Judul: The Strength of Betung Bamboo to Withstand Normal Force Compression and Tension
Abstrak: Bambu merupakan hasil hutan yang multiguna yaitu bahan baku mebel, kerajinan, alat musik, dan konstruksi. Penelitian ini bertujuan untuk mengukur sifat mekanis bambu betung yaitu kekuatan tekan sejajar serat, tarik sejajar serat, dan tarik tegak lurus serat serta menganalisis nilai 5% batas bawahnya. Ukuran contoh uji dan pengujian sifat mekanis mengacu pada BS ISO 22157:2019. Pengujian tekan sejajar dan tarik tegak lurus serat menggunakan UTM SATEC/Baldwin sedangkan pengujian tarik sejajar serat menggunakan UTM Chun Yen. Analisis data menggunakan aplikasi Easyfit 5.5 untuk mendapatkan nilai 5% batas bawah tiap pengujian. Rata-rata kuat tekan sejajar serat yang diperoleh yaitu sebesar 53,0 N/mm², sedangkan nilai rata-rata kuat tarik sejajar sebesar 109 N/mm². Rata-rata kuat tarik tegak lurus dengan ukuran lubang uji 25 dan 40 mm sebesar 2,53 dan 1,19 N/mm², sedangkan nilai rata-rata MOE tekan dan MOE tarik sejajar serat yaitu sebesar 2674 dan 9542 N/mm². Nilai 5% batas bawah untuk kuat tekan sejajar serat sebesar 38,1 N/mm², tarik sejajar serat sebesar 61,8 N/mm², sedangkan untuk kuat tarik tegak lurus sebesar 0,60 N/mm². Nilai 5% batas bawah kuat tarik tegak lurus yang lemah, membuat bambu tidak disarankan untuk dimanfaatkan ke arah tegak lurus seratnya. Nilai 5% batas bawah MOE tekan dan MOE sejajar serat yang diperoleh sebesar 1105 dan 6076 N/mm². Kata kunci: betung, kekuatan, tarik, tekan, nilai estimasi, Bamboo is multifunctional forest products such as furnitures, crafts, music instruments, and construction material. This research aims to determine the mechanical properties of betung bamboo, specifically, compression strength parallel to fiber, tension strength parallel and perpendicular to fiber, and its 5% exclusion limit value. The sample size and mechanical properties testing refers to BS ISO 22157:2019. Compression and tension strength parallel to fiber tested using UTM SATEC/Baldwin while tension strength perpendicular to fiber tested using UTM Chun Yen. Data analysis used Easyfit 5.5 to obtain 5% exclusion limit value of each test. The average value of compression strength and tension strength parallel to fiber were 53,0 N/mm² and 109 N/mm², respectively. The average value of tension strength perpendicular to fiber for 25 and 40 mm testing hole were 2,53 and 1,19 N/mm², while average MOE value of compression and tension strength parallel to fiber were 2674 and 9542 N/mm², respectively. The 5% exclusion limit value of compression strength parallel to fiber was 38,1 N/mm², tension strength parallel to fiber 61,8 N/mm², and 0,60 N/mm² for tension strength in perpendicular grain. The 5% exclusion limit value of tension strength in perpendicular grain was too weak, and it makes bamboo is not recommended to use at this property. The 5% exclusion limit MOE value of compression and tension strength in parallel grain were 1105 and 6076 N/mm², respectively. Keyword: betung, compression, estimate value, strength, tension
Keyword: betung, compression, estimate value, strength, tension

Judul: Buckling Properties of Betung Bamboo (Dendrocalamus asper)
Abstrak: Bambu betung potensial digunakan sebagai konstruksi struktural. Tidak seperti bambu kolom pendek, kolom panjang dipengaruhi oleh peristiwa tekuk. Penelitian ini bertujuan untuk membuat rumus eksperimental hubungan antara angka kelangsingan dan faktor tekuk serta menentukan nilai faktor tekuk bambu betung pada berbagai angka kelangsingan. Bambu betung ditebang dari Jalan Huni Fakultas Kehutanan dan Lingkungan, Institut Pertanian Bogor dengan panjang 13-14 m yang dipotong menjadi dua bagian. Pengukuran kadar air, kerapatan, kerapatan linear, bentuk geometri dan kandungan cacat (dimensi, keruncingan, eccentricity, kelengkungan, ovality) mengacu pada BS ISO 19624:2018 tentang pemilahan buluh bambu. Uji t-test digunakan untuk membandingkan sifat fisis dan mekanis contoh uji berukuran pendek dan contoh uji berukuran panjang. Ukuran contoh uji pendek dan contoh uji panjang yaitu 6.05-15.81 cm dan 40-410.7 cm. Pengujian tekan contoh uji pendek dilakukan menggunakan alat UTM Shimadzu tipe UMH-30, sedangkan pengujian contoh uji panjang menggunakan alat UTM Baldwin dan alat uji tekuk ukuran panjang. Kedua pengujian dilakukan pembebanan secara vertical (sejajar serat). Pengolahan data menggunakan formula Rankin Gordon, Ylinen’s, Euler, Newlin Gahagan’s, dan Euler Johnson. Tekuk merupakan suatu jenis kegagalan yang disebabkan oleh ketidakstabilan suatu elemen struktur yang dipengaruhi oleh aksi (beban tekuk). Angka kelangsingan merupakan panjang tekuk dibagi dengan jari-jari inersia. Kerapatan dan kerapatan linear berhubungan erat dengan kuat tekan dan kapasitas tekan. Semakin tinggi nilai kerapatan dan kerapatan linear, maka nilai kuat tekan dan kapasitas tekan semakin tinggi. Korelasi antara kerapatan dengan kuat tekan dan kerapatan linear dengan kapasitas tekan dapat dibuktikan menggunakan analisis linear sederhana. Hasil penelitian menunjukkan kerapatan linear kondisi 12% dapat digunakan untuk menduga kapasitas tekan lebih baik daripada kerapatan kondisi 12%. Angka kelangsingan semakin tinggi berdampak pada nilai tekuk semakin rendah. Formula Ylinen’s cocok digunakan untuk menduga nilai tekuk pada berbagai angka kelangsingan., Betung bamboo is a potential material for structural construction. Unlike short bamboo columns, long columns are affected by buckling effect. This study aims to create an experimental formula of the relationship between the number of slenderness ratio and buckling factors and determine the value of the buckling factor of betung bamboo in various numbers of slenderness ratio. Betung bamboo is taken from Huni street, Faculty of Forestry and Environment, IPB University with 13-14 m length which is cut into two parts. Measurement of moisture content, density, linear mass, geometric shapes and defects (dimensions, taper, eccentricity, curvature, ovality) referred to BS ISO 19624:2018 about grading of bamboo culms. T-tests are used to compare the physical and mechanical properties of short test samples and long test samples. The short test sample and long test sample size are 6.05-15.81 cm and 40-410.7 cm length. The short test sample used UTM Shimadzu UMH-30 for compressive test, while the long test sample used UTM Baldwin and a long-size buckling test tool. Both tests were carried out vertically (parallel to grain). Data analysis used Rankin Gordon, Ylinen's, Euler's, Newlin Gahagan's, and Euler Johnson's formula. Buckling is a type of failure caused by the instability of a structural element affected by action (buckling load). Slenderness ratio is the length of bamboo culm divided by the radius of gyration. Linear mass and density are closely related
Keyword: slenderness ratio, betung, column, compressive, buckling

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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