Search

Background To compare the traditional single-layer and double-layer suture renorrhaphy with modified “Binding” suture renorrhaphy (whole rim of the wound was closed by the all-layer flow suture starting from the parenchyma cut edges to hilum, followed by the final defect closure) in robotic partial nephrectomy (RPN) for treating localized renal cell carcinoma in our large institutional experience. Methods We retrospectively reviewed clinical data of 406 consecutive patients who underwent RPN from May 2018 and December 2020 in our center. The demographic and oncologic outcome variables were compared between different renal reconstruction groups and the effect of these suture techniques on renal function outcomes was also evaluated. Results For the single-layer group, median operative time and warm ischemic time were significantly less than that of the double-layer and “Binding” groups (p p = 0.014) was also detected within postoperative 3 months from baseline, but this difference lost its statistical significance from 3th month to the last follow-up. The changes in postoperative creatinine values were clinically insignificant among the three groups. In a sub-analysis over 258 patients with moderate/high nephrometry score, those patients who underwent “Binding” suture had an undifferentiated warm ischemic time, estimated blood loss, and length of hospitalization stay with a decreased risk of Grade III complications (postoperative hemorrhage requiring intervention) and improved renal function recovery during the whole follow-up. Conclusion Single-layer suture renorrhaphy may be associated with better renal functional preservation and could prove to be reliable in patients with low-complexity tumor (RENAL score ≤ 6). Patients with moderate/high-complexity tumor (RENAL score ≥ 7) might represent a subgroup of patients having a functional benefit after “Binding” suture renorrhaphy even in the long-term period. Graphical abstract

For load-carrying fillet welded joints, the fracture due to the crack propagation near the root takes place frequently in practical engineering. Given the essential role of welded joints in Tee configurations with double-sided and single-sided welds, the assessments of the fracture behavior of such joints and the stress intensity factors (SIFs) related to the crack opening (mode-I) fracture and the sliding or shear (mode-II) fracture are the main topic of this study. A planar structure finite element model incorporating the crack body with the singularity in front of the crack tip is developed to simulate the failure at weld root due to the presence of non-penetrating regions. Effects of the fillet angle (θf), the effective weld throat thickness (he), the thicknesses of the main plate (tp) and the cross plate (tc) on SIFs are analyzed. The results show that the effect of he/tp has a significant effect on SIFs and becomes more obvious as the crack is propagated at the weld root and inside the fillet weld. The increase of θf significantly amplifies the SIFs especially for the fracture mode related to KII. The effect of tc/tp is insignificant for the fracture mode related to KI while its amplification results in a moderate increase of KII especially for the single-sided fillet welds.

The significant role of traffic emissions mixed from various sources in urban air pollution has been widely recognized. However, the corresponding contributions to the roadside particle distribution are poorly understood due to the mixed impacts of various sources. Particle number concentrations of different sizes at the roadside in Nankai District of Tianjin were continuously monitored using a portable aerosol particle spectrometer during the morning rush hour (07:30-09:20) from Nov. 9, 2018 to Jan. 6, 2019. Characteristic and influencing factors of particle size distributions were discussed combined with temperature and relative humidity data, while potential sources of particles at the roadside were identified based on size distribution analysis. The results showed that the average total particle number concentrations were 502 cm

A low MgO content in sinter is conducive to reduce the MgO content in blast furnace slag. This study investigated the effect of MgO content in sinter on the softening—melting behavior of the mixed burden based on fluxed pellets. When the MgO content increased from 1.31wt% to 1.55wt%, the melting temperature of sinter increased to 1521°C. Such an increase was due to the formation of the high-melting-point slag phase. The reduction degradation index of sinter with 1.31wt% MgO content was better than that of others. The initial softening temperature of the mixed burden increased from 1104 to 1126°C as MgO content in sinter increased from 1.31wt% to 1.55wt%, and the melting temperature decreased from 1494 to 1460°C. The permeability index (S-value) of mixed burden decreased to 594.46 kPa·°C under a high MgO content with 1.55wt%, indicating that the permeability was improved. The slag phase composition of burden was mainly akermarite (Ca2MgSiO7) when the MgO content in sinter was 1.55wt%. The melting point of akermarite is 1450°C, which is lower than other phases.

Trapezoidal corrugated steel webs under panting fatigue are represented by repeated cyclical out-of-plane deflections of their subpanel with mixed-mode cracks. Compared to stiffened flat webs, notable fatigue crack formation could take place along with local deflection. Fatigue tests were conducted for nine composite girders with slender webs and varied corrugation dimensions. Nearly all test girders showed notable local and interactive shear buckling at the corrugated web panel and the panting fatigue cracks are formed under repeated cyclical deflection while the compression and tension flanges remain intact. Fatigue cracks are initiated at the junction between the vertical (longer) edge of the subpanel and the boundary of the out-of-plane deflection region. The crack propagation paths appear to deviate from the original vertical edge due to buckling induced out-of-plane deflection under mixed-mode stress condition. The test results demonstrate that the Category B’ and Category E suggested by the AASHTO LRFD bridge fatigue design provisions related to the principal stress range and the nominal membrane shear stress range respectively can be considered for the prediction of the fatigue life of trapezoidal Corrugated steel webs in test girders. An appropriate allowance of both the shear stress along the vertical web edge and tension stress from the diagonal plastified tension band is given for the mixed-mode stress intensity factor. The proposed fatigue life prediction allowing for mixed-mode crack growth mostly compares well with test results and its further improvement for the case with higher web panel slenderness ratio is discussed.

Over the years, it has become obvious that simultaneous backfill grouting is of great significance to the design of the tunnel lining and process control of shield construction. It is essential to ...

This paper outlines an experimental study on the static and dynamic compressive creep behaviour of structural silicone adhesively bonded joints. The silicone adhesives are subjected to dyna...

Objective: This study aims to observe the apoptosis of optic nerve cells after retinal contusion in rabbits, and explore the mechanism of its occurrence. Methods: Forty-eight healthy adult chinchilla rabbits without eye diseases were randomly divided into eight groups: post-contusion hour 1, hour 3, day 1, day 3, day 7, day 14 and day 28, and normal control groups (n = 6, each group). The right eye was the injured eye, which was induced by the modified Allen's falling strike method. The rabbit eye specimens were obtained on time after the models were established. Five-mm pathological sections of the post-laminar optic nerve were prepared, tissue morphology was observed, and glial cells were counted. The apoptosis of optic nerve cells was observed by electron microscopy and TUNEL staining. Results and Discussion: Optic nerve fibers were disarranged and glial cells were out of order at hour 1, hour 3, day 1, day 3 and day 7 after injury. Furthermore, the cell counts were reduced at hour 1, hour 3, day 1, day 3, day 7, day 14 and day 28 after injury; and the differences were statistically significant, compared with the normal control group (P < 0.01). Results suggest that the apoptosis of optic nerve glial cells may also be one of the reasons for poor recovery of visual function after retinal contusion.

Precise and reliable long-term streamflow prediction contributes to water resources planning and management. Artificial neural network (ANN) have shown its remarkable ability in forecasting non-linear hydrological processes without involvement of complex, dynamic, hydrological and hydro-climatologic physical process in the water shed. To improve its non-stationary responses, decomposition methods are adopted as pre-processing methods in this study including Empirical Mode Decomposition (EMD), Ensemble Empirical Mode Decomposition (EEMD) and Seasonal-Trend decomposition using Loess (STL). The original time sequence is decomposed to several components, which are then taken as the inputs of the ANN model. EMD and EEMD are data- adaptable methods, and thus the number of Intrinsic Mode Functions (IMFs) might differ for different sequences, leading to the discrepancy of the input number for ANN model in training and predicting. Fisher’s ordered clustering is thus used to classify the IMFs into a determined number of classes based on their frequency spectrum resulting from Maximum Entropy Spectral Analysis (MESA). The proposed methodology is applied on four important hydrological stations on the upper stream of the Yellow River and the Yangtze River in China, respectively, to forecast the streamflow of the next whole year with the historical daily data of the past 6 years. The Nash-Sutcliffe efficiencies of the monthly prediction are higher than 0.85 for all of the four cases, and various indicators indicates that the proposed hybrid method of STL-ANN performs better than other compared methods. The highlights of this study lies in that only historical daily streamflow data is used to derive an accurate long-term prediction by data mining based on decomposition technology and mapping relationships between the decomposed components and the original sequence in the future.

This paper presents a study on the fatigue behaviour of slender corrugated webs subjected to plate breathing. It outlines a fatigue test of nine test girders with buckling in interactive buckling manner of the corrugated webs. Characteristic fatigue crack propagation manners and fatigue endurances of the corrugated webs are analyzed. Finite element models considering crack propagation details and out-of-plane deflection have been developed to investigate the stress intensity factor under shear and its combined modes. Proposed theoretical prediction allowing for the interacted shear and tearing fracture modes is confirmed with good degree of accuracy and its further improvement is also discussed.

Artificial neural network (ANN) combined with signal decomposing methods is effective for long‐term streamflow time series forecasting. ANN is a kind of machine learning method utilized widely for streamflow time series, and which performs well in forecasting nonstationary time series without the need of physical analysis for complex and dynamic hydrological processes. Most studies take multiple factors determining the streamflow as inputs such as rainfall. In this study, a long‐term streamflow forecasting model depending only on the historical streamflow data is proposed. Various preprocessing techniques, including empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD) and discrete wavelet transform (DWT), are first used to decompose the streamflow time series into simple components with different timescale characteristics, and the relation between these components and the original streamflow at the next time step is analyzed by ANN. Hybrid models EMD‐ANN, EEMD‐ANN and DWT‐ANN are developed in this study for long‐term daily streamflow forecasting, and performance measures root mean square error (RMSE), mean absolute percentage error (MAPE) and Nash–Sutcliffe efficiency (NSE) indicate that the proposed EEMD‐ANN method performs better than EMD‐ANN and DWT‐ANN models, especially in high flow forecasting.

In this paper the characteristics of CFRP reinforcement on the improvement of the fatigue strength of aluminium alloy plates with fastener holes are investigated. The CFRP reinforcement schemes including the number of laminate layers, single-sided and double-sided strengthening are taken into account. Fatigue tests with constant loading amplitude were conducted to compare different failure mechanisms involved with such structural details. The stiffness degradation of test specimen failed by interfacial debonding is shown to be relatively gradual prior to plate rupture while the propagation of the fatigue crack at the transition of the punching surface appears to be retarded to some extent due to the tensile strengthening of the carbon fibre. The contributions of carbon fibre and adhesive interface to the strength improvement are quantified. Discussions are also made for the fatigue life of similar details with some other hole forming methods reported in the literature. Recommendations are given for the assessment of the fatigue life of CFRP reinforced specimens studied herein with appropriate detail classes codified in the BS8118 standard. Finally, a new formula allowing for the contributions of the plate and carbon fibre in tension, the adhesive interface in shear and additional secondary bending effect is proposed in the evaluation of the improvement fatigue endurance. The proposed formula is verified from a good correlation with finite element analytical results and from original test data with a notable reduction of scatters. Its application scope is also discussed.

Background Although constitutive activating mutations in the Wnt/β-catenin signalling pathway are important for colorectal cancer development, canonical signalling through Wnt ligands is essential for β-catenin activation. Here, we investigated the role of (pro)renin receptor ((P)RR), a component of the Wnt receptor complex, in the pathogenesis of colorectal cancer. Methods (P)RR silencing was performed in human colorectal cancer cells containing constitutive activating mutations in the Wnt/β-catenin pathway. (P)RR overexpression was induced in normal colon epithelial cells. Protein and mRNA levels of pathway components were detected, and Wnt signalling activity was measured using a β-catenin reporter. Cell proliferative activity and apoptosis were evaluated using WST-1 assay and flow cytometry. Xenografts were induced in nude mice. Results (P)RR expression was greater in colorectal cancer tissues and cells than in normal colorectal samples. Patients with strong (P)RR expression took more proportion in groups with poorly-differentiated, advanced and rapidly-progressing cancers. (P)RR silencing attenuated the pathway in colorectal cancer cells, impaired their proliferation in vitro and vivo. (P)RR overexpression enhanced the pathway and proliferation of normal colon epithelial cells. Conclusions Aberrant (P)RR expression promotes colorectal cancer through the Wnt/β-catenin signalling pathway despite constitutive pathway-activating mutations. (P)RR is a potential diagnostic and therapeutic target for colorectal cancer.

The present paper deals with the shear buckling response of trapezoidal profiled webs in girders with concrete-filled rectangular hollow section (RHS) flanges. It outlines an experimental work of four girders with shear buckled trapezoidal profiled webs in interactive and global manners. Characteristic strain distributions on the trapezoidal profiled webs are reported. The analysis of load-deformation responses indicates that the trapezoidal profiled web buckled in the global manner suffered greater strength drops at early stage and less strength improvement contributed by the concrete-filled RHS flange in contrast to those buckled in interactive manner with partial local buckling. Finite element models explicitly allowing for isolated trapezoidal profiled webs with varied side boundaries and visual girder models with proposed design ratios are then presented for 572 cases. It is shown that the first eigenmode shape and critical stressing of the trapezoidal profiled webs are most likely influenced when the shear buckling in local manner takes place. Related geometric ratios involved with shear span, web slenderness, trapezoid altitude and subpanel height are examined through a parametric study. Afterwards, an analytical formula incorporating a proposed rigidity ratio as well as a correlated contribution coefficient is proposed for the determining shear buckling strength of trapezoidal profiled webs in the girders with concrete-filled RHS flanges. The proposed formula is verified in contrast to referred ones through a comparative study which can be deemed suitable for the design of trapezoidal profiled webs in girders with concrete-filled rectangular hollow section (RHS) flanges.

The aim of this study is to find out the degradation of dynamic behaviour of bridge girders with trapezoidal profiled webs when subjected to different vehicle moving loads. Finite element modelling based parametric analysis is demonstrated to be desirable in capturing the dynamic deflection and stress state of critical structural details of girders. The model is validated in the modal analysis through a comparison with theoretical eigenfrequencies. The vibration characteristics are shown to be significantly affected by the corrugation details. The structural service life results of analysed bridge girders are in close agreement with experimental data. It is shown that the dynamic nodal velocity and deflection of analysed bridge girders are greatly affected by the magnitude of the load corresponding to the overload of the vehicle in contrast to the vehicle travel speed. Similar observations can be made for the fatigue life prediction analysis related to the crack initiation when unfavourable effects of the overload vehicle are concerned. Presented analytical results using a fracture mechanics approach could be taken as a good basis for the service life assessment of related bridges with the desired level of performance or functionality.

Human esophageal cancer (hESC) cell motility adopts various modes, resulting in hESC progression and poor survival. However, how tripartite motif 59 (TRIM59), as the ubiquitination machinery, participates in hESC metastasis is not completely understood. The results indicated that TRIM59 was aberrantly upregulated in hESC tissues compared with adjacent healthy esophageal tissues, which was associated with poor survival and advanced TNM state among patients with hESC. Moreover, patients with hESC with higher TRIM59 expression displayed undetectable p53 expression, which contributed to enhanced progression and motility of hESC. At the molecular level, TRIM59 was indicated to be an E3 putative ubiquitin ligase that targeted the p53 protein, leading to increased degradation of p53, which resulted in decreased chemosensitivity to cisplatin. TRIM59 knockdown reduced TRIM59 expression, increased p53 protein expression, and decreased hESC cell viability, clone formation and migration compared with the small interfering RNA negative control (siNC) group. Furthermore, hESC cell lines were more sensitive to cisplatin in the TRIM59-knockdown group compared with the siNC group. The results indicated a relationship between TRIM59, p53 and the chemosensitivity of cisplatin. The present study suggested that TRIM59 may serve as a promising prognostic indicator for patients with hESC.

This paper presents an analytical assessment of surface crack growth behaviour of composite girders with concrete filled tubular flanges and corrugated webs (CGCTFCWs) with the aid of substructure-based numerical modelling. Distinctive features of crack propagation on the tubular flanges with considerable stress gradient from lower to upper cracked tube surface interacted with the weld toes along the corrugated webs are replicated in the substructure modelling and discussed in details. Based on a favourable verification of stress intensity factors (SIFs) with reported model with semi-elliptical surface crack in plates and rectangular hollow section tube, an analytically derived substructure model of critical corrugated web-flange welded details coupled to the rest of the structure is developed. Such a model is distinguished itself from that based on original Newman and Raju equation by an amendatory of the stress gradient induced by the shifting of the neutral axis and the geometry as crack penetrated through the tube wall. Based on a parametric analysis, the SIFs significantly influenced by the corrugation depth ratio, the tube thickness-to-width ratio and the tube thickness-to-depth ratio in relation with the dimensionless crack length are demonstrated and taken into account in the derivation of a new geometry amendatory coefficient. An experimental investigation was also implemented to further examine and validate the modelling crack propagation response. The resultant fatigue fracture manner and the stress concentration of the hot spot are virtually in good correlation with the modelling results. Moreover, the relations between the crack growth increment and fatigue endurances from experimental measurement match well with these predicted by the NASGRO equation using amended SIFs, indicating that the proposed model is able to trace the distinct geometry effects of the corrugated web and the tubular flange on the crack propagation response of CGCTFCWs.

This paper presents an experimental study on the fatigue life estimation of off-centrally cracked aluminum plates. Typical theoretical equations for off-central, central and edge cracks were reviewed and compared in terms of their sensitive parameters and applicability. A finite element model has been validated in its capacity in modelling the influences of eccentricity and crack size on the boundary correction coefficients. The Forman equation has been employed along with numerical results for the prediction of fatigue lives. Based on the test data, the fatigue life results of aluminum plates with and without patched laminate repair have been compared with codified fatigue classes. It is demonstrated that the repair at the crack tip close to the plate edge is effective in the fatigue life improvement for off-centrally crackedaluminum plates.

Background The (pro) renin receptor ((P)RR) plays important roles in various pathways, such as the Wnt/β-catenin, renin-angiotensin system (RAS), MAPK/ERK and PI3K/AKT/mTOR pathways, that are involved in a wide range of physiological and pathological processes incorporating the tumorigenesis. However, our knowledge about (P) RR was mostly limited to its roles in cardiovascular and renal physiological functions and diseases. In the past 5 years, however, compelling evidence has revealed that (P) RR is aberrantly expressed in and contributes to the development of various cancers by different means. For instance, (P) RR was recently demonstrated to induce the oncogenesis of pancreatic, colorectal and brain cancers via the Wnt signaling, while promote the endometrial cancer and glioblastoma through the RAS. Methods Combining with the deep analysis of big data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, this review updates and summarizes the recent studies about the newly recognized roles of (P) RR in the pathophysiological processes of cancer development and its detailed functions through related pathways, as well as the novel research progress of (P) RR in related fields including the development and application of soluble (P) RR detection kit and monoclonal (P) RR antibody. Results This review provides an overview of the essential roles of (P) RR in the tumorigenesis and progression of various cancers and offers a translational outlook for the future research and clinical practices. Conclusion (P) RR in the tumor tissues and/or body fluids of patients may be a novel and promising biomarker and potential therapeutic target for diagnosis, treatment and prognosis prediction in various cancers. Graphical abstract

Background Recent studies have focused on initial clinical and epidemiological characteristics of the coronavirus disease 2019 (COVID-19), which is the mainly revealing situation in Wuhan, Hubei. Aim This study aims to reveal more data on the epidemiological and clinical characteristics of COVID-19 patients outside of Wuhan, Zhejiang, China. Design This study was a retrospective case series. Methods Eighty-eight cases of laboratory-confirmed and three cases of clinically confirmed COVID-19 were admitted to five hospitals in Zhejiang province, China. Data were collected from 20 January 2020 to 11 February 2020. Results and discussion Of all 91 patients, 88 (96.70%) were laboratory-confirmed COVID-19 with throat swab samples that tested positive for SARS-Cov-2, three (3.30%) cases were clinically diagnosed. The median age of the patients was 50 (36.5–57) years, and female accounted for 59.34%. In this sample, 40 (43.96%) patients had contracted the disease from local cases, 31 (34.07%) patients had been to Wuhan/Hubei, eight (8.79%) patients had contacted with people from Wuhan, and 11 (12.09%) patients were diagnosed after having flown together in the same flight with no passenger that could later be identified as the source of infection. In particular within the city of Ningbo, 60.52% cases can be traced back to an event held in a temple. The most common symptoms were fever (71.43%), cough (60.44%) and fatigue (43.96%). The median of incubation period was 6 (interquartile range 3–8) days and the median time from the first visit to a doctor to the confirmed diagnosis was 1 (1–2) days. According to the chest computed tomography scans, 67.03% cases had bilateral pneumonia. Conclusions Social activity cluster, family cluster and flying alongside with persons already infected with COVID-19 were how people got infected with COVID-19 in Zhejiang.

This study was aimed at exploring the expression of lncRNA TUG1 in non-small cell lung cancer (NSCLC) and analyzing the correlations between TUG1 expression and an NSCLC patient's clinical and pathological parameters and prognosis.This study included 132 NSCLC patients who were admitted between January 2012 and May 2013 in our hospital. Expression levels of TUG1 expression in the resected cancer tissue and normal adjacent tissue (NAT) were assessed using the ISH and RT-qPCR assays to analyze the correlations between TUG1 expression in NSCLC tissue and an NSCLC patient's clinical and pathological parameters and prognosis.Compared to NAT, NSCLC tissue has a lower expression level of TUG1. The TUG1 expression further decreases as NSCLC progressed to a later stage, indicating a statistically significant difference (p0.01 or p0.001). High TUG1 expression is not strongly associated with age, gender, smoking history, or the degree of differentiation of NSCLC (p0.05) but exhibits close correlations with tumor size, TNM stage, and lymph node metastasis (p0.05). Patients with a higher level of TUG1 expression have a higher survival rate and a longer survival time than those with lower TUG1 expression. The inter-group differences were statistically significant (p0.05).Considering TUG1 presence in the development and progression of NSCLC, hopefully, it can be used as a tumor marker in the diagnostic workup of patients with NSCLC.

The performance of the primary slag in the cohesive zone of blast furnace is critical for smooth operation of blast furnace ironmaking process. In the present work, the CaO–SiO2–MgO–TiO2–Al2O3–FeO slag system was studied to identify the influence of the FeO and the TiO2 on the melting features and viscosity. The temperatures of melting features are found to decrease with increasing FeO from 5 wt% to 20 wt% and increase with increasing TiO2 from 5 wt% to 15 wt%. The viscosities of the slag change with TiO2 can be divided into four periods, which are slow period, rapid period, slow down period and dramatically rise period. The introduction of TiO2 into silicate network performs as network modifier at high temperature and network former at a relative low temperature. FeO can decrease the effect of Ti2O6 4– chain units and decrease the precipitation temperature of the solid phase.

Steel-glass composite beams with the combination of glass webs and steel flanges are known to be able to attain good ductility in contrast to pure glass panels. As a concentrated load is introduced away from the middle of the beam span, its resultant stress concentration can induce shear compression failure on the glass web which is distinguished itself from flexure failure as reported in the literature. This paper presents an experimental study on the in-plane shear compression behaviour of composite beams with laminated glass webs. Distinct failure mode related to load induced edge delamination traces on the glass web is reported. Based on the test results, the distribution of acting strains and stresses within the composite beams is plotted. The formation of inclined cracks on the glass web is justified as the stress trajectories are prone to bend to form a diagonal tension stress state. It is shown from the response of composite beams that the strength and elastic stiffness of composite beams are improved when the adhesives with better mechanical properties are used. Afterwards, it is shown that the strengths of test specimens are greater than these of counterpart glass stabilizing fins or stiffening fins due to the flexibility of adhesive joining. Finally, the test strengths have been evaluated based on the edge delamination traces and the equilibrium of the energy dissipation of proposed mechanism. It is demonstrated that the proposed mechanism in contrast to referred formulae is able to give a better prediction of strength.

This study explored the Self-selection issues present in the individual bonus ratio and individual performance of housing brokerage employees. The participants in the survey were housing brokerage employees in Kaohsiung City, Taiwan. In this study, individual performance and individual bonus ratio were designated as interacting endogenous variables. Evaluations were conducted using two-phase simultaneous equations. The empirical results showed the following: 1. a higher bonus ratio resulted in better individual performance, while better individual performance resulted in a higher bonus ratio. 2. Male workers performed significantly poorer than female workers. 3. Junior college education, hours of work, and low salary had a significant positive effect on individual performance. 4. Significantly more men than women selected brokerage work with a high individual bonus ratio. 5. Employees with university or higher education, low salary, and working in the direct selling system had significantly lower individual bonus ratios.

This paper presents an experimental and finite element analysis based mathematical modelling of cyclic behaviour of the component of hollow structural section (HSS) columns under bolt tensile loads. This component acts as an important constituent part to the blind bolted connections with HSS columns. Two typical failure modes and their related hysteretic curves are examined experimentally. It is shown that force versus displacement curves under monotonic loading can be regarded as the upper bound of the envelope of the counterpart cyclic response. Moreover, the hysteretic force–displacement curves of test columns with relatively thick tube walls demonstrate significant pinching manner thus less energy dissipative capacity. Based on the calibrated finite element model, the flexibility of tube wall and its influences on the connection response are compared for two failure modes. Parametric analyses are also performed to investigate the influence of geometric parameters on the elastic stiffness and yield strength. The mathematical hysteretic models allowing for the behaviour of the connections in two typical failure modes are proposed that distinguishes the developed model from those reported in the literature. It is demonstrated that the proposed model incorporating degradations of stiffness and/or energy dissipation can achieve a good representation of test hysteretic behaviours.

Open-hole details have gained widely application in bolted connections subjected to fatigue loading. Although the use of carbon fibre reinforced polymer (CFRP) can be efficient in strengthening critically stressed tension area, its benefit in improving the fatigue life of open-hole details has not been extensively evaluated. This paper presents the results of an experimental and finite element analytical study on the fatigue behaviour of CFRP strengthened open-hole steel plates. The merits resulted from CFRP strengthening are investigated and compared with some others from referred open-hole fabrication methods and these with artificial initial cracks or notches as reported in the literature. Typical failure modes, local strain evolution and stiffness degradation behaviour of the test open-hole details are reported. The fatigue life results are evaluated and compared against the design curves of the AASHTO. The results show that the use of single and triple layered CFRP strengthening results in fatigue life enhancement of nearly 20% and 60% respectively in contrast to bare steel open-hole plates. Incorporating the stress ratios allowing for fibrous rupture and steel-adhesive interface failure, the fatigue life of CFRP strengthened specimens can be properly evaluated. Finally, the geometric and configuration parameters of CFRP on the stress concentration of the open-hole details are studied based on finite element modelling. It is demonstrated that the studied stress concentration can be reduced with the increase of the modulus of carbon fibre and the number of CFRP layers. The contribution of the effective width of CFRP to the decrease of stress concentration is also discussed.