Tengfei Xu

• Ph.D.
• Professor (Full) at Southwest Jiaotong University

Base-isolated structures can effectively control structural response, of which rubber bearings are key components. To ensure the proper functioning of rubber bearings, it is important to accurately detect their state. In previous studies, a smart rubber bearing has been proposed to monitor the axial pressure, shear deformation, and rupture damage o...

This paper provides an experimental and analytical investigation on the bond behavior of reinforcing bars embedded in ultra-high performance concrete (UHPC) via a series of pullout tests. The local bond stress-slip relationship and global bond slip behavior were tested using specimens with embedment lengths of 2 , 5 , and 7 , where is the diameter...

This paper proposed a new method of exposing fibers using expandable polyethylene (EPE) foam to improve the interface performance. The flexural tensile behavior of the interface between precast steam-cured and cast-in-place non-steam-cured ultra-high performance concrete (UHPC) members was examined under four-point bending. The improvement effects...

The tensile creep of concrete with supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) is investigated in this paper. A total of 21 series of tensile creep tests using dog‐bone specimens under uniaxial tensile loading have been carried out. The cement replacement rates considered were 30...

The damage of non-steam-cured ultra-high performance concrete (UHPC) under short-term sustained compression was experimentally investigated. The UHPC specimens were tested under monotonic loading, cyclic loading without a sustained loading history, or cyclic loading with a sustained loading history. The influence of the sustained stress levels and...

Concrete structures may experience unexpected cracking at an early age. Early age cracking can be induced by restrained deformations where tensile stress generated in concrete exceeds its tensile strength. The restrained concrete ring test is often used to evaluate the ability of concrete to resist early age cracking induced by shrinkage. This pape...

This paper proposes a novel twin-column pier with a steel shear link (SSL) installed in the cap beam to reduce seismic damage in the transverse direction. The SSL interrupts the rigid cap beam and relieves the coupled deformation of the two columns. Benefits of the yieldable SSL in the event of a strong earthquake are the longer effective deformati...

A nonlocal damage-based model is proposed to predict the nonlinear long-term deformation of concrete structures, which couples the localizing gradient-enhanced damage (LGED) model for crack nucleation and propagation to the extended microprestress-solidification (XMPS) theory for creep and shrinkage deformations. The proposed LGED-XMPS model circum...

The ageing coefficient is required in the age-adjusted effective modulus method to assess the effect of creep in concrete structures subjected to varied stress history. In this paper, experiments were carried out to calibrate the ageing coefficient for early age tensile creep of blended slag and low calcium fly ash geopolymer concrete. The developm...

The spatially curved urban flyover may deliver different seismic response with the straight plain bridge owing to its unsymmetrical structures. This paper carried out a seismic fragility analysis on a representative spatially curved flyover, composed of one curved segment and two straight segments. Twenty-two ground motions at five intensities and...

Rehabilitation scaffolding attached to an operating bridge always vibrates during construction works. Hence, individuals working on the scaffold may feel uncomfortable from exposure to excessive vibration. This paper proposes a strategy to assess the comfort of the scaffold with regard to the train-bridge-scaffold coupling vibration. Thereby, the d...

This paper focuses on the effect of supplementary cementitious materials on early-age mechanical and viscoelastic properties of concrete, restrained shrinkage-induced cracking, and time to cracking. Compressive strength, indirect tensile strength, and the elastic modulus were measured with different percentage of ordinary portland cement (OPC) repl...

This paper describes the development of an effective stress-strain relationship model for grouted sleeve connections. The transverse pressure influence has been calibrated by using the local bond stress-slip experiment including the effect of the initial construction error of the reinforcing bar. Then, the proposed effective stress-strain model was...

Mega bridges require maintenance after long-term service. Exterior hanging scaffolds are widely employed to ensure that traffic is not disrupted during the construction. The working platform, composed of the light steel beam and wooden plane, is usually eccentrically hanged under the deck. Additional horizontal support fixed on the girder is needed...

In this paper, experimental tests were carried out in order to measure early-age shrinkage and tensile creep of geopolymer concrete and assess their influence on early age cracking in reinforced concrete members. Two mixes of geopolymer concrete were tested. For the first mix, the specimens were heat-cured at a temperature of either 60 °C or 90 °C....

A concrete mix (FNS25) including 50% natural sand replacement by ferronickel slag (FNS) sand and 25% ordinary portland cement (OPC) substitution by fly ash (FA) was considered to mitigate the risk of early-age cracking in fly ash blended cement-based concrete. Experiments were carried out to accurately quantify early-age shrinkage and tensile creep...

Grouted-sleeve connections are widely used to connect prefabricated concrete members. The bond stress-slip behavior is an essential issue to be considered when assessing the performance of a grouted-sleeve connection loaded in tension. This paper presents an experimental investigation regarding the local and global bond stress-slip behavior of grou...

A fully prefabricated damage-tolerant beam-to-column connection is proposed as an approach toward an earthquake-resilient steel frame. By introducing a composite steel-ultrahigh-performance concrete (UHPC) joint and friction damper, the plastic deformation becomes concentrated on the designated plastic hinge region. Thus, the damage index and area...

In order to reduce the earthquake damage and improve the resilience of frame structures, a damage tolerant steel frame was proposed in this paper. In this steel frame, the composite Ultra-High Performance Concrete (UHPC) joint and friction damper were applied at the beam to column connection. The UHPC joint can provide excellent crack resistance an...

Experiments were carried out under ambient conditions and in a temperature–humidity control room to assess the influences of early-age shrinkage and tensile creep on cracking in reinforced-concrete (RC) members subjected to internal restraint. Two concrete mixes were considered, with compressive strengths of 36 MPa and 47 MPa. The evolution of the...

Under normal in-service conditions, beams and slabs in reinforced concrete structures are usually cracked. Concrete cracking and steel-concrete bond damage lead to an irreversible reduction in the overall stiffness, thereby affecting the serviceability of reinforced concrete structures. The method proposed in this paper aims to assess both the stee...

In this article, experiments focusing at the influence of steel–concrete bond damage on the dynamic stiffness of cracked reinforced concrete beams are reported. In these experiments, the bond between concrete and reinforcing bar was damaged using appreciate flexural loads. The static stiffness of cracked reinforced concrete beam was assessed using...

Under in-service conditions, beams and slabs in reinforced concrete structures are almost always cracked, as the tensile strength of the concrete is low. Due to the irreversible reduction in overall stiffness resulting from cracking and the residual deflection after unloading, the structural response is load path dependent. In this paper, an existi...

The deformation of long-span reinforced concrete arch bridge will be increased with time because of creep and shrinkage effect. Particularly in the case of the concrete bridge constructed with stiffening frame technique, the time-variant effects caused by shrinkage and creep may be extremely complicated. Therefore, reasonable prediction of the time...

Tension stiffening affects the strain distribution along the tensile reinforcement in a cracked reinforced concrete beam and in the tensile concrete between cracks. It also affects the overall stiffness and hence the deflection of the beam. In this paper, the results of experiments on eleven reinforced concrete beams with reinforcement ratios betwe...

This paper presents a modified topological vulnerability analysis for the metro network. The flow impacts and the capacity constraint are taken into account in this work. A node-based congestion is considered in the travel time model for the metro network. The logit-based path choice model is adopted to assign the flow in the network. Based on the...

The long-term deformation prediction method based on Bayesian theory for concrete structures becomes weak when the prediction work should be carried out before the structure being constructed. Because there is no measured value of short-term deformation to build the likelihood function, and the standard deviation of the short-term deformation, an i...

In this paper, a model, initially developed to calculate the stiffness of cracked reinforced concrete beams under static loading, is used to assess the dynamic stiffness. The model allows calculating the average inertia of cracked beams by taking into account the effect of bending cracks (primary cracks) and steel-concrete bond damage (i.e. interfa...

To investigate the random deformation of the in-service prestressed reinforced concrete beam, full-scale loading tests of three prestressed reinforced concrete simply supported beams for highway with the span of 30 m were performed. With Monte-Carlo simulation and nonlinear finite element method, the stochastic analysis model on nonlinear deformati...

Combining Monte Carlo sampling with nonlinear finite element method, the random analysis model for nonlinear deflection of reinforced concrete beams was established to assess the random deflection of in-service reinforced concrete beams. Based on this model, the stochastic deflection of the classic concrete beam in loading process was simulated. Me...

A piecewise response surface is suggested to reduce the error from the unsmooth response surface caused by the cracking of a reinforced concrete beam, by replacing the traditional single smooth response surface. The stochastic analysis model for the time-variant deflection of a reinforced concrete beam is performed with GL2000 model and nonlinear f...

Significant computational cost can be saved by using a hybrid method combining Monte Carlo (MC) method with a response surface in stochastic simulation. However, when the applied load is close to the cracking load, it can be found that the real deflection response of a reinforced concrete (RC) beam may not be smooth. In this case, the traditional r...

Steel-concrete composite girder is consisted of concrete slab and steel girder through shear connectors. Owing to shrinkage and creep of concrete, redistribution of structural internal force and stress should be caused. It is widely accepted that shrinkage and creep of concrete possess large randomness, which may induce the stochastic long-term str...

Most of the previous research on concrete-filled steel tube is restricted to a deterministic approach. To gain clear insight into the random properties of circular concrete-filled steel tube, reliability analysis is carried out in the present study. To obtain the structural nonlinear response and ultimate resistance capacity, material and geometric...

For long-span reinforced concrete arch bridges constructed with the stiffening frame technique, the long-term effect caused by creep and shrinkage may be extremely sophisticated. Owing to the stochastic properties of creep and shrinkage, the long-term variation of stresses exhibits significant uncertainty. For such large-scale structures as long-sp...

Owing to the randomness of shrinkage and creep of concrete, random analysis method should be adopted to give a reasonable result with probabilistic guarantee. Stochastic variables for long-term analysis with GL2000 model about creep and shrinkage of concrete were presented. Combining Monte Carlo sampling with the response surface method, the stocha...

Most of the previous research on concrete-filled steel tube is restricted to a deterministic approach. To gain clear insight into the random properties of circular concrete-filled steel tube, reliability analysis is carried out in the present study. To obtain the structural nonlinear response and ultimate resistance capacity, material and geometric...

Most of the previous researches on the concrete-filled steel tube are restricted to deterministic approach. To give a clearer insight about random properties of circular concrete-filled steel tube, reliability analysis is carried in the present study. Material and geometrical nonlinear analysis of a circular concrete-filled steel tube is performed...

To deal with the contradiction between accuracy and time consuming, based on the response surface and nonlinear finite element method, model of reliability analysis of CFT is present for engineering application. Initial geometric imperfection is induced by consistent mode imperfection method. The reliability index of CFT arch and CFT high piers are...

For high-rise or long-span structures, geometrical nonlinear effect should never be neglected. The structural behaviors of slender concrete-filled steel tube column with coupled action of geometrical and material nonlinearity are investigated with degenerated beam element. Owing to utilizing the strain-displacement relationships of 3D structures, a...

A model study on high-pier made of concrete filled steel tube laced columns has been finished, which was based on the real bridge. A large scaled model was put up because of the high-pier is one of the middle piers of the continuous rigid frame bridge and the girder is in the curve. The main parameters were concrete degree (C80) and the steel yield...

Steel-concrete composite girder is consisted of concrete slab and steel girder connected through shear connectors. Owing to shrinkage and creep of concrete, redistribution of structural internal force and stress should be caused. It is widely accepted that shrinkage and creep models of concrete possess large randomness. The influences of stochastic...

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on...

To deal with the contradiction between accuracy and time consuming, a model of reliability analysis of CFT was proposed based on the response surface and nonlinear finite element method, And Initial geometric imperfection was induced by consistent mode imperfection method. The reliability index and sensitivity coefficients of CFT high piers were in...

Three dimensional coupled bending-torsion dynamic vibrations of thin-walled open section beam subjected to moving vehicle are investigated by transfer matrix method. Through adopting the idea of Newmark-β method, the partial differential equations of structural vibration can be transformed to the differential equations. Then, those differential equ...

Three dimensional coupled bending-torsion dynamic vibrations of thin-walled open section beam subjected to moving vehicle are investigated by transfer matrix method. Through adopting the idea of Newmark- method, the partial differential equations of structural vibration can be transformed to the differential equations. Then, those differential equa...

The traditional increment dynamic analysis (IDA) method gave larger acceleration response than that by nonlinear static pushover (SPO) analysis. The inelastic response spectrum is used as an intensity magnitude, and the yield strength factors are continuously changed with the different seismic intensities. So the modified IDA meth-od is suggested,...

The differential equation for the natural vibration of Euler-Bernoulli beam with continuously varying cross-section, in consideration of axially acted force and its mass distribution is derived, and the series analytical solution is obtained by the Frobenius method. Introducing boundary conditions, the natural frequencies and modal solutions are co...

The reliability of vehicle–bridge dynamic interaction is evaluated. A time domain transfer matrix method for dynamic analysis is proposed. Using the idea of the Newmark-\beta method, the partial differential equation of beam vibration is transformed into a differential equation. Then, this differential equation is solved by the transfer matrix meth...