A review on the mechanical properties of aged wood and salvaged timber

The effect of time on the mechanical properties of wood is of interest for structural engineers, wood technologists and conservators; for the old timber structure assessment, for the potential reuse of salvaged timbers and poles and for the conservation of wooden artefacts as well. The topic was investigated since the 50’s, but the results reported in literature are not always concordant. This is a consequence of the fact that this kind of research works are quite difficult, as a consequence of the material characteristics itself: mechanical properties variability, low availability of material, uncertainty about the “history” of the tested material, unknown original mechanical properties. Another source of uncertainty between the research works is a consequence of the different research approaches: some have investigated only the effect of the time passing (therefore, aging), others consider the aging effect together with other effects, like the state of conservation and the duration of load. The main interest of the researchers was in the bending properties variation, while for other mechanical properties less information is available. In this paper, the results of several research works are presented and analysed regarding the differences in the mechanical properties for elements with different age levels. Moreover, recommendations for future research are included attending to the conclusions drawn from the analysed literature

Repairing of a timber truss through two different techniques using timber elements and screwed metal plates

Pre-print versionStructural reinforcement of timber buildings may be needed due to different reasons such as change of use, deterioration due to lack of maintenance, exceptional damaging incidents or loading, after changes in regulatory specifications, or interventions to increase structural resistance. In this work, two different techniques were considered for repairing a timber truss that was previously assessed on laboratory (test facilities of University of Minho) and taken up to failure during a load-carrying test. A collar beam truss, with more than one hundred years, was tested considering a vertical point load on each main rafter. Failure of the timber truss was located in the sections of the rafters near the loading positions by bending. Repairing techniques, based on the use of timber elements for one of the rafters and on screwed metal plates for the other rafter, were evaluated and compared to the original unstrengthened condition. The efficiency of the combined repairing techniques was evaluated taking into consideration the structural performance of the collar truss, namely its displacement and ultimate load capacity. In this paper, the results of the experimental tests are discussed attending to the analytical calculation of the contribution of the repairing techniques. Also, the different failure scenarios, for original and strengthened truss, were analyzed and compared.The first and second authors would like to express their gratitude for the grant provided by training school: Assessment and reinforcement of timber elements and structures (Guimaraes, Portugal) within the scope of FP1101 and RILEM TC 245. The present work was made within a homework task regarding that training school. The authors acknowledge the support of the Structural Lab from University of Minho (test facilities). The assistance of Eng. Ricardo Braz from Rotho Blaas in the definition of the repair solutions and material provided are acknowledged. The authors acknowledge also the support and assistance of Augusto de Oliveira Ferreira e Companhia Lda (AOF). This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme-COMPETE and by national funds through FCT-Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633

Thrombophilia testing in the real-world clinical setting of thrombosis centres taking part in the italian start 2-register

BACKGROUND: Even though it rarely influences venous thromboembolism (VTE) treatment and the fact that it is generally discouraged, thrombophilia testing is still largely prescribed. We assessed: 1) whether/how frequently Italian thrombosis centres requested thrombophilia testing; 2) what results were obtained; and 3) if the results affected treatment and clinical results.MATERIALS AND METHODS: We examined data from 4,826 VTE patients enrolled by 19 clinical centres participating in the START 2-Register.RESULTS: 57.2% of patients were tested. Numbers varied widely among centres (2.9-99.7%). Thrombophilic alterations were recorded in 18.2% of patients and the percentage of positive results was inversely correlated with that of patients tested. Significantly less patients with deep vein thrombosis (DVT) were tested, whereas more were tested when the event was idiopathic, presenting as isolated pulmonary embolism (PE), or in unusual sites. Patients with thrombophilic alterations were younger, more frequently treated with direct oral anticoagulants (DOACs), with lower mortality and less frequently discontinued anticoagulation. DOACs were more frequently prescribed in patients with heterozygous Factor V (FV) Leiden or prothrombin mutations, whereas vitamin K antagonists were preferred in patients with inhibitor deficiencies, combined alterations or antiphospholipid syndrome (APLS). There was no difference in duration of treatment among those with or without alterations, though more APLS patients received an extended treatment course. Bleeding and thrombotic complications occurred with a similar and fairly low incidence in patients with or without thrombophilic alterations.DISCUSSION: Although general testing for thrombophilia in VTE patients is currently discouraged, more than half of the VTE patients included in the START2-Register were tested. However, there were marked differences in practice between Italian thrombosis centres. About 60% of all patients with alterations were treated with DOACs, confirming that DOACs can be a useful option for treatment of thrombophilic VTE patients, with the exclusion of those with APLS

Bleeding and thrombotic complications during treatment with direct oral anticoagulants or vitamin K antagonists in venous thromboembolic patients included in the prospective, observational START2-register

Objective The proportion and characteristics of Italian patients affected by venous thromboembolism (VTE) treated with direct oral anticoagulants (DOACs) or vitamin K antagonists (VKAs), and complications occurring during follow-up.Design A prospective cohort of 2728 VTE patients included in the Survey on anticoagulaTed pAtients RegisTer (START2-Register) from January 2014 to June 2018 was investigated. Characteristics of patients, type of treatment and complications occurring during 2962 years of follow-up were analysed.Setting About 60 Italian anticoagulation and thrombosis centres participated in the observational START2-RegisterParticipants 2728 adult patients with VTE of a lower limb and/or pulmonary embolism (PE), with a follow-up after the initial phase treatment.Interventions Patients could receive DOACs or VKAs; both prescribed by the National and Regional Health Systems for patients with VTE.Outcomes measures Efficacy: rate of VTE recurrence (all thrombotic complications were also recorded). Safety: the rate of major and clinically relevant non-major bleeding events.Results Almost 80% of patients were treated with DOACs. The prevalence of symptomatic PE and impaired renal function was higher in patients receiving VKAs. Duration of anticoagulation was >180 days in approximately 70% of patients. Bleeding events were similar in both treatment groups. The overall eventuality of recurrence was significantly higher in DOAC cohorts versus VKA cohorts (HR 2.15 (1.14–4.06), p=0.018); the difference was almost completely due to recurrences occurring during extended treatment (2.73% DOAC vs 0.49% VKA, p<0.0001). All-cause mortality was higher in VKA-treated (5.9%) than in DOAC-treated patients (2.6%, p<0.001).Conclusion Italian centres treat most patients with VTE with DOACs and prefer VKA for those with more serious clinical conditions. Recurrences were significantly more frequent in DOAC-treated patients due to increased incidence after 180 days of treatment, probably due to reduced adherence to treatment. These results underline the importance of structured surveillance of DOAC-treated patients with VTE to strengthen treatment adherence during extended therapy