Abstract
The need for carbon neutrality in the world strives the construction industry to reduce the use of construction
materials. Aiming to this, recycled aggregate concrete (RAC) could be used as it reduces the carbon dioxide emissions.
Currently, RAC is mainly used in non-structural members of civil constructions, seldom used in structural members. To broaden
its structural use, a new type of composite column, i.e., the square and rectangular RAC filled FRP tubes (CFFTs), has been
concerned in this study. The investigation on their axial compressive behavior through physical test and numerical analysis
demonstrated that the load-carrying capacity of such column is reduced with the increase of replacement ratio of recycled
aggregate and aspect ratio of section but can be improved by the increase of FRP confining stiffness and corner radius, said
capacity can be equivalent to their steel reinforced concrete counterparts. At failure, the hoop strain at corner of tube is
unexpectedly smaller than that at flat side of the tube although the FRP tube ruptured at its corner first, revealing a premature
failure. Besides, a design-oriented stress-strain model of concrete and an analysis-oriented finite element model are proposed to
predict the load-strain response of square and rectangular CFFT columns, which facilitates the engineering use of RAC in loadcarrying structural members.
Key Words
compression; design model; finite element model; FRP; recycled aggregate concrete; square and rectangular
Address
Ming-Xiang Xiong:Earthquake Engineering Research & Test Center, Guangzhou University, Guangzhou 510405, China
Xuchi Chen:Guangzhou Second Municipal Engineering Co., Ltd., Guangzhou 510060, China
Fengming Ren:School of Civil Engineering, Guangzhou University, Guangzhou 510006, China
Abstract
Geological hazards in landslide is one of the most extensive and destructive phenomena are among natural disasters.
According to the topography high mountains, tectonic activity, high seismicity, diverse conditions Geology and climate,
basically China to create a wide spectrum of landslides have natural conditions and these landslides are annual. They cause a lot
of financial losses to the country. It is very difficult to predict the time of the landslide, hence the identification landslide
sensitive areas and zoning of these areas based on the potential risk is very important. Therefore, it should be susceptible areas
landslides should be identified in order to reduce damages caused by landslides find. the main purpose of landslide sensitivity
analysis is identification high-risk areas and as a result, reducing damages caused by landslides It is the way of appropriate
actions.
Key Words
fuzzy logic methods; geological hazards; hierarchical analysis; landslides
Address
Shasha Yang:School of Petroleum Engineering and Environmental Engineering, Yan
Abstract
The number of studies investigating the response of concrete-filled tubes (CFTs) under shear has been very limited
in the literature. This lack of research has been traditionally reflected in international design standards as rather conservative
shear strength predictions for CFTs. The dearth of research on the shear response is even more pronounced for the case of
concrete-filled stainless steel tubes (CFSSTs). In line with this, the present study investigates the shear response of circular and
square CFSSTs using advanced finite element (FE) analysis. A thorough review of the previous studies on the shear response of
carbon steel CFTs is provided along with a summary of past experimental programmes as well as the developed and codified
design methods. A comprehensive numerical study is then conducted considering a wide range of circular and square, austenitic
and lean duplex CFSSTs with different concrete infills and shear span-to-depth ratios. The effect of the tail length on the shear
response is investigated and the minimum required tail length for achieving full shear capacity is established. The simulations
are also used to highlight the importance of the dilation of the concrete core in the shear response of concrete-filled tubes and its
relationship with the utilised boundary conditions. Furthermore, the numerical results are compared in detail with the predictions
of design approaches developed previously for carbon steel CFTs and their accuracy and applicability to the stainless steel
counterpart are demonstrated and recommendations are made accordingly.
Key Words
CFSST; concrete-filled; design; finite element analysis; shear; stainless steel
Address
Sina Kazemzadeh Azad and Brian Uy:School of Civil Engineering, The University of Sydney, NSW 2006, Australia
Abstract
Composite dowels are implemented as a powerful alternative to headed studs for the efficient combination of Ultra
High-Performance Concrete (UHPC) with high-strength steel in novel composite structures. They are required to provide
sufficient shear resistance and ensure the transmission of tensile forces in the composite connection in order to prevent lifting of
the concrete slab. In this paper, the load bearing capacity of puzzle-shaped and clothoidal-shaped dowels encased in UHPC
specimen were investigated based on validated experimental test data. Considering the influence of the embedment depth and
the spacing width of shear dowels, the characteristics of UHPC square plate on the load bearing capacity of composite structure,
240 numeric models have been constructed and analyzed. Three artificial intelligence approaches have been implemented to
learn the discipline from collected experimental data and then make prediction, which includes Artificial Neural NetworkParticle Swarm Optimization (ANN-PSO), Adaptive Neuro-Fuzzy Inference System (ANFIS) and an Extreme Learning
Machine (ELM). Among the factors, the embedment depth of composite dowel is proved to be the most influential parameter on
the load bearing capacity. Furthermore, the results of the prediction models reveal that ELM is capable to achieve more accurate
prediction.
Address
Zhihua Xiong:1)College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi, China
2)nstitute of Steel Construction, RWTH Aachen University, Aachen, Germany
Zhuoxi Liang, Xuyao Liu and Jiawen Li:College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi, China
Markus Feldmann:College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi, China
Abstract
This study investigates the effect of bolt preloading on the rotational stiffness of stainless steel end-plate
connections. An experimental programme incorporating 11 full-scale joint specimens are carried out comparing the behaviours
of fully pre-tensioned (PT) and snug-tightened (ST) flush/extended end-plate connections, made of austenitic or lean duplex
stainless steels. It is observed from the tests that the presence of bolt preloading leads to a significant increase in the rotational
stiffness. A parallel finite element analysis (FEA) validated against the test results demonstrates that the geometric imperfection
of end-plate has a strong influence on the moment-rotation response of preloaded end-plate connections, which is crucial to
explain the observed "two-stage" behaviour of these connections. Based on the data obtained from the tests and FE parametric
study, the performance of the Eurocode 3 predictive model is evaluated, which exhibits a significant deviation in predicting the
rotational stiffness of stainless steel end-plate connections. A modified bi-linear model, which incorporates three key properties,
is therefore proposed to enable a better prediction. Finally, the effect of bolt preloading is demonstrated at the system (structure)
level considering the serviceability of semi-continuous stainless steel beams with end-plate connections
Abstract
The present research reports the application of engineered cementitious composites (ECC) as an alternative to
conventional concrete to improve the seismic behavior of short columns. Experimental and finite element investigation was
conducted by testing five reinforced engineered cementitious composite (RECC) concrete columns (half-scale specimens) and
one control reinforced concrete (RC) specimen for different shear-span and transverse reinforcement ratios under cyclic lateral
loads. RECC specimens with higher shear-span and transverse reinforcement ratios demonstrated a significant effect on the
column lateral load behavior by improving ductility (〉5), energy dissipation capacity (1.2 to 4.1 times RC specimen), gradual
strength degradation (ultimate drift 〉3.4%), and altering the failure mode. The self-confinement effect of ECC fibers maintained
the integrity in the post-peak region and reserved the transmission of stress through fibers without noticeable degradation in
strength. Finite element modeling of RECC specimens under monotonic incremental loads was carried out by adopting
simplified constitutive material models. It was apprehended that the model simulated the global response (strength and stiffness)
and damage crack patterns reasonably well.
Key Words
Engineered cementitious composites (ECC); finite element model; seismic behavior; short columns
Address
Syed Humayun Basha, Xiaoqin Lian, Wei Hou, Pandeng Zheng and ZiXiong Guo:College of Civil Engineering, Huaqiao University, Xiamen 361021, China
Abstract
This paper introduces a novel approach to multi-material topology optimization (MTO) targeting in-plane bidirectional functionally graded (IBFG) non-uniform thickness Reissner-Mindlin plates, employing an alternative active phase
approach. The mathematical formulation integrates a first shear deformation theory (FSDT) to address compliance minimization
as the objective function. Through an alternating active-phase algorithm in conjunction with the block Gauss-Seidel method, the
study transforms a multi-phase topology optimization challenge with multi-volume fraction constraints into multiple binary
phase sub-problems, each with a single volume fraction constraint. The investigation focuses on IBFG materials that incorporate
adequate local bulk and shear moduli to enhance the precision of material interactions. Furthermore, the well-established mixed
interpolation of tensorial components 4-node elements (MITC4) is harnessed to tackle shear-locking issues inherent in thin plate
models. The study meticulously presents detailed mathematical formulations for IBFG plates in the MTO framework,
underscored by numerous numerical examples demonstrating the method's efficiency and reliability.
Abstract
To avoid debonding failure, a novel type of hybrid anchorage (HA) is proposed in this study that uses a slotted plate
to lock the ends of the fiber-reinforced polymer (FRP) sheet in addition to the usual bonding over the substrate of the
strengthened member. An experimental investigation was performed on three groups of RC beams, which differed from one
another in either concrete strength or steel reinforcement ratio. The test results indicate that the end self-locking of the CFRP
sheet can improve the failure ductility, ultimate capacity of the beams and its utilization ratio. Although intermediate debonding
occurred in all the strengthened beams, it was not a fatal mode of failure for the three specimens with end anchorage. Among
them, FRP rupture occurred in the beam with higher concrete strength and lower steel reinforcement ratio, whereas the other two
failed by concrete crushing. The beam strengthened by HA obtained a relatively high percentage of increase in ultimate capacity
when the rebar ratio or concrete strength decreased. The expressions in the literature were inspected to calculate the critical loads
at intermediate debonding, FRP rupturing and concrete crushing after debonding for the strengthened beam. Then, the necessity
of further research is addressed.
Address
Chaoyang Zhou,Xuejun He and Yi Wang:1)National Engineering Research Center of High-speed Railway Construction Technology, Central South University, Changsha 410075, China
2)School of Civil Engineering, Central South University, Changsha, Hunan 410075, China
Yanan Yu and Chengfeng Zhou:National Engineering Research Center of High-speed Railway Construction Technology, Central South University, Changsha 410075, China
