Judul: Kekuatan sambungan batang kayu-pelat baja dengan beberapa jenis alat sambung tipe dowel dan ketebalan batang kayu Acacia mangium Wild.
Abstrak: Wood joint is a joint that fasten two or more lumber together by using the mechanical joint such as nails, bolts, connectors or using grafting in the form of structural adhesive. The purpose of this study is to know the influence of the type of fasteners and the thickness of the beam to the strength of beams with steel plate joint on Acacia mangium wood. This study uses three types of dowel type fasteners, ie nails, bamboo pegs and wooden pegs. Wood that used in this study is Acacia mangium wood with variations in thickness from 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm and 5.5 cm, while the wood used to be a wooden pegs is bangkirai wood. This joint technique use a steel plate as connection plate. Testing is done by putting pressure tap on the joint. The direction of loading is an axial direction of the long wooden beams and perpendicular to the length of the fasteners. The results showed that the type of fasteners and thickness of the beam give effect to the strength of the beam-steel plate joint. Joint with nails has the highest allowable load on mangium wood-steel plates joint, followed by a bamboo pegs, and the lowest is the wooden pegs. There is a general tendency that the allowable load of mangium wood-steel plate joint will increase with increasing the beam thickness. Thus, under the provisions of limit displacement set by the the United States, Australia and Indonesia, respectively in displacement of 0.38 mm, 0.80 mm and 1.50 mm, the allowable load of mangium wood-steel plate joint in the same diameters of nails, bamboo pegs and wood pegs (5.2 mm) differ according to the thickness of the beam.
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Judul: Kekuatan sambungan baut double shear berpelat sisi baja pada kayu Sengon, Bintangur dan Kapur menurut berbagai sesaran
Abstrak: INTRODUCTION : Wood as raw material needs continue to increase for various purposes. Similarly, for component building materials or construction materials. As a construction materials, wood has been known to the public long before the public to use concrete or steel. In use as building construction materials, wood should be able to withstand various kinds of expenses in the period planned and have sufficient durability and has a cross-sectional size or length of span in accordance with the planning. Cross-sectional size or long span timber in accordance with the plans for building construction is very difficult to obtain. This is because of the limited size of available timber in the market so it needs a connection. MATERIAL AND METHOD : The main material used is wood sorts Sengon (Paraserianthes falcataria (L). Nielsen), Bintangur (Calophyllum inophyllum L.) and Kapur (Dryobalanops sp.), bolts and steel plates. Wood used as a mechanical connection that unites steel plate with wood screws that penetrate the system using the plate-wood-plate which is the tightened with a nut for strong connection strength is based on ASTM D5652-95 with a direction perpendicular to the bolt load. Other properties tested were water content, density and maximum compressive strength parallel to grain. Tests physical properties following the ASTM D143-94, while the mechanical properties following the BS-373 1957. RESULT : Double-shear strength bolt connection between the wood with steel plates in general are influenced by density of wood. The higher value density then the value of the power connection (which is expressed with the total load) and the value of load per bolt will be higher as well. Total expenses will increase with the number of bolts except from 6 to 8 pieces,while the load per bolt is not affected by the number of bolts. Total load and load per bolt tends to increase with increasing bolt diameter from 6.4 mm to 7.9 mm,but decreases when the diameter increased to 9.4 mm bolts.
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Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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