Abstract
Fiber-composites constructed of reinforced polymer have recently acquired popularity as an alternative to other
traditional materials used in construction reinforcement. These composites are remarkable because of their low weight, high tensile strength compared to its weight ratio, corrosion resistance, and ease of installation in strengthening and retrofitting structural parts. In this work, using the ABAQUS analytical program's finite element algorithm to analyze 279 models, the effects of multiple parameters on the behavior of RC beams externally bonded and retrofitted with one of three types of polymeric fibers were investigated. This was achieved by modeling a quarter of the complete beams using the beams' symmetry, where the cohesive bond model of the FRP-concrete interface and the isotropic elastic characteristics of FRP were applied. Good agreement was found between experimental data and numerical results when the material models were adopted with experimental work. Investigations indicate that a typical collapse happens when the cohesive bond breaks, and that while
increasing the shear or concrete strength improves the allowable loading capacity, but it does not completely prevent the debonding failure of the beam. U-wrap anchor applications at the end of external bonding are a partial solution to the problem of early collapse in the more rigid fibers, like carbon fiber polymers. The effect of using U-wrap anchors to reduce early collapse varies depending on the stiffness of the fiber; it is effective in the least rigid fibers, like glass fiber-reinforced polymers, but less
effective by increasing the stiffness of the fibers, like aramid fiber-reinforced polymers. Furthermore, increasing the U-wrap anchor width is more effective in eliminating the debonding than increasing its height.
Key Words
debonding failure; externally bonded (EB); fiber reinforced polymer (FRP); finite element method (FEM); retrofitted reinforced concrete (RRC)
Address
Yusuf Sümer, M. Nawar Zakour: Department of Civil Engineering, Sakarya University of Applied Sciences, Sakarya, Turkey
Muhammed Öztemel: Graduate Education Institute, Sakarya University of Applied Sciences, Sakarya, Turkey
Abstract
T-shaped reinforced concrete (RC) walls are widely used in high-rise structures due to their high strength and stiffness in both principal directions. However, the enhancement of flexural resistance pro-vided by the flange in T-shaped RC walls increases their vulnerability to shear failure. Additionally, the flange under tension and compression states exerts different influences on the shear mechanism and shear capacity of T-shaped walls, increasing the difficulty of predicting shear capacity. Addressing these is-sues, this study conducted quasi-static tests on T-shaped RC squat walls and utilized finite element simulations to investigate the influence of parameters on shear capacity, and a calculation method for shear capacity is established using the strut-and-tie model. The results indicate that a higher shear capacity is achieved when the flange is in tension, accompanied by steeper diagonal cracks. The proposed method considers the influence of flanges under different loading states by adjusting the contribution of the con-crete diagonal compressive strut, and the maximum margin of error between experimental results is less than 15%.
Address
Bin Wang, Zhou Yang, Qing-Xuan Shi, Han Li: School of Civil Engineering, Xi'an University of Architecture & Technology, No. 13, Middle Yanta Road, Xi'an, 710055, China; Key Lab of Structure Engineering and Earthquake Resistance, Ministry of Education (XAUAT), No. 13, Middle Yanta Road, Xi'an, 710055, China
Wen-Zhe Cai: School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, No. 19, South Jinhua Road, Xi'an, 710048, China
Yuan-Li Yang: CABR Testing Center Co. Ltd., China Academy of Building Research, No. 30, North 3rd Ring East Road, Beijing, 10013, China
Abstract
In recent years, with the breakthroughs in key technologies for the preparation and pumping of Ultra-High Performance Concrete (UHPC), the H-section steel-UHPC composite structures have been increasingly applied in large-scale engineering projects subjected to complex conditions such as heavy loads, strong earthquakes, and explosion impacts. To fully exploit the collaborative performance of steel and UHPC, the study investigated the effects of Ultra-High Performance Concrete (UHPC) strength, steel fiber volume fraction, the embedded length of the steel section, and loading schemes (monotonic and cyclic) on the interfacial bond performance using 18 H-section steel-UHPC composite specimens. Failure modes and crack development were analyzed through load-slip curves. The results indicated that concrete strength, steel fiber volume fraction, and the embedded length of the steel section significantly influenced both peak bond stress and residual bond stress. Meanwhile, the loading scheme had a smaller effect on peak bond stress but a more pronounced effect on residual bond stress. Under cyclic loading, peak bond stress decreased by 7% to 15% compared to monotonic loading, while residual bond stress decreased by 16% to 57%. Additionally, a formula was developed to characterize the bond strength between H-shaped steel and UHPC, considering different loading schemes. Finally, the bond composition of the interface was analyzed, establishing relationships between the interfacial chemical bond ratio and factors including steel embedded length, steel fiber volume fraction, and UHPC strength based on the experimental data.
Key Words
bond-slip; characteristic bond strength; cyclic loading; H-section steel; ultra-high performance concrete
Address
Shiyu Tang, Wei Huang, Bo Wang: Hubei Key Laboratory of Mechanics Theory and Application New Materials, Hubei, Wuhan University of Technology, Wuhan 430070, China
Zhi Zhou: School of Transportation and Logistics Engineering, Hubei, Wuhan University of Technology, Wuhan 430070, China
Abstract
The seismic performance of the beam-to-column connections is improved by creating inelastic behavior away from the face of the column. This paper presents a numerical assessment of an innovative ductile connection known as the Tubular Flange Beam (TFB) connection, utilizing the Abaqus finite element software. The TFB connection entails the substitution of a section of the beam with two tubes. In this study, 23 models, consisting of initial and parametric variety models are proposed and their impact on the moment–rotation behavior and plastic strain distribution of the connections is investigated under monotonic and cyclic loadings. The parameters consist of the tubes distance from the column, the length and section size of the beam and column, as well as the diameter and thickness of the tubes. The results demonstrated that changes in the tubes geometry had significant effects on the elastic stiffness and plastic moment capacity of the connection. Moreover, the effect of column size and length changes on the connection behavior was insignificant. Also, as the strength of the connection materials increased, the plastic moment capacity of the connection decreased, while the elastic stiffness of the connection did not change much. In addition, the TFB connection in comparison with the RBS and traditional welded beam to column connections has consistent hysteresis curve and effectively concentrates plastic strains within the reduced zone.
Key Words
finite element analysis; monotonic and cyclic loading; reduced beam section; steel moment resisting frame;
tubular flange beam
Address
Ramin Naseri and Payam Ashtari: Department of Civil Engineering, University of Zanjan, Iran
Abstract
This paper investigates the fundamental frequency analysis of Axially Functionally Graded Graphene Platelets Reinforced Composite (AFG-GPLRC) beams in thermal environments. The graphene platelets are dispersed in five different patterns (UD, AFG-X, O, A, V) along the axis, either uniformly or non-uniformly. The effective material properties are determined using an improved Halpin-Tsai micromechanical model and the Rule of mixture. The governing equation, derived from the Euler-Bernoulli beam theory, is solved using the weighted residue method (Galerkin's method) to obtain element matrices. The accuracy of the analysis is confirmed by comparing the results with existing solutions. A comprehensive parametric study is conducted to investigate the impact of distribution patterns, graphene content, geometric parameters, and temperature changes on the free vibration behaviour of AFG-GPLRC beams. Due to the low graphene content used, the thermal properties of AFG-GPLRC were not significantly affected, and a significant decrease in the fundamental natural frequency was observed when the beam underwent a temperature change. This effect was consistent regardless of the boundary condition and distribution pattern.
Address
Amit Kumar Gantayat, Sudhir Kumar Yadav, Mihir Kumar Sutar and Sarojrani Pattnaik: Mechanical Engineering Department, Veer Surendra Sai University of Technology Burla, India
Abstract
As an effective measure to reduce the internal force of long-span soil-steel structures under live load, the relieving slab is widely used in soil-steel structures where the cover depth can't meet the code's requirements. However, the effect and mechanism of the relieving slab and the calculation method for the internal force of soil-steel structures with relieving slabs are not yet clear. Therefore, loading tests were carried out on the model culvert with or without the relieving slab in this paper. The influence of the geometric parameters of the relieving slab and cross-section shape on the effect and the mechanism of the relieving slab were analyzed through the finite element models (FEMs) verified based on the test data. The calculation methods of the dispersion angle and the equivalent thickness of the relieving slab were fitted according to the parameter analysis results. The results show that the relieving slab spreads the live load to a larger range and prevents soil failure. The deformation and
stresses are reduced by up to 86% and 73%, respectively. The calculation method proposed in this paper is more accurate and safer than the method proposed by Bakht and Abdel-Sayed.
Key Words
finite element model; live load dispersion; loading tests; relieving slab; soil-steel structures
Address
Baodong Liu, Fei Wu, Wangqi Chen: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
Lei Yao: Guangxi Dapu Highway Co. Ltd., Qinzhou 535400, China
Zhihong Wang: Hengshui Yitong Pipe Industry Co. Ltd., Hengshui 053000, China
open access
