽  
Xiao Nong Guo ◽  
Han Xu ◽  
Ping He
Keyword(s):  
Load Transfer ◽  
Mechanical Performance ◽  
Large Diameter ◽  
Element Model ◽  
Steel Beams ◽  
Test Results ◽  
Column Joint ◽  
Scale Test ◽  
Magic Cube ◽  
The Finite Element Model

The leading building in Magic Cube Time Square in Jiangyin is a rare large-cantilevered structure in China, with the standard floors overhanging 9m outwards. Concrete filled tube columns in large diameter and steel beams are applied in the peripheral part of the building frame. In this research, the full-scale test is conducted to investigate the mechanical performance of the concrete-filled beam-column joint. Self-balanced loading frame with dimensions of 15m×10m×10m is built due to the complexity of the joint, the greatness of load and the difficulty of loading condition. Meanwhile, the finite element model is generated to inspect the performance of the beam-column joint under the test loads for verification. Through comparisons of test results and FEM results, good mechanical performance and reasonable load transfer mechanism of the joint are presented in the paper. It is verified that the joint is reliable under 1.3 times of the design load. The effect of ring stiffeners is also studied in this paper.

Preliminary Study on Dynamic Progressive Collapse Analysis of Spatial Composite Frames with Concrete-Filled Steel Tubular Columns

2012 ◽  
Vol 166-169 ◽  
pp. 164-167 ◽  
Author(s):  
Xiao Yan Zhou ◽  
Jing Xuan Wang ◽  
Wen Da Wang
Keyword(s):  
Progressive Collapse ◽  
Nonlinear Dynamic Analysis ◽  
Internal Force ◽  
Nonlinear Material ◽  
Steel Beams ◽  
Element Analysis ◽  
Composite Frame ◽  
Collapse Analysis ◽  
Cfst Columns ◽  
Progressive Collapse Analysis

This paper presented a progressive collapse analysis of spatial composite frame with concrete-filled steel tubular (CFST) columns. A typical finite element analysis (FEA) model of a 12-story building was established by using ABAQUS. The shell elements were used to simulate the slab, and all of the steel beams and CFST columns were simulated by the beam elements incorporating nonlinear material and geometric, respectively. Nonlinear dynamic analysis was carried out for the sudden loss of columns for different scenarios of column removal, and the capacity of progressive collapse resistance of the 3-D composite frame and other components internal force around the removed column were investigated.

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