Search

Background We aimed to identify the nutritional indexes, construct a prognostic model, and develop a nomogram for predicting individual survival probability in pan-cancers. Methods We collected nutritional indicators, clinicopathological characteristics, and previous major treatment details of the patients. The enrolled patients were randomly divided into training and validation cohorts. Lasso regression cross-validation was used to determine the variables to include in the cox regression model. The training cohort was used to build the prediction model, and the validation cohort was used to further verify the discrimination, calibration and clinical effectiveness of the model. Results A total of 2,020 patients were included. The median OS was 56.50 months (95% CI, 50.36–62.65 months). In the training cohort of 1,425 patients, through Lasso regression cross-validation, thirteen characteristics were included in the model. Cox proportional hazards model was developed and visualized as a nomogram. The C-indexes of the model for predicting 1-, 3-, 5- and 10-year OS were 0.848, 0.826, 0.814 and 0.799 in the training cohort and 0.851, 0.819, 0.814, and 0.801 in the validation cohort. The model showed great calibration in the two cohorts. Patients with a score of less than 274.29 had a better prognosis (training cohort: HR, 6.932; 95% CI, 5.723–8.397; log-rank P P

Steel-concrete composite structures are widely adopted in civil engineering attributed to the large span-to-depth ratio, light weight and rapid construction. However, long-term behavior of these structures attacked by environmental agents has not been fully investigated. This study presents an experimental study on monotonic and fatigue behavior of steel-concrete composite beams subjected to corrosion. Ten specimens were prepared using accelerated artificial corrosion and tested under four-point bending with a special focus on the effect of corroded studs. Different failure modes were observed for the specimens tested by static and fatigue loading. Corrosion was demonstrated detrimental effect on both monotonic load-bearing capacity and fatigue life of the specimens. The residual bending stiffness also decreased with corrosion rates.

Terbuthylazine (TBA), ametryn (AME), and atrazine (ATZ) are triazine family herbicides. They are dominantly used in the field of cereal crops like wheat and maize for prevention of upland from annual gramineous and broad-leaved weeds, with attributes of weed efficiency broad spectrum and good market performance. Salicylic acid (SA) is a kind of natural plant growth regulator existing widely in the plant kingdom and participating in many physiological and defense processes. In this study, the effects of SA on the detoxification and degradation of herbicides TBA, AME, and ATZ in maize were investigated. When maize plants were exposed to 6 mg kg–1 of the triazine herbicides, the growth and chlorophyll concentration were reduced, while the membrane permeability increased. After maize was sprayed with 5 mg kg–1 SA, the herbicide-induced phytotoxicity was significantly assuaged, with the increased content of chlorophyll and decreased cellular damage in plants. Activities of several biomarker enzymes such as SOD, POD, and GST were repressed in the presence of SA. The concentration of the triazine herbicides in maize and the soil determined by high-performance liquid chromatography was drastically reduced by spraying SA. Using LC/Q-TOF-MS/MS, six metabolites and nine conjugates of AME in maize and soil were characterized. The relative contents of AME metabolites and conjugates in maize with SA were higher than those without SA. These results suggest that SA is able to promote the detoxification and decay of these triazine herbicides in maize and soil.

Structural adhesive plays an important role in external bonding with fibre-reinforced polymer (FRP) materials for strengthening aged steel structures. The durability of structural adhesive exposed to harsh environmental conditions has attracted much attention in recent years. Extensive work has been conducted on the performance of different structural adhesives when immersed in distilled water, salt solution, alkaline solution and so on. Several prediction models for moisture absorption and mechanical behaviour degradation have been proposed based on test data. However, the effect of chloride ion has not been well understood. This paper conducted an experimental study on the durability of structural adhesive when subjected to marine environment with a special focus on the influence of chloride ion. Two types of structural adhesive were selected. A total of 256 samples were prepared and exposed to various conditions, including simulated seawater and distilled water at 35 ℃ and 50 ℃. The moisture absorption and mechanical properties degradation of adhesive were carefully monitored. Based on the experimental data, an index was developed to represent the effect of chloride ion.

OBJECTIVE To investigate the allogeneic blood transfusion (ABT) characteristics of children with acute lymphoblastic leukemia (ALL) in different risk stratification during vincristine, daunorubicin, L-asparaginase and prednisone (VDLP) induction remission. SUBJECTS AND METHODS By referring to electronic medical records, the demographic characteristics, diagnosis, test, and treatment information including ABT were collected. According to the risk stratification of the CCCG-ALL-2015 protocol, ABTs between groups were compared, and the differences were statistically analyzed. RESULTS One hundred sixty-three newly treated children with ALL were enrolled in this study, who received 643.5 U of red blood cells and 377.6 U of platelets (PLTs) during the VDLP. The amount of ABT in the intermediate-risk (IR) group (n=102) was significantly higher than that in the low-risk group (n=61), which were reflected in the red blood cells in the first half of VDLP (P=0.033) and the PLTs in the second half of VDLP (P

Injury of cervical spine is a common injury of locomotor system usually accompanied by spinal cord injury, however the injury mechanism of contusion load to the spinal cord is not clear. This study aims to investigate its injury mechanism associated with the contusion load, with different extents of spinal cord compression. A finite element model of cervical spinal cord was established and two scenarios of contusion injury loading conditions, i.e. back-to-front and front-to-back loads, were adopted. Four different compression displacements were applied to the middle section of the cervical spinal cord. The distributions of von Mises stress in middle transverse cross section were obtained from the finite element analysis. For the back-to-front loading scenario, the stress concentration was found in the area at and near the central canal and the damage may lead to the central canal syndrome from biomechanical point of view. With the front-to-back load, the maximum von Mises stress located in central canal area of gray matter when subject to 10% compression, whilst it appeared at the anterior horn when the compression increased. For the white matter, the maximum von Mises stress appeared in the area of the anterior funiculus. This leads to complicated symptoms given rise by damage to multiple locations in the cervical spinal cord. The illustrative results demonstrated the need of considering different loading scenarios in understanding the damage mechanisms of the cervical spinal cord, particularly when the loading conditions were given rise by different pathophysiological causes.

This study presents an experimental study on the static and fatigue behavior of steel-concrete composite beams subjected to negative bending moment. A total of 10 specimens were tested, with a special focus on the effect of corroded studs. The load-carrying capacity, beam stiffness and fatigue life of specimens having different corrosion rates were evaluated. Test results showed that the specimens subjected to monotonic loading failed by local buckling while fatigue loading led to shear fracture of the studs and crack initiation followed by propagation in the steel beam. Corrosion of shear connectors had a significantly detrimental effect on the load-carrying capacity and stiffness of the composite beams. As the corrosion rate increased, the fatigue life of the beams was dramatically declined by up to 29.69%. The residual bending stiffness and slip stiffness decreased as the fatigue cycles elapsed.

This paper presents a critical characterization of the uncertainty of bond strength models of adhesively bonded carbon fiber-reinforced polymer (CFRP)-to-steel joints. A model factor e was defined as the ratio of a tested ultimate load to the corresponding predicted value. A database consisted of 414 CFRP-to-steel single/double-lap shear tests was collected and two frequently used bond strength models were used in the evaluation. The statistics of e indicated a high level of both the mean value and coefficient of variation (COV). The model factor was found to be highly dependent on input parameters rather than purely random. A systematic part (f) was consequently introduced by a multiple regression analysis to remove this kind of correlation, leaving a residual lognormally distributed random variable (e*). After the critical characterization, performance of the model factor was significantly improved. Afterwards, a reliability analysis was performed to compare the model performance given the condition whether the model factor was properly considered or not. The merit of the critical calibration of the model factor is highlighted in the reliability analysis. The resistance factor for the two bond strength models was calibrated given a target reliability index βT of 3.5. The sensitivity analysis indicated that the adhesive tensile strength is the most influential parameter to the reliability index among all the input parameters.

This paper investigates the preparation and assessment of mortar-phase change materials (PCM) systems to gain a full understanding of using the heat stored in PCMs to delay or prevent ice formation in concrete. Desirable PCMs and light weight aggregates (LWA), which act as carriers of the PCMs, were first selected based on their thermal and physical properties. LWAs containing PCMs were prepared and assessed for different combinations of materials. Cyclic freeze-thaw mass loss, latent heat attenuation, and FTIR tests were conducted to characterize the stabilities of the LWA-PCMs. The thermal performances of the mortars containing LWA-PCMs were investigated using a longitudinal guarded comparative calorimeter (LGCC) that was operated under quasi-steady state conditions during the cooling/heating process. The results confirmed that PCMs can be steadily absorbed in LWAs without chemical reactions or great losses in latent heat when the LWA-PCMs were coated in a certain way. Cement paste was recommended to coat the surface of the LWA-PCMs for better compatibility with the system than that of traditional coating materials. The ability of the PCM to delay or prevent ice formation in mortar was verified from the exothermic/endothermic events associated with the phase transformations of the pore solution and PCM. In the present study, when up to 50% vol. of the LWA was replaced as carriers of PCM, the heat released by the PCM was sufficiently high to inhibit ice formation.

Background Glioblastoma (GBM) is the most common malignant brain tumor in adults. The prognosis of GBM patients is poor. Even with active standard treatment, the median overall survival is only 14.6 months. It is therefore critical to ascertain recurrence and search for factors that influence the prognosis of GBM. This study aimed to screen the variables related to the progression-free survival (PFS) and overall survival (OS) of GBM patients undergoing surgery and concurrent chemoradiotherapy, as well as propose a nomogram for individual risk prediction based on preoperative imaging parameters and clinicopathological variables readily available in clinical practice. Methods We retrospectively analyzed 114 consecutive patients with GBM who underwent surgery and concurrent chemoradiotherapy at the Second Affiliated Hospital, Zhejiang University School of Medicine from January 1st, 2015, to June 1st, 2018. Twenty-four preoperative magnetic resonance imaging (MRI) parameters were extracted manually from the Picture Archiving and Communication System (PACS). Clinicopathological factors were extracted from the electronic medical record system (EMRS). Least absolute shrinkage and selection operator (LASSO) regression and Cox regression were used for feature selection and model prediction, respectively. The models were presented using nomograms, which were applied to identify the risk of recurrence and survival according to the score. The performance of the nomograms to predict PFS and OS was tested with C-statistics, calibration plots, and Kaplan-Meier curves. Results The results revealed that sex, Karnofsky performance score (KPS), O6-methylglucamine-DNA methyltransferase (MGMT) protein expression, number of adjuvant chemotherapy cycles with temozolomide (TMZ), and the MRI signature effectively predicted PFS; and sex, KPS, extent of surgery, number of TMZ cycles, and MRI signature effectively predicted OS. The nomogram revealed good discriminative ability (C-statistics: 0.81 for PFS and 0.79 for OS). In the nomogram of PFS, patients with a score greater than 122 were considered to have a high risk of recurrence. In the nomogram of OS, the cutoff score were 115 and 145, and then patients were classified as low, medium, and high risk. Conclusions In conclusion, our nomograms can effectively predict the risk of recurrence and survival of GBM patients and thus can be a good guide for clinical practice.

The cervical spine injury is a complicated procedure in the combination of different injury loads and postures. The aim of this study is to investigate the injury mechanism considering different types of cervical curvatures subjected to contusion loads. A finite element model of a cervical spinal cord was constructed. Gray matter, white matter and pia matter were modeled and hyperelastic material properties were assigned. Convergence analysis and validation analysis were carried out. The model was simulated in 3 different spinal curvatures and loaded by 2 directions with 4 compression degrees. The maximum von Mises stress in the whole model was concentrated in the pia matter in all loading cases. When investigating spinal cord injury, the pia matter must be considered. For all three curvatures, the stress in the gray matter and white matter was higher in front-to-back loading condition than that in back-to-front loading condition. The front-to-back impact may cause a larger damage. A back-to-front load damaged the structure around the central canal and a front-to-back contusion load damaged the anterior horn of the spinal cord at most time. From the view of the maximum stress, the lordotic curvature did not show significant buffering effect. However, the pathological curvature had large areas affected and the lordotic curvature showed some benefits to some degree from the view of stress distribution.

PurposeTo evaluate the impact of resection margin on recurrence pattern and survival for hepatocellular carcinoma (HCC) with narrow margin resection, with the aim to guide postoperative treatment.Materials and MethodsTwo hundred forty HCC patients after curative hepatectomy between 2014 and 2016 were reviewed retrospectively. The cases were divided into narrow-margin (width of resection margin ResultsPostoperative recurrence was found in 128 (53.3%) patients. The recurrence rate was significantly higher in narrow-margin group than that in wide-margin group (P=0.001), especially for the pattern of marginal recurrence (20.8 vs. 4.5%, P=0.003). The 1-, 2-, 3-year RFS rates for the narrow-margin and wide-margin groups were 55.8, 43.9, 36.9, and 78.7, 67.9, 60.2%, respectively, with significant difference between the two groups (PConclusionPatients with narrow resection margin were associated with higher recurrence rate and worse survival than those with wide resection margin. These patients may benefit from adjuvant local treatment, such as radiotherapy.

This paper investigates damage and healing of cementitious materials based on fly ash (FA) with a special focus on the effect of repeated loading on the self-healing performance. In total, ...

In recent years, development of new structural systems based on fibre-reinforced polymer (FRP) materials attracted much attention. Concrete-filled FRP tubes taking advantages of both FRP and concrete show great promise for the potential application in piling, poles, highways overhead sign structures and bridge components. The hybrid member also provides an alternative solution for traditional transmission structures. However, the connection between concrete-filled FRP tubes and cross arms has not been fully investigated. This paper conducted an experimental study on steel cross arms inserted in concrete-filled circular glass FRP (GFRP) tubular columns. The structural responses of the system when the cross arms were subjected to concentrated loads were carefully recorded. It was found that the concrete-filled GFRP tubes could offer a sufficient restraint to the cross arm, leading to a limited deformation. Although stress and strain concentrated on the GFRP tube at the corner of the cross arm, no visible cracks were observed.

Corrosion and high temperature are two main detrimental factors that degenerate the mechanical properties and lead to decrease both in strength and durability of steel. The combined influence of corrosion and high temperature on the mechanical properties of grade D36 marine steel is proposed in this study. A series of tests were conducted to determine the post-fire mechanical properties of corroded marine steel. Specimens were corroded by a saltspray test, and then heated to 500 °C or 900 °C. Afterward, stress–strain curves, elastic modulus, yield stress and ultimate strength of the specimens were obtained from tensile coupon tests. Three-dimensional laser scanning was used to evaluate the impact of corrosion. The microstructure and fracture morphology analyses were carried out by metallographic microscope and scanning electron microscope (SEM), respectively. It was found that corrosion and high temperature have significant influence not only on the mechanical properties, but also on the microstructures and corresponding fracture morphology of grade D36 marine steel.

The complement factor I (CFI) gene polymorphisms have been reported to age-related macular degenerative (AMD) risk, nevertheless, above association is not consistent. We investigated a meta-analysis to evaluate the conclusions between CFI polymorphisms (rs10033900 and rs2285714) and AMD risk. An identification was covered with the PubMed and other databases through February 8, 2020. Odds ratios (OR) and 95% confidence intervals (CI) were used to assess the strength of associations. After a comprehensive search, 11 different articles (12 case–control studies for total AMD and 11 case–control studies about neovascular disease/geographic atrophy in AMD) were retrieved. Individuals carrying C-allele or CC genotype of rs10033900 polymorphism may have a decreased risk to be AMD disease. For example, there has a significantly decreased relationship between rs10033900 polymorphism and AMD both in the whole group, Caucasian population and population-based source of control. Moreover, a similar trend in subgroup of genotype method group by MALDI-TOF MS was detected. To classify the type of AMD in further, decreased association was also observed in both neovascular disease and geographic atrophy AMD. No association was found about rs2285714 polymorphism. Our present groundbreaking study suggests that the CFI rs10033900 polymorphism is potentially associated with the risk of AMD development.

External bonding with carbon fiber-reinforced polymer (CFRP) has been considered great potential in fatigue strengthening of defected steel components. Generally, it takes one to two weeks for a structural adhesive to achieve full strength in such a repair scheme. The potential risk of an environmental attack at the curing stage of adhesive has not been well understood. This paper presents an experimental study on the interfacial behavior of CFRP-steel double-lap joints subjected to salt fog spray or high relative humidity (RH) at the curing stage. Afterwards, the specimens were statically loaded to failure or applied by a pre-set number of fatigue cycles followed by a static test. CFRP laminate-patched specimens had the ability to resist six million high-stress range cycles while CFRP sheet-patched specimens only survived two million low-stress range cycles. After environmental exposure and fatigue loading, the bond strength loss ranged from 1% to 11%. Proper silane treatment was promising to maintain both the strength and stiffness of the bonded joints. Exposure to the harsh environment at the curing stage was detrimental to the mechanical properties of the structural adhesive Araldite 420. The unfavorable effects on the elastic modulus and ultimate strain were comparable to that of long-term exposure for well cured structural adhesive.

Purpose This study aims to determine the indications and effectiveness of transnasal endoscopic prelacrimal recess approach (PLRA) in patients with maxillary sinus inverted papilloma (IP). Methods We retrospectively analyzed 71 patients treated in our institution for maxillary sinus IP between August 2008 and April 2015. 20 patients underwent endoscopic surgery via PLRA. All the patients who had postoperative follow-up for 3 years were enrolled. Demographic data, surgical technique, location of IP attachment, intra- and postoperative complications, follow-up duration and recurrence were recorded. Results The outpatient follow-up period was 3–10 years after surgery. Recurrence of IP was seen in 6 (8.5%) of 71 patients, including 1 patient in the PLRA group. The recurrence rate was 5% in the PLRA group. Six of 71 patients experienced postoperative complications, but none was observed in the PLRA group. Conclusion Transnasal endoscopic PLRA is a minimally invasive, safe and effective method for maxillary sinus IP. The indication for PLRA is tumor pedicle located on the antero-inferior or infero-lateral wall or at multiple attachment sites of the maxillary sinus.

The purposes of this study were to investigate the activation and transport of atrazine in the presence of dissolved organic matter (DOM) and the surfactant (Triton X-100) and to understand interactions between DOM, Triton X-100, and atrazine. Uncontaminated soils collected from Nanjing, China, along with DOM extracted from rice straw and Triton X-100 (TX-100), were used in the study. The sorption and desorption experiments were carried out using the standard batch equilibration analysis. Soil column leaching was conducted with soil samples packed into PVC columns. Soil thin-layer chromatography was performed using soil and water mixture spread on a 0.5–0.7-mm-thick layer over 20 × 10-cm glass plates. Atrazine accumulation in maize was determined by planting maize in plastic pots (1 L) containing 1 kg soil mixed with 1.0 mg kg−1 atrazine. Soils were watered with different solutions, with the relative water content of 60%. Using batch experiment and soil thin-layer chromatography, application of DOM and surfactant reduced sorption and increased desorption of atrazine in soil. In column experiment, DOM and surfactant significantly promoted the mobility of atrazine in soil and the total concentration of atrazine in leachate of the soil column. Accumulation of atrazine in both maize roots and shoots increased with the elevated concentration of surfactant, whereas the content of atrazine declined with the increase of the DOM concentration. Dissolved organic matter and TX-100 affected the partitioning and transport of atrazine in soil–water and soil–plant ecosystems.

In recent years, carbon fiber-reinforced polymer (CFRP) externally bonded to steel members has been considered an effective technique for fatigue crack repair of steel components. This paper investigated the fatigue behavior of six cracked steel beams strengthened using CFRP laminates via two approaches, i.e., sole adhesive bonding and adhesive bonding together with mechanical anchorage. Two types of epoxies were selected to compare the effectiveness. The tensile flange of the steel beam was artificially cut to simulate an initial crack. A digital image correlation (DIC) system was adopted to detect strain distribution along the retrofitting patches. Different failure modes were observed for specimens with different retrofitting schemes. Test results showed that, in comparison with control specimens with sole adhesive bonding, application of mechanical anchorage significantly retarded crack propagation and extended fatigue life of the steel beams attributed to the pronounced frictional bond. The crack mouth opening displacement (CMOD) was also considerably reduced. The displacement fields obtained from the DIC recorded at specific crack lengths were analyzed to provide information on strain distribution along the CFRP laminates and corresponding bond-slip relationship. This study extends the understanding of fatigue repair for steel beams and provides useful suggestions for the strengthening method. © 2018 Elsevier Ltd

This paper presents a numerical study on the stress intensity factor (SIF) and fatigue behavior of carbon fiber-reinforced polymer (CFRP) strengthened steel plates with center inclined cracks under uniaxial tensile fatigue loading. Effects of prestress level in CFRP and initial crack inclination angle were investigated. Results indicated that the CFRP laminates could reduce the mode I SIF and effective SIF range, thereby enhancing the fatigue life of the steel plates. The strengthening was more efficient by using the prestressing technique. It was found that fatigue life was approximate for specimens with an identical crack projection length on the plane perpendicular to the load. This indicated that the effect of the initial crack inclination angle on the fatigue crack propagation life of the steel plate was limited when subjected to a unidirectional load. The findings of this study can be adopted as a reference for the repair of existing metallic structures with inclined cracks.

The interfacial bond-slip relationship between fiber-reinforced polymer (FRP) and steel plays an important role in analyzing FRP retrofitted steel structures. Different failure modes and epoxy types (i.e., linear epoxy and nonlinear epoxy) lead to various bond-slip relationships. Although several models have been proposed to predict the bond-slip behavior, different models were developed for different emphasis, which may result in inconvenience when being used. This paper proposed a unified bond-slip model by considering different failure modes and epoxy types. A database of bond strength comprising of 400 FRP-to-steel single-/double-lap shear joints was collected. By analytical reasoning, key factors that influence the bond parameters were identified and configurations of the model were derived. The unknown coefficients in the model were determined subsequently by nonlinear regression analysis using the derived closed-form analytical solutions. Different coefficients were proposed in terms of different failure modes and epoxy types. Furthermore, if the failure modes are unknown before experimental investigation, the proposed model is also capable of giving reasonable predictions. Comparison between theoretical results and test data from the literature was performed to validate the modeling work. Afterward, a parametric study was conducted to further investigate effects of the key parameters on the interfacial behavior.

This work presents a full reliability-based analysis framework for fiber-reinforced polymer (FRP)-to-concrete bonded joints considering model uncertainty. Eight frequently used bond strength models for FRP-to-concrete bonded joints were calibrated by defining a model factor. A total of 641 well-documented tests were considered. Four of the eight models had model factors that correlated with input design parameters and the systematic part of the model factor was removed by a regression equation f . By doing this type of characterization, all eight model factors could be comparatively uniform and described by lognormally distributed random variables . The merit of the uniform model uncertainties after calibration for the eight models was established by the reliability analysis. This study improves the predictability of concrete strengthened with fiber composites and provides useful suggestions on their model uncertainties in engineering practice.

This study investigated the stress recovery behavior of an Fe-Mn-Si-Cr-Ni-VC shape memory alloy for prestressed strengthening, focusing on high-temperature activation of the alloy. The effects of different prestrain levels (1%, 2%, 4%, 6% and 8%), activation temperatures (100, 150, 200, 250, 300, 350, and 455 °C), and initial preloads (50, 100 and 150 MPa) on recovery stress were evaluated to propose an optimum activation strategy. In addition, mechanical properties of the Fe-SMA after activation, including the performance under a second high-temperature activation (up to 455 °C) and high-cycle fatigue (HCF) loadings (stress-controlled with a stress range of 57 MPa), were studied. According to the results, a prestrain level of 2% was found to be the optimum level when the activation temperature was below 200 °C. However, at higher activation temperatures, an increased prestrain resulted in an increase in the recovery stress. In this study, the specimens prestrained by 4 and 8% and activated by 350 °C led to a recovery stress of 421 and 445 MPa, respectively. According to the fatigue test results, the recovery stress decreased by 12 – 15% after two million load cycles, regardless of the activation temperature.

Steel structures under dynamic loading are prone to fatigue damage and a considerable number of metallic infrastructure in the world are structurally deficient. The fatigue behavior of defected steel beams mechanically retrofitted by different high-strength materials was experimentally studied in this work. The steel beam was I section with an artificial cut at the mid-span and tested under fatigue loading. The specimens were strengthened on the tension flange by carbon fiber reinforced polymer (CFRP) laminate, high strength steel (HSS) plate or SafStrip (SAF) plate. Three mechanical anchorage schemes were designed to test their efficiencies. The fatigue crack propagation was recorded to explore the crack growth rate. Strain gauges were installed on the strengthening material to monitor the strain development. The stress intensity factor (SIF) at the crack front was calculated based on analytical solution and numerical simulation; then, the results were compared with experimental findings. It was demonstrated that the strengthening significantly increased the fatigue life of the beams. The attached strengthening materials not only globally shared a portion of the far-field load on the cracked steel section but also provided a local constraining effect, both of which reduced the crack mouth opening displacement (CMOD) and SIF. The different CMODs resulted from the different retrofitting configurations indicated significant variation in the crack constraining effect caused by various retrofitting systems, which cannot be neglected in analytical modeling.

In recent years, externally bonded carbon fibre–reinforced polymer has been considered an innovative way to strengthen steel structures attributed to its high strength-to-weight ratio, excellent corrosion resistance and fatigue performance. This article presents an experimental and numerical study on the fatigue behaviour of defected steel beams strengthened with carbon fibre–reinforced polymer laminates, with a special focus on the effect of interfacial debonding. Analytical modelling and numerical simulation confirmed that the interfacial debonding had a pronounced effect on carbon fibre–reinforced polymer strain and stress intensity factor at the crack front. After introducing interfacial debonding from experimental findings into the numerical analysis, the fatigue life and crack propagation versus cycle numbers of the specimens compared well with the test results. Based on the current experimental program, specimens with Sikadur 30 were more prone to debonding failure; therefore, Araldite 420 is suggested for strengthening schemes.

Fiber-reinforced polymer (FRP) materials nowadays have attracted much attention in both retrofitting of aged infrastructure and developing of new structural systems attributed to the outstanding mechanical properties. Extensive studies have been performed on concrete-filled glass FRP (GFRP) tubes for the potential application in piling, poles, highways overhead sign structures and bridge components. The new hybrid member also provides an alternative solution for traditional transmission structures. However, the connection between concrete-filled GFRP tubes and cross arms has not been fully understood. In this paper, an experimental study and theoretical analysis were conducted on the behavior of cross arms inserted in concrete-filled circular GFRP tubular columns. Steel bars with a larger stiffness in comparison with GFRP tubes were selected here for the cross arm to simulate a more severe scenario. The structural responses of the system when the cross arms were subjected to concentrated loads were carefully recorded. Experimental results showed that the concrete-filled GFRP tubes could offer a sufficient restraint to the deformation of the cross arm. No visible cracks were found on the GFRP tube at the corner of the cross arm where the stress and strain concentrated. Theoretical solutions based on available theories and equations were adopted to predict the displacement of the cross arms and a good agreement was achieved between the prediction results and experimental findings.

This paper presents a numerical study on the fatigue behaviour of edge cracked steel plates strengthened with carbon fibre reinforced polymer (CFRP) laminates based on the boundary element method. The models were first validated by a comparison with experimental data in the literature, followed by a further investigation into the effects of initial damage degree, bond configuration and crack type on the fatigue behaviour of retrofitted specimens. Results indicated that CFRP overlays could effectively slow down crack growth and extend fatigue life of edge cracked steel plates, regardless of the initial damage levels. It seems better to adopt an early repair considering the total fatigue life. Double-sided repair showed significant superiority over single-sided repair when equivalent composite materials were used. For the repair configuration presented herein, the strengthening was more efficient for edge cracked steel plates than centre cracked steel plates.

Corrosion is a major cause of durability deterioration for reinforced concrete (RC) structures. This paper investigated the random evolution process of corrosion in steel bars under a constant corrosion current density. A probabilistic prediction model was developed combining a continuous-time Markov chain model with the Faraday law. The model parameter, state interval, which represents the difference between the actual adjacent corrosion depths, was calibrated by test data and statistically studied. Markov model predicted results showed that the corrosion depth followed the Poisson distribution while the longitudinal nonuniformity factor of corroded steel bars R, which was defined as the ratio of the average cross-sectional area to the minimum one, followed the Gumbel distribution. The probability distribution parameters of the factor R were determined by Monte-Carlo simulation. The corrosion depth and the factor R predicted by the Markov model agreed well with the experimental data.