Optimisation of calcium silicate and sand cement bricks in masonary bearing walls / Kartini Kamaruddin and Siti Hawa Hamzah

Design and construction of buildings used to be on framed structure incorporating reinforced concrete, steel or timber as structural member to transmit load to the foundation. Bricks are normally used as infill materials in these framed structures. However, research has shown that bricks can also be used as external and internal masonry bearing walls. With the use of structural masonry construction method, cheaper and faster construction can be achieved. Savings are obtained by using less formwork and reinforcing steel, reducing construction time as lesser frames or none are used, and eliminating waiting time for the structural concrete to cure or gain their strength. Calcium silicate and sand cement bricks were tested for their mechanical properties. Investigations were carried out on six masonry bearing walls. Each unit measured 1000 mm × 1000 mm and a half brick thick. The structural behaviour due to compressive axial load was investigated and it shows that both bricks satisfy the requirement as load bearing wall. However, the study concluded that sand cement brick wall showed better performance, with maximum lateral displacement of 3.81mm, vertical deflection of 6.63 mm and ultimate load of 448.13 kN

Flexural crack propagation in steel fibre concrete beam / Nur Anisa Athirah Rosli

The inclusion of steel fibres in the concrete matrix is the best alternative to control crack propagation along the failure plane. For decades, some of the studies carried out on steel fibre reinforced concrete beam (SFRC) had highlighted the effect of fibre dosage, fibre type and fibre size towards the mechanical behaviour of concrete, however, there are still uncertainties as to what extent does hooked end fibres with size of 35 mm and 60 mm at 40 kg/m3 and 80 kg/m3 respectively affected the flexural strength and crack produced in concrete. Thus, this study intends to investigate both effect of fibre dosage and fibre length of hooked end steel fibre towards flexural strength and crack propagation in 75 mm x 75 mm x 300 mm fibred concrete beam. In the study, hooked end steel fibres were incorporated into 12 beams having specified strength of 30 MPa. Meanwhile, the flexural strength of concrete was tested using Universal Testing Machine (UTM) under three point bending test. The incorporation of fibre at higher dosage with longer length has resulted in better results in terms of flexural strength and the crack produced as compared to the usage of short fibre at lower dosag

PSSDB load bearing wall with window opening - effect of butt joint in dryboard / Prof Madya Ir. Siti Hawa Hamzah …[et al.]

Profiled steel sheet dry board or PSSDB system is a new innovative composite construction system with a potential to be expanded in application as an alternative to flooring, wall unit and roofing system. In this study, load-bearing walls with window opening were constructed using PSSDB. The investigation was carried out experimentally to determine the structural behaviour and to see the effect of butt joint in the dry boards. The PSSDB load bearing wall system consists of two dry boards (Cemboards) attached to profiled steel sheet (Bondek II), the core of panel, using mechanical connectors (self-drill screws). Several aspects such as literature review, testing method and analysis of results were included in this research. The samples tested were three (3) numbers of PSSDB walls with window opening and butt joint in the dry boards, and three (3) numbers of PSSDB walls with window opening but without butt joint in the dry boards. The size of each sample is 1000 mm high x 1320 mm wide x 78 mm thick with window opening of size 400 mm x 400 mm x 78 mm. The connectors were fixed at a 100 mm center to center in the longitudinal axis. The samples were subjected to axial compressive load and comparisons were made between the two sets of samples. The average value of the ultimate load capacity for PSSDB load bearing wall with butt joint was* found to be 286 kN, while that for the samples of PSSDB load bearing wall without butt joint was 260 kN. The maximum lateral deflection values for both types of PSSDB walls were 10.7 mm and 13.5 mm respectively. Significant effect of butt joint in dry board were seen in the reduced number of cracks by about 33% in comparison to that without butt joint

Seismic Perfromance On Multi-Storey Precast Buildings (IBS) In Malaysia Subjected To Long-Distant Earthquake Excitation / Nor Hayati Abdul Hamid … [et_al.]

Seismic performance of the reinforced concrete buildings in Malaysia need to examine their structural components under earthquakes excitation. The sub-assemblage of fullscale precast hollow core slabs together with supporting beams are designed, constructed, calibrated and tested under vertical cyclic loadings. The incremental drifts are applied at the end of the cantilever slabs. The load failure, mode of failure and structural damages are recorded and observed during experimental work. Initially, the cracks start from the joints and propagated on top of the slabs and finally, the slab snapped at middle together with delimination of the bottom fibre of the slab. Another experimental work is conducted on three sets of half-scale beam-column joint with different arrangements of reinforcement bars at the joints. These specimens are attached to the foundation beams and clamped to strong floor using eight high yield threaded rods of diameters 30mm. The specimens are designed, constructed and tested under reversible vertical cyclic loading until collapse. The joint with cross-bracing suffers the least damage as compare to others joints. By using the same specimens, the next step is to design the column-foundation joints under lateral cyclic loadings. Tension lateral cyclic loading is applied at top of the column with drifts of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5% at 2 cycles for each drift. Similar pattern of cracks and damages observed during experimental work as compared to the actual damages occurred during earthquake excitation. The first damage is due to unconfined concrete occurred between foundation beam and beamcolumn joint. The second damage is due to plastic hinge zone mechanism which occurs at column-foundation interfaces. These damages are due to the insufficient of longitudinal bars, the spacing between the stirrups are wider and spalling of concrete (lo

The effect of butt joint on the structural behaviour of PSSDB wall panel / Siti Hawa Hamzah ... [et al.]

An experimental investigation was carried out to determine the effect of butt joint on the structural behaviour of profiled steel sheet dry board (PSSDB) load bearing wall with window opening. The samples tested were three (3) PSSDB walls with window opening and butt joint in the dry boards, and three (3) PSSDB walls with window opening but without butt joint in the dry boards. The samples were subjected to axial compressive load and comparisons were made between the two sets of samples. The average value of the ultimate load capacity for PSSDB load bearing wall with butt joint was found to be 286 kN, while that for the samples of PSSDB load bearing wall without butt joint was 260 kN. The average maximum lateral deflection values for both types of PSSDB walls were 8.9 mm and 13 mm respectively. Significant difference due to butt joint in dry board was seen in the reduced number of cracks by about 33 % in comparison to that without butt joint

Seismic performance of beam-column corbel connections (IBS) in the existing precast reinforced concrete frame under reversible lateral cyclic loading / Prof. Madya Dr. Nor Hayati Abdul Hamid @ Zulkurnail, Prof. Ir. Dr. Siti Hawa Hamzah and Kay Dora Abd Ghani

Industrialized Building System (IBS) is actively promoted by CIDB (Construction Industry Development Board) in the construction industries in Malaysia. The main reasons are to overcome the dilemma pertaining to construction productivity, quality of construction products and shortage of skilled workers. In addition to the above matter, there are some advantages of using IBS to reduce manpower, shortening construction period, all weather construction and maintaining the quality of construction (Badir et. al., 2002). IBS has been used in the construction of houses, high-rise condominiums, hypermarkets, apartments, shopping complexes, office buildings and others. Furthermore, the construction of these buildings using IBS as compared to cast-in-place methods are safer in term of construction aspects, quality of material and structural performance (Pampanin, 2003). However, the safety of this system from structure stability aspect is still questionable if it is not properly designed in accordance to seismic code of practice, especially when these buildings were experience higher ground shaking or earthquake attack; either locally or in the neighbouring countries. Earthquakes occurred in Banda Acheh, Sumatera on December 2004 with 9.2 Scale Richter had triggered some tremors and shaking of the high-rise buildings especially in Penang, Klang Valley, Putrajaya and other parts of West Coast of Malaysia. There were some minor cracks in some of reinforced concrete buildings in Malaysia following these earthquakes. Recent earthquake which happened on 25* October 2010 in Mentawai Island, Indonesia with 7.5 Scale Richter has destroyed more than 150 buildings and more than 500 peoples were killed in the tsunami caused by this earthquake event. Although Malaysia, Singapore and Thailand (which are located within Sunda Plate) are categorized as low seismic regions due to its location of about 650km from the Sunda trench, the movements of neighbouring tectonic plates such as India and Australia Plates with velocity 7cm/year towards Malaysia could develop tremor among residents in multi-storey and high-rise buildings in Malaysia (Hamid et. al., 2010)

Bending strength of steel fibre reinforced concrete ribbed slab panel / Amir Syafiq Samsudin … [et al.].

Nowadays, demands in the application of fibre in concrete increase gradually as an engineering material. Rapid cost increment of material causes the increase in demand of new technology that provides safe, efficient and economical design for the present and future application. The introduction ofribbed slab reduces concrete materials and thusthe cost, but the strength of the structure also reduces due to the reducing of material. Steel fibre reinforced concrete (SFRC) has the ability to maintain a part of its tensile strength prior to crack in order to resist more loading compared to conventional concrete. Meanwhile, the ribbed slab can help in material reduction. This research investigated on the bending strength of 2-ribbed and 3-ribbed concrete slab with steel fibre reinforcement under static loading with a span of 1500 mm and 1000 mm x 75 mm in cross section. An amount of 40 kg/m steel fibre of all total concrete volume was used as reinforcement instead of conventional bars with concrete grade 30 N/mm2 . The slab wastested underthree-point bending. Load versus deflection curve was plotted to illustrate the result and to compare the deflection between control and ribbed slab. Thisresearch showsthat SFRCRibbed Slab capable to withstand the same amount of load as normal slab structure, although the concrete volume reduces up to 20%

Preliminary investigation on the flexural behaviour of steel fibre reinforced self-compacting concrete ribbed slab / Nur Aiman Suparlan … [et al.]

A ribbed slab structure has the advantage in the reduction of concrete volume in between the ribs resulting in a lower structural self-weight. In order to overcome the drawbacks in the construction process, the application of steel fibre self-compacting concrete (SCFRC) is seen as an alternative material to be used in the slab. This preliminary investigation was carried out to investigate the flexural behaviour of steel fibre selfcompacting concrete (SCFRC) as the main material in ribbed slab omitting the conventional reinforcements. Two samples of ribbed slab were prepared for this preliminary study; 2-ribbed and 3-ribbed in 1 m width to identify the effect of the geometry to the slab’s flexural behaviour. The dimension of both samples is 2.5 m x 1 m with 150 mm thickness. The compressive strength of the mix is 48.6 MPa based on the cubes tested at 28 days. Load was applied to failure by using the four point bending test set-up with simple support condition. The result of the experiment recorded ultimate load carrying capacity at 30.68 kN for the 2-ribbed slab and 25.52 kN for 3-ribbed slab. From the results, the ultimate load of the 2-ribbed sample exceeds 3-ribbed by approximately 20%. This proved that even with lower concrete volume, the sample can still withstand an almost similar ultimate load. Cracks was also observed and recorded with the maximum crack width of 2 mm. It can be concluded that the steel fibres do have the potential to withstand flexural loadings. Steel fibre reduces macro-crack forming into micro-cracks and improves concrete ductility, as well as improvement in deflection. This shows that steel fibre reinforced self-compacting concrete is practical as it offers good concrete properties as well as it can be mixed, placed easier without compaction

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Determining the clonality and significance of coagulase-negative staphylococci isolated from blood cultures in HUSM

Coagulase-Negative Staphylococci (CoNS) is a group of microorganisms that are increasingly implicated as a cause of significant infection and has emerged as the most frequent cause of nosocomial bloodstream infection. CoNS species are nonnal skin flora and, it can be difficult to determine if CoNS species isolated from blood cultures reflect infection or microbial contamination. At the moment, pulsed-field gel electrophoresis (PFGE) is considered as a gold standard to diagnose the significance of CoNS isolated from blood cultures. In this study, significance of repeated CoNS isolated from blood cultures were evaluated by species identification, antibiogram and a molecular method, PFGE. A total of 101 pairs of Coagulase-Negative Staphylococci were analyzed during this period of study. These isolates were identified to the species level by API Staph ID. Out of 101 pairs(, only 84 pairs (83.1%) of CoNs identified were similar species. These 84 pairs were further analyzed by pulsed-field gel electrophoresis (PFGE) to detennine its clonality (genotypic). However only 33 pairs had eligible PFGE result for interpretation In this study, Staphylococcus epidermidis was the predominant species isolated (52.5%), followed by S.capitis (10.4%) and S.chromogenes (1.9%). The percentage of methicillinresistant CoNS was higher (68.68%) as compared to methicillin-sensitive CoNS. The percentage of same phenotype with same antibiogram pattern (40.7%) was lower as compared to same phenotype and different antibiogram pattern (59.3%). There was a significant association between same phenotype and same antibiogram pattern. Out of 33 pairs of CoNS analyzed, 87.9% (29 pairs) had indistinguishable patterns which denote the same bacterial strains. However the association between phenotypic and genotypic cannot be made because due to failure to maintain reproducible PFGE results, hence resulted in insignificant statistical findings. Overall laboratory concordance case was defined as a case which were concordant for the triple tests conducted: phenotypic, antibiogram pattern and genotypic. Out of 33 pairs of CoNS with PFGE results, 14 cases (42.4%) were concordant cases which represent laboratory true bacteraemia and 19 cases (57.6%) were regarded as contaminants. In this study, there was significant association between same phenotype and antibiotic treatment. The percentage of those who had antibiotic treatment and same phenotype was higher (90.9%) as compared to those without antibiotic treatment (9.1%). There was significant association for leukocyte count, nosocomial infection and antibiotic treatment with antibiogram pattern. The association of laboratory concordance cases with clinical parameters showed significant association between laboratory concordance cases with blood pressure, leukocyte count and antibiotic treatment. All clinical parameters were not significantly associated with concordance genotype. The outcome of this study showed that genotype by pulsed-field gel electrophoresis (PFGE) failed to show any association with clinical bacteraemia by statistical calculation due to small sample siz