Finite Element Modeling of the Transition Zone between Aggregat and Mortar in Concrete

Visual observations to the Interfacial Transition Zone (ITZ) between aggregate and mortar in concrete showed that this area differs significantly to the bulk mortar, further away from the ITZ. This ITZ has a higher porosity with a dissimilar crystal formation, therefore becoming the weak link in the material. In the past, concrete was seen as a two-phase material consisting of mortar and aggregates only. However, analyzing the material as a three-phase composite including the ITZ, will give a more realistic representation to its behavior. A Finite Element Model (FEM) was developed. The ITZ is modeled as a linkage element having a double spring, perpendicular and parallel to the ITZ surface. The individual load-deformation responses of these springs were obtained from laboratory tested specimens. Non-linearity is generated by evaluating the principal stresses at Gauss points, using the Kupfer-Hilsdorf-Rusch (1969) failure envelope and the CEB-FIB 2010 code. Iteration is conducted by the arc-length method developed by Riks-Wempners. The load-displacement curves resulted by the FEM were validated to laboratory tested specimens curves, to compare its effectiveness and asses the sensitivity of the model

In-space experiment on thermoacoustic convection heat transfer phenomenon-experiment definition

The definition phase of an in-space experiment in thermoacoustic convection (TAC) heat transfer phenomenon is completed and the results are presented and discussed in some detail. Background information, application and potential importance of TAC in heat transfer processes are discussed with particular focus on application in cryogenic fluid handling and storage in microgravity space environment. Also included are the discussion on TAC space experiment objectives, results of ground support experiments, hardware information, and technical specifications and drawings. The future plans and a schedule for the development of experiment hardware (Phase 1) and flight tests and post-flight analysis (Phase 3/4) are also presented. The specific experimental objectives are rapid heating of a compressible fluid and the measurement of the fluid temperature and pressure and the recording and analysis of the experimental data for the establishment of the importance of TAC heat transfer process. The ground experiments that were completed in support of the experiment definition included fluid temperature measurement by a modified shadowgraph method, surface temperature measurements by thermocouples, and fluid pressure measurements by strain-gage pressure transducers. These experiments verified the feasibility of the TAC in-space experiment, established the relevance and accuracy of the experimental results, and specified the nature of the analysis which will be carried out in the post-flight phase of the report

Studi Eksperimental Pengaruh Penambahan Abu Sekam Padi Nano Dan Bahan Tambah Superplasticizer Terhadap Kuat Tekan Beton

This research aimed to investigate effect of using nano materials rice husk ash and superplasticizer admixture to concrete compressive strength. Nano rice husk ash used as subtitute of pozzolan portland cement. Production of nano rice husk ash use Planetary Ball Milling with duration of milling for 1 hour. To determine effect of using nano materials rice husk ash dan superplasticizer admixture used variation percentage of materials nano rice husk ash such ash 5%, 10%, and 15% with or without superplasticizer admixture. Tests were conducted at 28 days with uniaxial loading (one-way). Result of this research indicate normal concrete without substitution of nano rice husk ash and without superplasticizer have highest of concrete compressive strength. Concrete with rice husk ash decreased in compressive strength because of rice husk ash absorb much water and increase the length of hydration process of cement in concrete mix. Although there is a decrease through this research is expected, nano techonology in civil engineering can more developed

Studi Eksperimental Pengaruh Konfigurasi Sengkang Pada Daerah Tekan Balok Beton Serat Bertulang

Concrete has relatively high compressive strength, in other hand higher concrete compression give more brittle of failure. There are several methods for improvement such as addition steel-fiber in concrete mix and confinement in the compression zone. This study present a further study on the influence of addition 0.5% steel-fiber of concrete volume to concrete mix and three specimen fiber concrete beams ware evaluated with three stirrup configuration (BF1, BF4, BF5) that concentrated in the compression zone. The study's analyze using a pure beding test with 2 point load of a simply supported beam. The variation of stirrup configuration concentrated at pure beding moment zone of beam. The result of this study, the addition of steel-fibers to the concrete mix increased the cylinder compression strength by 11,96%, The moment capacity of BF4 increased by 0,96% compered to BF1 in other hand the specimen BF5 reduce by 4,1% compered to BF1 ,The Stiffnes of BF4 increased 132,64% and BF5 increased by 25,44% compared to BF1,The Ductility of specimen BF4 increased by 148,01% and BF5 increased by 3.97% compared to BF1

Perencanaan Struktur Gedung Menara Bri Semarang

The structural of BRI tower building Semarang is designed in seismic zone of Semarang city, which is designed by using the Special Moment Resisting Frame System (SMRFS) based on ”Indonesian Concrete Code (SNI 03-2847-2002)”, while the analysis of earthquake load uses response spectrum method based on “Indonesian Seismic Code(SNI 03-1726-2012). The design structural of BRI tower building Semarang using“Capacity Design” concept. As for using this concept has purpose what if strong earthquake happens, that cause forms plastic hinge on structural elements which is desired appeared on the beams. To guarantee plastic hinge happens on the beams, so the columns must be designed stronger than the beams (Strong Column Weak Beam Concept). The analysis of the structure is using SAP2000 computer program version 14. As the result of calculations showed that structural element of BRI tower building is safe based on analyze

Penelitian Kuat Lentur Balok Susun Dari Kayu Glugu Dan Kayu Sengon

Kayu adalah bahan bangunan yang sering digunakan pada bangunan. Kayu keruing adalah salah satu jenis kayu yang banyak digunakan, namun harganya relatif mahal. Kayu glugu dan kayu sengon dapat menjadi bahan bangunan alternatif untuk menggantikan penggunaaan kayu keruing karena populasinya yang tinggi. Pengembangan teknologi yang digunakan dalam penelitian ini adalah balok kayu tersusun, dimana beberapa kayu dengan dimensi penampang tersendiri digabungkan menjadi satu penampang baru dengan cara direkatkan. Pada penelitian ini pengujian yang dilakukan adalah pengujian lentur full scale one point load. Hasilnya adalah kuat balok susun dapat melebihi kayu keruing sehingga dapat menggantikan kayu keruing yang digunakan sebagai elemen lentur. Benda uji berupa balok susun yang terdiri dari kayu glugu dan sengon berbentuk I (BS 1), balok susun dari kayu glugu dan sengon berbentuk persegi panjang (BS 2), balok susun 2 dari kayu glugu (G), balok susun 4 dari kayu sengon (S) dan balok dari kayu keruing (K). Balok susun kayu memiliki rasio luasan mendekati rasio luasan balok kayu keruing dengan ukuran 8 cm x 12 cm dan bentang bersih sepanjang 2 meter untuk kemudian dibandingkan kuat lenturnya. Pengeleman balok susun menggunakan lem bertipe Polivynyl Asetat (PVAc) yang relatif mudah didapat dengan merk FOX. Hasil pengujian pada benda uji balok susun kayu terbaik didapatkan dari benda uji balok susun 2 dari kayu glugu sebesar 24,674 KN yaitu lebih besar 7,605% dari beban maksimal rata-rata kayu keruing yaitu 22,93 KN. Biaya pembuatan benda uji glugu hanya sebesar 72,6% dari biaya kayu keruing pasaran di kota Semarang