Unequal depth beam to column connection joint

Ben Mou,Aijia Zhang,Wei Pan 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.6

This paper presents the seismic performance of seven beam-column joints with an eccentricity between beam depths under cyclic loadings. The failure modes of the panel zone were divided into two types. One was the shear force failure that appeared in the entire panel zone (SFEPZ), the other was the shear force failure that appeared in the partial panel zone (SFPPZ). Seven finite element models were established using multi-scale methods. Compared with the experimental specimens, the hysteretic loops exhibited a similar trend. The multi-scale models could accurately simulate the experimental results. Furthermore, the calculation formulas of yield and plastic shear capacity of unequal-depth joints with outer annular stiffener were proposed.

Exposed Reinforced Concrete-Filled Steel Tubular (RCFST) column-base joint with high-strength

Ben Mou,Zian Wang,Qiyun Qiao,Wanqiu Zhou 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.1

The weld quality has always been an important factor affecting the development of exposed CFT column-base joint. In this paper, a new type of exposed RCFST column-base joint is proposed, in which the high strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens, the varying axial force ratio (0, 0.25 and 0.5), were tested under cyclic loadings. In addition, the bending moment capacity, energy dissipation capacity and deformation capacity of column-base joints were clarified. The experimental results indicated that the axial force ratio increases the stiffness and the bending moment and improves the energy dissipation capacity of column-base joints. This is because a large axial force can limit the slip between steel tubular and infilled concrete effectively. The specimens show stable hysteresis behavior.

A Prospect of Optical Communications in Taiwan

Ben Mou Yu,Jy Wang Liaw,Wann Yih Guo,Jin San Shei 한국통신학회 1997 OPTOELECTRONICS & COMMUNICATIONS CONFERENCE Vol.2 No.1

Experimental and numerical investigation on exposed RCFST column-base Joint

Ben Mou,Xingchen Yan,Qiyun Qiao,Wanqiu Zhou 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.5

This paper investigates the seismic performance of exposed RCFST column-base joints, in which the high-strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens with different axial force ratios (n = 0, 0.25, and 0.5) were tested under cyclic loadings. Finite element analysis (FEA) models were validated in the basic indexes and failure mode. The hysteresis behavior of the exposed RCFST columnbase joints was studied by the parametrical analysis including six parameters: width of column (D), width-thickness ratio (D/t), axial force ratio (n), shear-span ratio (L/D), steel tube strength (fy) and concrete strength (fc). The bending moment of the exposed RCFST column-base joint increased with D, fy and fc. But the D/t and L/D play a little effect on the bending capacity of the new column-base joint. Finally, the calculation formula is proposed to assess the bending moment capacities, and the accuracy and stability of the formula are verified.

Residual Strength of Steel-Reinforced Concrete-Filled Square Steel Tubular (SRCFST) Stub Columns After Exposure to ISO-834 Standard Fire

Fanqin Meng,Meichun Zhu,Ben Mou,Baojie He 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

Steel-reinforced concrete-fi lled square steel tubular (SRCFST) column has been acknowledged as a progressive form from the steel–concrete composite system, having a higher load-bearing capacity. Aiming at lying the foundations for SRCFST full-scale research after fi re exposure, this paper has studied the axial compression behavior of SRCFST stub columns after diff erent modes of fi re exposure. To start with, temperature distributions, failure patterns and load–strain relationships of four existing SRCFST columns were experimentally analyzed. Based on this, numerical models of square SRCFST columns with suffi cient correctness and eff ectiveness were established for further holistically examining impacts of fi re duration time, yield strength of steel tube, compressive strength of concrete, confi nement index, section steel index and sectional dimensions on residual strength of SRCFST columns. The results indicate that residual strength of square SRCFST columns decrease signifi cantly with fi re duration time, sectional dimensions and section steel index, while yield strength of steel, compressive strength of concrete and confi nement index exert negligible eff ects. Afterwards, predictive formulas that can calculate residual strength index of square SRCFST columns under diff erent patterns of fi re exposure were proposed.

Numerical Modeling on Post-Local Buckling Behavior of Circular and Square Concrete-Filled Steel Tubular Beam Columns

Yongtao Bai,Xuchuan Lin,Ben Mou 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.2

In concrete-filled steel tubular (CFST) beam-columns under cyclic loadings, local buckling of restrained steel tube, crushing and slipping of the confined concrete could have significant influences on strength and stiffness degradation. This paper presents a numerical model based on fiber element discretization for simulating the deterioration behaviour of both rectangular and circular CFST beam columns under axial load and cyclic loading. Uniaxial stress-strain relationships for steel and concrete in CFST beam columns are proposed by introducing unified parameters to control the extent of deterioration. Axial contraction caused by local buckling was accounted by defining an inelastic region that promises plasticity and strength degradation. The numerical model was validated by comparing the simulation results and the associated experimental results. The influences of diameter-to-thickness ratio, concrete and steel strength ranging from normal strength to high strength on the deterioration behavior of circular and rectangular CFST beam-columns were analyzed. Finally, through recognizing the limit state to trigger global strength degradation of a CFST frame, the developed numerical model is applicable for simulating global behavior of CFST frames under collapse-level deformations.

Effect of spiral spacing on axial compressive behavior of square reinforced concrete filled steel tube (RCFST) columns

Qiyun Qiao,Wenwen Zhang,Ben Mou,Wanlin Cao 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.6

Spiral spacing effect on axial compressive behavior of reinforced concrete filled steel tube (RCFST) stub column is experimentally investigated in this paper. A total of twenty specimens including sixteen square RCFST columns and four benchmarked conventional square concrete filled steel tube (CFST) columns are fabricated and tested. Test variables include spiral spacing (spiral ratio) and concrete strength. The failure modes, load versus displacement curves, compressive rigidity, axial compressive strength, and ductility of the specimens are obtained and analyzed. Especially, the effect of spiral spacing on axial compressive strength and ductility is investigated and discussed in detail. Test results show that heavily arranged spirals considerably increase the ultimate compressive strength but lightly arranged spirals have no obvious effect on the ultimate strength. In practical design, the effect of spirals on RCFST column strength should be considered only when spirals are heavily arranged. Spiral spacing has a considerable effect on increasing the post-peak ductility of RCFST columns. Decreasing of the spiral spacing considerably increases the post-peak ductility of the RCFSTs. When the concrete strength increases, ultimate strength increases but the ductility decreases, due to the brittleness of the higher strength concrete. Arranging spirals, even with a rather small amount of spirals, is an economical and easy solution for improving the ductility of RCFST columns with highstrength concrete. Ultimate compressive strengths of the columns are calculated according to the codes EC4 (2004), GB 50936 (2014), AIJ (2008), and ACI 318 (2014). The ultimate strength of RCFST stub columns can be most precisely evaluated using standard GB 50936 (2014) considering the effect of spiral confinement on core concrete.

Non-linear FEA of mechanical properties of modular prefabricated steel-concrete composite joints

Wu Cheng Long,Kan Jian Cheng,Liu Ji Ming,Mou Ben 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.4

This paper study the seismic performance of modular prefabricated SRC column to steel beam composite joint (MPCJ) under static loading. Numerical modeling of MPCJs with three different beam-end connections was carried out in ABAQUS. Results of the numerical calculation were compared with existing quasi-static test results to verify the feasibility of the numerical model. The model was then used to analyze changes in the moment-rotation relation, failure mode, ductility, stiffness, and bolt stress in the joint between the column and joint module. Besides, stress distributions in the joints were analyzed along different stress paths. Under monotonic loading, the mechanical performance of the MPCJ is significantly affected by the beam end connection mode. Failure of the MPCJ mainly occurs at the beam end connection, thus, the aim of keeping the plastic hinge away from the joint core and preventing shear failure is achieved. Furthermore, the maximum story drift ratio is 3.9–5 times greater than the recommended limit, which indicates good ductility and deformation performance. The MPCJ of the three-beam end connection methods is all semi-rigid connections. The beam end structure will have a large influence on the bolt tension and stress distribution. According to the test research results, a nonlinear model with three parameters including joint cover plate cantilever section length, flange connecting plate thickness and flange connecting plate weld length was established. The theoretical calculation results was consistent with the results of the numerical simulation. MPCJs can be designed based on the proposed theoretical calculation formula.