Zhi Fang

Hunan University · College of Civil Engineering

Ultra-high-performance concrete (UHPC) holds great promise for constructing lightweight and high-performance concrete structures. Hence, the proportion of live load increases, in turn, leads to a higher live-to-dead load ratio. UHPC structures suffer from cyclic stress amplitude in higher possibility. Therefore, the behavior and constitutive model...

The paper presents a numerical investigation of the cyclic behavior of ultra-high-performance concrete (UHPC) shear walls with hybrid reinforcement of fiber-reinforced polymer (FRP) and steel bars. The concrete damage plasticity (CDP) model in ABAQUS was used to establish the finite-element analysis (FEA) model. The numerical results were compared...

To investigate the bond behavior of an ultra-high performance concrete (UHPC)-filled bond-type anchorage for carbon fiber-reinforced polymer (CFRP) tendons, both static tensile tests and impact tests were performed on 20 groups of specimens. The anchorages with embedded lengths of 50, 100, 150 and 200 mm were subjected to the static tension and lon...

To fully understand the fire resistant performance of Carbon fiber reinforced polymer (CFRP) cable with high-temperature-resistant resin matrix, both steady state and fire resistant tests were conducted on specimens. The degradation law for axial tensile properties of CFRP cable without pre-tension load under high temperature from 100 to 600 °C was...

Steel fiber is the main reinforcing fiber of ultra-high performance concrete (UHPC) and could greatly improve its tensile strength and toughness. As a result, steel fiber has a significant influence on the structural behavior of UHPC beams under pure torsion. However, related research in this regard is severely insufficient. To fill in this researc...

This paper investigates the usage of a thin layer of Ultra-high performance concrete (UHPC) reinforcing the concrete decks at the hogging moment region of steel–concrete composite beam bridges. An integrated experimental and numerical study was conducted to assess the influence of several parameters, such as the type of overlay concrete, arrangemen...

This paper proposes a prefabricated steel–ultra-high-performance concrete (UHPC) composite deck (PSUCD) system equipped with notched perfobond strips (NPBLs) for long-span cable-stayed bridges. Compared with the use of an ultra-thin UHPC overlay, the proposed deck system better leverages the high compressive strength of the UHPC. Seven full-scale c...

Fatigue-induced deterioration has played an important role in governing the reliability of modern concrete structures, such as wind turbines, highway pavements, and high-speed railway bridges. Although the fatigue of concrete gains increasing attention, a thorough understanding of its mechanism is still lacking, and an accurate model for the predic...

The present study explored potential forms of impact protection for carbon fiber-reinforced polymer (CFRP) tendons. Charpy impact tests were performed on CFRP rods and strands under protections of polyvinyl chloride (PVC) and poly-ethylen (PE). In the experimental program, the impact damage pattern and absorbed energy of CFRP tendons with and witho...

This paper presents an experimental investigation of the fatigue behavior of ultrahigh-performance concrete (UHPC) beams prestressed with external carbon fiber-reinforced polymer (CFRP) tendons. Seven T-shaped beams were tested, and the effects of the effective prestressing stress, partial prestressing ratio, and fatigue load level on the flexural...

The lap behavior of Carbon Fiber Reinforced Polymer (CFRP) indented bars in Ultra-High Performance Concrete (UHPC) were investigated based on pullout test under direct tension on 27 specimens in total. The test variables include splice length, UHPC strength and stirrup ratio. The lap failure mechanism of CFRP bar embedded in UHPC and the influence...

In order to fully investigate the relaxation behavior of carbon fiber reinforced polymer (CFRP) cable exposed to high temperature, both steady state-constant displacement and temperature (ST-CDT), and transient state-constant displacement and temperature (TR-CDT) tests were conducted on specimens. The failure modes, stress loss laws and rupture tim...

Both steady state-constant load and temperature (ST-CLT), and transient state-constant load and temperature (TR-CLT) tests were conducted on carbon fiber reinforced polymer (CFRP) cable in order to investigate the corresponding high-temperature creep behavior. The failure modes, creep strains and rupture times of CFRP cables exposed to high tempera...

This paper presents a comprehensive study on the cyclic behavior of ultra-high-performance concrete (UHPC) shear walls with different axial-load ratio. A total of four full-scale UHPC shear walls with a test axial-load ratio of 0.1, 0.3, 0.35 and 0.4 were tested. The seismic behavior of UHPC shear walls was evaluated, and the influences of the axia...

A new kind of structural system, ultrahigh-performance concrete (UHPC) shear walls reinforced with carbon fiber–reinforced polymer (CFRP) and steel bars, is proposed in this study. CFRP bars were used in the web region of the shear walls to obtain favorable self-centering capacity, and steel bars in the boundary element were used to achieve high en...

To solve the cracking and interface debonding problems of ultra-high-performance concrete (UHPC) induced by high shrinkage in confined spaces or under strongly restrained conditions, a series of laboratory experiments was performed to evaluate the use of a CaO-based expansive agent (EA) in combination with a super absorbent polymer (SAP) and/or a s...

The group effect on the shear capacity of perfobond strip (PBL) connector group embedded in ultrahigh performance concrete (UHPC) in the steel–concrete joints of hybrid structures was studied experimentally. Push-out tests were performed on 26 encased PBL specimens parameterized by the concrete type, row (or hole) number, and row spacing of connect...

In the present paper, a comprehensive study on the flexural fatigue behavior of ultra-high-performance concrete (UHPC) beams prestressed with carbon-fiber-reinforced polymer (CFRP) tendons is reported. A total of two UHPC beams prestressed with CFRP tendons were experimentally investigated. On the basis of the fatigue constitutive model of the mate...

The ultra-high-performance concrete (UHPC) and fiber-reinforced polymer (FRP) are well-accepted high-performance materials in the field of civil engineering. The combination of these advanced materials could contribute to improvement of structural performance and corrosion resistance. Unfortunately, only limited studies are available for shear beha...

This paper presents an experimental investigation on the flexural behavior of ultra-high-performance concrete (UHPC) beams prestressed with external carbon fiber-reinforced polymer (CFRP) tendons. A total of eight T-shaped beam specimens were fabricated and tested, and the effects of the effective prestressing stress, partial prestressing ratio, de...

The pure mode-II fracture behavior of an adhesively bonded glass fiber reinforced polymer (GFRP)/steel joint was experimentally investigated using a four-point end-notched flexure (4ENF) test. Cracking of the 4ENF specimen initiated and propagated in the adhesive-steel surface. The dominant failure mode observed in all specimens was adhesive-steel...

The use of an innovative type of perfobond rib (PBL) shear connector in steel–concrete joints of hybrid girder bridges has gained wide popularity among bridge engineers. For a PBL group with multi-row PBLs in tandem arrays, comprehensive interactions exist among the connectors. However, the current design approaches assume that the force transferre...

To elucidate the influence of the stirrup ratio and steel fiber content on the seismic behavior of ultra-high-performance concrete (UHPC) columns, five full-scale UHPC columns with different stirrup ratios (0%, 0.25%, and 0.5%), and steel fiber volume ratios (0%, 1%, and 2%) were tested, and the effects of the stirrup and steel fiber volume ratios...

A new type of reinforced concrete column with ultra-high-performance concrete (UHPC) and hybrid carbon fibre-reinforced polymer (CFRP) and steel bars is proposed in this paper. The CFRP bars with an excellent linear elastic property are used in the columns to enable the expected self-centring capacity. Steel bars with good plastic properties and hi...

The current study experimentally investigated the influence of elevated-temperature exposure on the mechanical performance of carbon fiber reinforced polymer (CFRP) wires through conducting the axial tensile, three-point bending and transverse load tests. The results show that the CFRP wires under axial tensile load exhibited a brittle fracture aft...

Ultra-high performance concrete (UHPC) is a type of cementitious composite, and demonstrates very high compressive strength and good ductility. The favorable ductility and energy dissipation capacity of UHPC material make it possible to achieve excellent seismic performance in all kinds of structural members. The paper reviewed the recent progress...

This study investigated the mechanical behavior of carbon fiber reinforced polymer (CFRP) wires subjected to combined tension and bending through transverse load tests and finite element analysis (FEA). The properties of the CFRP wires were examined through axial tensile and three-point bending tests. Transverse static load tests were conducted on...

To provide a safe and reliable connection using bolts for glass fibre-reinforced polymer (GFRP)/metal hybrid structures in civil engineering, the static and fatigue behaviours of a bolted GFRP/steel double-lap joint (DLJ) with a clamping force of 10 N m were investigated experimentally under monotonic tensile loading and repetitive tensile loading...

Keywords: Adhesively-bonded composite/steel joint Mixed-mode fracture behavior 4SLB specimen Power law criteria A B S T R A C T The pure mode-I, pure mode-II and the mixed-mode I/II fracture behavior of the adhesively-bonded pultruded GFRP/steel joint were experimentally investigated by using double cantilever beam (DCB) test, and four-point end-no...

A comprehensive study on the fatigue behavior of stirrup free reactive powder concrete (RPC) beams prestressed with carbon fiber-reinforced polymer (CFRP) tendons is presented in this paper. A total of six specimens were tested, and the effects of the shear span/depth ratio, load amplitude, and steel fiber content on the fatigue behavior of the bea...

The experimental investigation of mixed-mode I/II fracture behavior for the adhesively-bonded pultruded GFRP joint was performed with the four-point single leg bending (4SLB) test. Cracks initiated and propagated in mat layer of the pultruded GFRP laminate for 4SLB specimens with three different thicknesses of upper adherend. The compliances of 4SL...

The fatigue behavior of an adhesively bonded glass fiber-reinforced polymer (GFRP)/steel double-lap joint (DLJ) under cyclic tensile loading with load ratio R = 0.1 was experimentally studied. Results in terms of failure mode, F-N curve, stiffness degradation law, crack initiation and propagation laws were obtained. Linear and nonlinear models of s...

A concrete-filled steel cell (CFSC) is commonly used in steel-concrete joints of hybrid girders. The performance of shear connectors embedded in CFSCs has been investigated in the current study in which a series of push-out tests were performed in order to assess the mechanical behavior of a perfobond strip connector (PBL) and headed steel studs. T...

To study the structural response of a long-span cable-stayed bridge to cable loss during construction, the static performance of the Chishi Bridge subjected to multiple-cable loss caused by a fire accident was investigated in detail by field inspection and finite-element simulation. Nine cables on the same cable plane ruptured successively during t...

This paper experimentally investigated the effect of temperature on the transverse impact response of preloaded carbon fiber reinforced polymer (CFRP) wire. The CFRP wires with a glass transition temperature of 99 °C were tested in the temperature range of −40 to 80 °C using a drop-weight impact test system. The results show that the maximum impact...

Ultra-high performance concrete (UHPC) is a new building material with great application prospects in the engineering field. The material’s advantages include high strength and good durability, which can reduce the cross-sectional area of members and the weight of the structure. In order to study the shear capacity of a UHPC squat shear wall, a low...

In order to create a reinforced concrete shear wall structure with good energy dissipation and resilience，a kind of ultra-high performance concrete RPC（Reactive Powder Concrete）shear wall structure composed of ordinary reinforcement and CFRP（Carbon Fiber Reinforced Polymers）was presented. A nonlinear finite element model using nonlinear finite elem...

The transverse static performance and low-velocity impact response of individual carbon fiber–reinforced polymer (CFRP) wires were investigated experimentally in this study. First, the axial tensile properties of CFRP wires with a nominal diameter of 4.17 mm were obtained through axial tensile tests. Then transverse static tests and low-velocity im...

Due to structural deterioration, the performance of concrete bridges degrades with time and may result in catastrophic failure events, especially for nonredundant structures. This paper develops a methodology for assessing time-variant reliability and redundancy of multigirder prestressed concrete bridges at material, component, and system levels....

Ultra-high-performance concrete is typically defined as an advanced cementitious material that has a compressive strength of over 150 MPa and superior durability. This article presents the development of a new type of ultra-high-performance concrete, namely, ultra-high-performance seawater sea-sand concrete. The development of ultra-high-performanc...

In order to investigate the mechanical behavior of the steel-concrete joint with ultrahigh performance concrete (UHPC) grout in single cable-plane hybrid cable-stayed bridges, a model test with a scale of 1:3 for a hybrid girder consisting of a flat steel box girder, a prestressed concrete (PC) box girder, and a steel-concrete joint connecting the...

p>Two novel approaches are proposed in the present study to assess the damage degree of girders based on the fractal analysis of crack patterns and natural frequency. Two full scale simply‐supported prestressed concrete box girders were firstly designed and subjected to three‐point repeated load bending tests. Concrete cracking, deformation and nat...

Experimental studies and numerical simulations were carried out to assess the seismic performance of Ultra High Performance Concrete (UHPC) box piers. The mechanical performance of the specimens under constant axial load and reversed cyclic lateral load were tested at different loading conditions (different angles between applied load and the stron...

In hybrid girder bridges, an efficient type of steel-concrete joint, the so called concrete filled steel cells (CFSCs), can be used to transfer forces between the steel and concrete girders. In the CFSCs, where shear connectors embedded in the concrete core, the bearing capacity of shear connectors is significantly affected by the side confinement...

This study is aimed to determine the influence of the parameters relevant for the application of ultrasonic tomography in the field of grouting quality evaluation. The parameters tested were the wave velocity difference between concrete and grout (VDCG), the type of material used for a pipe, and the type of pre-stressed tendon within the pipe. Four...

This paper proposes a cable-stayed bridge with carbon fiber-reinforced polymer (CFRP) cables and ultra-high performance concrete (UHPC) members and presents its design and structural behavior to analyze its feasibility with a super-long span. Based on the geometrical dimensions of a real cable-stayed bridge with a steel girder and cables in additio...

In order to obtain how the elastic modulus of reactive powder concrete (RPC) is affected by the strength grade and steel fiber content, and to determine the quantitative relationship between the dynamic elastic modulus, which is measured by ultrasonic pulse method and the impact-echo method, and static modulus of elasticity that is measured by mono...

As a new generation of concrete, RPC(Reactive Powder Concrete) has attracted great research attention for its ultra-high strength and high durability. In the present paper, experimental results from tests on eight prestressed RPC I-section girders failing in shear are reported herein. The beams with RPC of 120 MPa in compression were designed to as...

Nowadays, bridge widening has become an economic option to tackle the increasing demand of the traffic volume and to enhance the capacity of existing highway bridges. Thus, relevant studies on the performance assessment of widened bridges are needed. This paper presents a computational probabilistic framework for time-variant reliability analysis o...

The vulnerable transverse behavior of the carbon-fiber-reinforced polymer/plastic (CFRP) restricts the application of CFRP cables in bridges, when considering the possible collisions from vehicles. This paper presents an experimental investigation on the transverse impact behavior of the CFRP cable system. Drop-weight impact tests were conducted on...

In order to investigate the plastic hinge length of Reactive Powder Concrete(RPC)box pier column, based on the hysteretic constitutive model, with the use of the OPENSEES secondary development platform to embed RPC material, the ductility analysis model considering reinforcement bar slippage at the foot of piers was built, in combination with Steel...

This paper aims at examining the structural behavior of perfobond strip (PBL) connectors for steel-concrete joint of hybrid girders with ultra-high performance concrete (UHPC) as grout for such connectors. Twenty-four push-out specimens fabricated according to the design used for the connectors in the steel-concrete joint in a hybrid cable-stayed b...

Research purposes: The early crack during construction stage is very widespread for large span prestressed concrete box girder bridges. These cracks which have adverse effects on the safety operation and durability for bridge, should be controlled in the construction stage. Based on the North Beach Bridge of Jingyue Yangtze River Highway Bridge, st...

To avoid the occurrence of the high hydration heat than can cause thermal cracks in the root part concrete of the main girders of long span prestressed concrete (PC) box girder bridges in the construction, the hydration heat of 3 segments of 2 long span PC box girder bridges was measured in field and at the same time, the concrete specimens of the...

In order to analyze the stress mechanism of widened bridge based on the shrinkage and creep differences between the newly-built and the existing concrete accurately, taking the lateral joint width of a simply-supported reinforced concrete slab bridge as an example, the analytical expressions of stress and displacements of the widened structure in t...

The regularities of early age tensile creep and compressive creep and theories of calculation method for creep stress are key factors for the crack prediction and prevention. Currently, the study on concrete creep focuses on matured concrete, while for early age concrete further study is still needed. The research status, test method and creep stre...

Carbon fiber–reinforced polymer/plastic (CFRP) used in bridge cables may be subjected to lateral impacts caused by vehicle collisions when in service. However, to date, few studies have been conducted on the impact behavior of CFRP cables and their anchor systems. In this paper, the impact behavior of CFRP cables was investigated through drop-weigh...

In order to develop a bond-type anchorage for the carbon fiber reinforced polymer/plastic (CFRP) strand, the bonding behavior of CFRP strand embedded in ultra-high performance reactive powder concrete (RPC) was investigated by static test. Based on the test results, the efficient anchoring modes of CFRP strands in RPC as well as the equations to ca...

The backward tracing method of the shortest path ray tracing algorithm with dynamic networks can solve the unstability problem in the backward tracing procedure of the LTI (Linear Travel-time Interpolation) algorithm, but the computational efficiency of the method is low. This study presented an improved method on backward tracing. According to the...

As a new generation of concrete, UHPC(Ultra-High Performance Concrete) has attracted great research attention for its ultra-high strength and high durability. In the present paper, experimental results from tests on eight prestressed UHPC I-section girders failing in shear are reported herein. The beams with UHPCof 120 MPa in compression were desig...

Research works related to the fiber-reinforced polymer (FRP) tendons have focused on the anchor system, but the anchor is not the only contribution to performance. Since civil structures require tendons consisting of multiple rods (e.g., cables, suspenders in bridges, or rock bolts in ground anchors), the characteristics of multirod tendons require...

With quasi-static test, the seismic behavior of three reactive powder concrete (RPC) shear walls (height-to-width ratios were 1.0, 1.5 and 2.0) was studied. The effects of height-to-width ratio on the seismic behavior such as failure mode, bearing capacity, hysteretic loops, ductility, characteristic of energy dissipation and rigidity degradation w...

Models to predict fatigue strain in concrete are critical to analysing the structural response of concrete under cyclic loading. This paper reviews existing concrete fatigue models and discusses the similarities between fatigue and creep processes. It is theoretically feasible to introduce the often-used creep models into fatigue strain predictions...

The dynamic behaviors of CFRP (Carbon Fiber Reinforced Polymer/Plastic) cable and its anchoring system under transverse impact load were investigated by testing the embossing CFRP specimens with the diameter of 9.8 mm and the anchorage assembly grouted by the RPC (Reactive Powder Concrete) using the drop hammer impact tester. Under different impact...

To investigate the mechanical performance of Perfobond shear connectors in steel-concrete joint section of hybrid girder bridge, destructive test was conducted on twenty-eight specimens that were divided into seven groups under two series, which were fabricated according to the characteristics of steel-concrete joint section of hybrid bridge. Based...

A series of compression tests were conducted on 150 groups of cement paste specimens with side lengths ranging from 40 mm to 200 mm. The specimens include cube specimens and prism specimens with height to width ratio of 2. The experiment results show that size effect exists in the cubic compressive strength and prismatic compressive strength of the...

Among those representative models on concrete shrinkage deformation prediction in the current domestic and international design codes, there exists some controversy about the effect of concrete component size and cross-sectional shape on the shrinkage deformation, thus a quantitative study about the effect is crucial to reduce the uncertainties in...

The shear behaviors of nine prestressed Reactive Powder Concrete (RPC) thin-wall box girders are investigated and the influence of some parameters, such as the shear-span to depth ratio and the stirrups ratio in bending shear zone, is analyzed. In the experiments, the crack patterns and width, load-deflection relationship, diagonal cracking behavio...

Based on the experimental values of the RPC beams prestressed with CFRP tendons of different parameters, the ductility and deformability of these beams were studied, and a corresponding parametric study of the ductility was conducted on the basis of the numerical analysis program. The research shows that the RPC beams are of better deformation capa...

Ordinary grouting slurry used in current rock anchoring systems has the problems of low bond strength and poor durability, which leads to large quantities and poor durability of underground construction works. RPC and DSP are the new-type cement matrix composites which are featured by high compressive strength, long durability and high toughness. B...

The extension & compaction scanning algorithm based on LTI (Linear Travel-time Interpolation) ray tracing algorithm can properly trace the ray path of the direct wave, diffraction wave and echo's, but it has the following problems: low computational efficiency and slow convergence speed. Aiming at these problems and using the cross-scan mode to imp...

University education is a basic stage of engineers’ cultivation. The purpose of this paper is to draw instructive conclusions by analyzing differences between Chinese and foreign universities on civil engineering undergraduate education. Teaching methods were taken into consideration. Statistical data in thirty famous universities in China, US and...

The poor performance and durability of traditional steel tendon and cement grout have become serious constraints to the development of ground anchor systems, especially when these systems are permanent features in large-scale projects such as ground anchors with capacities of more than 4,000 kN in Aizhai Bridge, China. This paper presents a large-s...

135 groups of concrete, mortar and cement prism specimens were manufactured to study the influence of aggregate mixture and strength grade on the dimensional effect of concrete uniaxial compressive behavior. The concrete strength grade included C20, C40 and C60, and the dimension of specimens included 100 mm×100 mm×200 mm, 150 mm×150 mm×300 mm and...

In order to investigate the dimensional effect of concrete cubic compressive strength, a series of compression tests were performed on 135 groups of cubic specimens with three different strength grades and three different aggregate mixtures. The strength grades of specimens included C20, C40 and C60, and the side lengths of specimen included 100 mm...

This paper presents a bond-type anchorage system for multi-rod CFRP (Carbon Fiber-Reinforced Polymer) tendons with a bonding medium of ultra-high performance RPC (Reactive Powder Concrete). A full-scale specimen of the CFRP tendon-anchorage assembly GA12-9 for nine 12.6-mm-diameter CFRP rods was made, and its behavior was studied extensively throug...

Scale effect of compressive strength of ordinary concrete and high-strength concrete were investigated through compression experiments on ordinary concrete and high-strength concrete specimens with the strength grade of C20, C40 and C60, and the specimen side length of 100, 150, 200mm. The relationship between the strength grade and scale effect wa...