Capacity of interlocking stub column with cement mortar infill under axial compression load

This paper presents an experimental investigation on interlocking stub column with cement mortar infill subjected to axial compression load. The interlocking stub column is produced by using load bearing interlocking blocks arranged in vertical direction to form a square shaped column section. The objective of this study is to investigate the compression capacity and failure mode of the column. Six specimens were tested in this study under axial compression load using universal testing machine. From the experiments, all specimens failed in crushing of interlocking blocks. The ultimate load carrying capacity for all tested specimens are in the range of 461.6kN to 577.6kN

Engineering properties of bio-inspired cement mortar containing seashell powder

Cement mortar is a semi liquid formed by a composite of cement, sand and water. Generally, cement mortar is used as a medium for bricks laying in construction. Nowadays, the properties of various types of waste materials are studied as construction material in buildings such as blast furnace ash, fly ash and palm oil fuel ash. In this study, the seashell is used as a replacement of building material in cement mortar.Seashell consists of high amount of calcium carbonate that provides remarkable mechanical properties and suitable to be used as building material. The engineering properties of cement mortar is studied, which including the compressive strength, flexural strength, splitting tensile strength, durability, modulus of elasticity in compression, setting time, water absorption and shrinkage. Cockle (Anadaragranosa) and mussel (Pernaviridis) are selected to replace the sand in the cement mortar with a ratio of 0, 25, 50, 75, and 100 percent by total weight of sand. A total number of 2800samples are prepared and tested up to 1 year and subjected to four exposure conditions, which are water, air, natural weather and wet-dry cycle.The replacement of seashell in cement mortar is likely to increase its engineering properties especially compressive strength due to high amount of calcium carbonate.The replacement of seashell in cement mortar will reduce the construction cost, improve the engineering properties of mortar and can be applied in various mortar applications

Monotonic behaviour of beam-to-column connections with double channel cold-formed steel sections

Cold-formed steel is a lightweight construction material generally in C or Z shaped produced by cold rolling from strip steel. It can be applied in the Industrialized Building System (IBS) in order to reduce the time and cost in construction project. Partial strength connection is a connection whereby the moment resistance of the connection is less than that of the moment capacity of the connected beam. In this paper, Numerical simulation is conducted by using ANSYS Workbench 14.0 in order to predict the structural behaviors of cold formed steel partial strength connection. The objective of this study is to develop moment rotation curve for flange-web-cleat connection using double channel cold formed steel section under monotonic loading. Experiment test results are then used to compare and validate the results from the finite element modeling. This study aims to understand the behaviour of cold-formed steel connections under monotonic loading. The beam section of 1.5-meter length and column of 3-meter length is modeled in this study. Three different beam depth have been selected in this study, which is 150mm, and the depth of column section is fix to 250mm. Brackets connections were chosen and all connections were formed using bolts. The monotonic load is applied at 1000mm from the column surface. The stiffness and moment capacity is obtained from the moment rotation curve which plotted from the modeling results. As a conclusion, The FEM initial results showed good agreement with experimental results

Temperature rise of cold-formed steel built-up back-to-back column under standard fire

Cold-formed steel (CFS) has been used for various applications in building structure. Due to its many advantages, the uses of CFS can be widened to build new or to renovate existing single one or two families private homes. However, the fire resistance of the CFS is a critical issue whereby inclined to lose its vigour when it is exposed to fire, compared to hot-rolled steel member. This study takes the opportunity to investigate the application of this material as column members subjected to the standard fire. Four columns were tested. One column with a static load was tested under the ambient condition, while the three other columns were loaded at different degrees of utilisation under the standard ISO 834 fire conditions. The increases of temperature on the column surface were monitored using thermocouple Type K and the analyses of this thermocouple reading was taken to evaluate the mean temperature of the column. The temperature behaviours of back-to-back column for all degrees of utilisation showed that, the web was a lower temperature compared to the flange due to the greater thickness of the web. Meanwhile, the failure temperature of the CFS could reach up to 651.0 ºC for 30.0 % degree of utilisation with 8.0 minutes of resistant time

Force and deformation behaviour of roof truss system with cold-formed steel channel section

Cold-formed steel is widely used in Malaysia’s construction for roof truss structures. This study aims to investigate the force and deformation behaviour of a roof truss system and evaluate the results from analytical and experimental investigation. One roof truss was constructed by using LC7510 cold-formed steel channel which is 5.4m long and 0.651m height with angle about 20 degree and eight concentrated loads were acting on the top chord. The deflection of the roof truss was analyzed by LVDT’s. STAAD Pro was used to carry out the analytical investigation. Three models with three load cases been modeled and compared with actual roof truss. The critical load case is Load Case 2 which leaded to higher deflections. The percentage difference on deflection between Model 1 with Load Case 2 is 15.4% and the roof truss failed on connection direct to the support due to buckling

Survival and quality of life in incident systemic sclerosis-related pulmonary arterial hypertension

Background: Pulmonary arterial hypertension (PAH) is a leading cause of mortality in systemic sclerosis (SSc). We sought to determine survival, predictors of mortality, and health-related quality of life (HRQoL) related to PAH in a large SSc cohort with PAH. Methods: We studied consecutive SSc patients with newly diagnosed (incident) World Health Organization (WHO) Group 1 PAH enrolled in a prospective cohort between 2009 and 2015. Survival methods were used to determine age and sex-adjusted standardised mortality ratio (SMR) and years of life lost (YLL), and to identify predictors of mortality. HRQoL was measured using the Short form 36 (SF-36) instrument. Results: Among 132 SSc-PAH patients (112 female (85%); mean age 62 ± 11 years), 60 (45.5%) died, with a median (±IQR) survival time from PAH diagnosis of 4.0 (2.2-6.2) years. Median (±IQR) follow up from study enrolment was 3.8 (1.6-5.8) years. The SMR for patients with SSc-PAH was 5.8 (95% CI 4.3-7.8), with YLL of 15.2 years (95% CI 12.3-18.1). Combination PAH therapy had a survival advantage (p < 0.001) compared with monotherapy, as did anticoagulation compared with no anticoagulation (p < 0.003). Furthermore, combination PAH therapy together with anticoagulation had a survival benefit compared with monotherapy with or without anticoagulation and combination therapy without anticoagulation (hazard ratio 0.28, 95% CI 0.1-0.7). Older age at PAH diagnosis (p = 0.03), mild co-existent interstitial lung disease (ILD) (p = 0.01), worse WHO functional class (p = 0.03) and higher mean pulmonary arterial pressure at PAH diagnosis (p = 0.001), and digital ulcers (p = 0.01) were independent predictors of mortality. Conclusions: Despite the significant benefits conferred by advanced PAH therapies suggested in this study, the median survival in SSc PAH remains short at only 4 years.Kathleen Morrisroe, Wendy Stevens, Molla Huq, David Prior, Jo Sahhar, Gene-Siew Ngian, David Celermajer, Jane Zochling, Susanna Proudman, Mandana NikpourEmail author and the Australian Scleroderma Interest Group (ASIG

Epidemiology and disease characteristics of systemic sclerosis-related pulmonary arterial hypertension: results from a real-life screening programme

Pulmonary arterial hypertension (PAH) is the leading cause of death in systemic sclerosis (SSc). Annual screening with echocardiogram (ECHO) is recommended. We present the methodological aspects of a PAH screening programme in a large Australian SSc cohort, the epidemiology of SSc-PAH in this cohort, and an evaluation of factors influencing physician adherence to PAH screening guidelines.Patient characteristics and results of PAH screening were determined in all patients enrolled in a SSc longitudinal cohort study. Adherence to PAH screening guidelines was assessed by a survey of Australian rheumatologists. Summary statistics, chi-square tests, univariate and multivariable logistic regression were used to determine the associations of risk factors with PAH.Among 1636 patients with SSc, 194 (11.9%) had PAH proven by right-heart catheter. Of these, 160 were detected by screening. The annual incidence of PAH was 1.4%. Patients with PAH diagnosed on subsequent screens, compared with patients in whom PAH was diagnosed on first screen, were more likely to have diffuse SSc (p = 0.03), be in a better World Health Organisation (WHO) Functional Class at PAH diagnosis (p = 0.01) and have less advanced PAH evidenced by higher mean six-minute walk distance (p = 0.03), lower mean pulmonary arterial pressure (p = 0.009), lower mean pulmonary vascular resistance (p = 0.006) and fewer non-trivial pericardial effusions (p = 0.03). Adherence to annual PAH screening using an ECHO-based algorithm was poor among Australian rheumatologists, with less than half screening their patients with SSc of more than ten years disease duration.PAH is a common complication of SSc. Physician adherence to PAH screening recommendations remains poor. Identifying modifiable barriers to screening may improve adherence and ultimately patient outcomes.Kathleen Morrisroe, Wendy Stevens, Joanne Sahhar, Candice Rabusa, Mandana Nikpour, Susanna Proudman and the Australian Scleroderma Interest Group (ASIG

A new fault-tolerant configuration for the Cambridge Ring: the Hierarchical Ring-Star

The primary objective of this research is to look at ways of resolving the reliability problems of the Cambridge Ring local area network system. The result is a novel design to enhance the Cambridge Ring with fault tolerance by introducing redundant communication paths with dynamic reconfiguration. The proposed Ring-Star system combines the advantages of ring and star networks to create a network which is topologically resilient while retaining the efficient communication advantage of rings. [Continues.

Burkholderia pseudomallei Isolates from Sarawak, Malaysian Borneo, Are Predominantly Susceptible to Aminoglycosides and Macrolides

Melioidosis is a potentially fatal disease caused by the saprophytic bacterium Burkholderia pseudomallei. Resistance to gentamicin is generally a hallmark of B. pseudomallei, and gentamicin is a selective agent in media used for diagnosis of melioidosis. In this study, we determined the prevalence and mechanism of gentamicin susceptibility found in B. pseudomallei isolates from Sarawak, Malaysian Borneo. We performed multilocus sequence typing and antibiotic susceptibility testing on 44 B. pseudomallei clinical isolates from melioidosis patients in Sarawak district hospitals. Whole-genome sequencing was used to identify the mechanism of gentamicin susceptibility. A novel allelic-specific PCR was designed to differentiate gentamicin-sensitive isolates from wild-type B. pseudomallei. A reversion assay was performed to confirm the involvement of this mechanism in gentamicin susceptibility. A substantial proportion (86%) of B. pseudomallei clinical isolates in Sarawak, Malaysian Borneo, were found to be susceptible to the aminoglycoside gentamicin, a rare occurrence in other regions where B. pseudomallei is endemic. Gentamicin sensitivity was restricted to genetically related strains belonging to sequence type 881 or its single-locus variant, sequence type 997. Whole-genome sequencing identified a novel nonsynonymous mutation within amrB, encoding an essential component of the AmrAB-OprA multidrug efflux pump. We confirmed the role of this mutation in conferring aminoglycoside and macrolide sensitivity by reversion of this mutation to the wild-type sequence. Our study demonstrates that alternative B. pseudomallei selective media without gentamicin are needed for accurate melioidosis laboratory diagnosis in Sarawak. This finding may also have implications for environmental sampling of other locations to test for B. pseudomallei endemicity