Analytical modeling of 3D-printed reinforced concrete beams

Three-dimensional (3D) printing for cementitious materials such as concrete has become increasingly popular. Numerous research efforts have been undertaken to fabricate structural elements, such as beams, using 3D-printed concrete. Because the behavior of 3D-printed reinforced concrete (RC) beams is not well understood, research in this area is still ongoing to investigate the behavior and compare it with conventional RC beams. In this paper, the results of an analytical study using finite element software on 3D-printed RC beams are presented. The main challenge was to determine a constitutive material model of the 3D-printed concrete for nonlinear analysis that was quite different from normal concrete. The developed model was validated using the results from several past experimental tests on 3D-printed RC beams. The results showed that the analytical model can accurately predict the maximum flexural strengths of the 3D-printed RC beams. However, the analytical model overestimated the initial stiffness of the beams. Furthermore, several local failures, such as shear failure of nodal points and bond failure between rebars and concrete, could not be well simulated by the analytical model. Thus, future research is needed to correctly define the constitutive material model for 3D-printed RC beams

Analytical modeling of 3D-printed reinforced concrete beams

Three-dimensional (3D) printing for cementitious materials such as concrete has become increasingly popular. Numerous research efforts have been undertaken to fabricate structural elements, such as beams, using 3D-printed concrete. Because the behavior of 3D-printed reinforced concrete (RC) beams is not well understood, research in this area is still ongoing to investigate the behavior and compare it with conventional RC beams. In this paper, the results of an analytical study using finite element software on 3D-printed RC beams are presented. The main challenge was to determine a constitutive material model of the 3D-printed concrete for nonlinear analysis that was quite different from normal concrete. The developed model was validated using the results from several past experimental tests on 3D-printed RC beams. The results showed that the analytical model can accurately predict the maximum flexural strengths of the 3D-printed RC beams. However, the analytical model overestimated the initial stiffness of the beams. Furthermore, several local failures, such as shear failure of nodal points and bond failure between rebars and concrete, could not be well simulated by the analytical model. Thus, future research is needed to correctly define the constitutive material model for 3D-printed RC beams

Nonlinear finite element analyses of reinforced concrete beam-column joints subjected to cyclic loading

Interaction of forces and moments in a beam-column joint is complex and most of the time nonlinear. Thus, a simple, global model is insufficient to estimate the performance and behavior of the joint. Results from several nonlinear finite element analyses of beam-column joints using VecTor2 are presented herein. Four interior and two exterior beam-column joint models with three different types of failure were studied. The analysis results in terms of force-drift ratio curves and crack patterns were then compared to the experimental results. In general, the results obtained from VecTor2 were satisfactory, but in some cases the program could not accurately capture the strength degradation observed in the specimen with joint shear failure. Moreover, the crack patterns were not accurately captured. Nevertheless, VecTor2 can still estimate the peak forces well for all specimens in this study

Validation of nonlinear finite element model of reinforced concrete beams subjected to monotonic loading

The nonlinear behavior of reinforced concrete beams is complex due to their heterogenic properties and crack formations. Thus, a more accurate estimation through experimental testing and nonlinear finite element modeling is necessary to understand better such behavior. Experimental testing of a reinforced concrete beam subjected to monotonic loading was conducted in laboratory. The test specimen along with seven specimens from various literature were then modeled and analyzed using VecTor2 software to investigate the capability of the software in predicting the load-displacement curves and crack patterns of the specimens. The analysis results show that the finite element model used in VecTor2 software is able to predict well the load-displacement curves and crack patterns of the specimens failing in flexure and shear mechanisms

Validation of nonlinear finite element model of reinforced concrete beams subjected to monotonic loading

The nonlinear behavior of reinforced concrete beams is complex due to their heterogenic properties and crack formations. Thus, a more accurate estimation through experimental testing and nonlinear finite element modeling is necessary to understand better such behavior. Experimental testing of a reinforced concrete beam subjected to monotonic loading was conducted in laboratory. The test specimen along with seven specimens from various literature were then modeled and analyzed using VecTor2 software to investigate the capability of the software in predicting the load-displacement curves and crack patterns of the specimens. The analysis results show that the finite element model used in VecTor2 software is able to predict well the load-displacement curves and crack patterns of the specimens failing in flexure and shear mechanisms

Studi Eksperimen Karakteristik Kinerja Kincir Air sebagai Pembangkit Listrik Skala Mikrohidro

Masalah yang sering dijumpai di masyarakat dalam pemanfaatan sumber energi air pada saluran miring adalah masih sedikitnya jumlah ketersediaan kincir air yang bersekala mikro, karena untuk mendesain dan membuat kincir air ini perlu suatu kemampuan dan keahlian khusus. Pemanfaatan dan pengunaan kincir air pada saluran miring masih belum begitu optimal penggunaan dan pemakaiannya di Indonesia, hal tersebut dikarenakan masih minimnya  informasi tentang pemanfaatan dan pengaplikasian kincir air pada saluran miring dalam pemanfaatannya di lapangan. Penelitian ini memiliki suatu tujuan untuk mengetahui putaran kincir, daya listrik dan efisiensi sistem pada pembangkit listrik mikrohidro. Untuk mengetahui karakteristik kincir air pada saluran miring sebagai pembangkit listrik skala mikrohidro. Metode penelitian diawali dengan perancangan/ desain kincir air, kemudian dilanjutkan tahap pembuatan, tahap assembling dan installing, pengujian alat dan analisis, pengujian yang dilakukan meliputi uji karakteristik kincir air. Parameter penelitian yang diukur meliputi putaran generator, arus yang mengalir pada rangkaian, tegangan yang mengalir pada rangkaian, beban lampu yang diberikan, debit air yang mengenai sudu. Hasil Penelitian kincir air putaran kincir tertinggi pada ketinggian poros kincir 21 cm diatas bibir saluran adalah 40,3 rpm dengan beban lampu 20 Watt, sedangkan putaran kincir terendah pada ketinggian poros 29 cm diatas bibir saluran adalah 35,9 rpm dengan beban lampu 40 Watt. Daya listrik tertinggi pada ketinggian poros kincir 21 cm diatas bibir saluran adalah 4,68 Watt dengan beban lampu 20 Watt. Efisiensi sistem tertinggi pada ketinggian poros kincir 21 cm diatas bibir saluran adalah 0,284% dengan beban lampu 20 Watt

Pengujian Efisiensi Pasar Modal Bentuk Lemah di Bursa Efek Indonesia Periode Februari 2006-Juli 2009

Penelitian ini bertujuan untuk menguji efisiensi pasar modal bentuk lemah di Bursa Efek Indonesia (BEI). Penelitian ini terfokus dalam pembuktian efisiensi pasar bentuk lemah di Bursa Efek Indonesia periode Febuari 2006 – Juli 2009. Penelitian ini menggunakan dua metode pengujian untuk menguji efisiensi pasar modal bentuk lemah di Bursa Efek Indonesia. Uji yang digunakan dalam penelitian ini mencakup dua uji yaitu, Uji Otokorelasi dan Uji Runtun untuk mengetahui pasar modal Indonesia yang diwakili oleh Bursa Efek Indonesia telah efisien dalam bentuk lemah. Hasil penelitian ini menunjukkan bahwa dengan menggunakan Uji Otokorelasi dan Uji Runtun, pasar modal Indonesia yang diwakili oleh Bursa Efek Indonesia telah efisien dalam bentuk lemah. Hal ini menunjukan bahwa saham telah bergerak secara acak sehingga pemodal tidak dapat memperoleh keuntungan dengan menggunakan data historis

Analisis pengendalian internal atas siklus pendaftaran pada PT. "X" di Surabaya [CD-ROM]

Penelitian ini dilakukan dengan tujuan mengetahui gambaran penerapan pengendalian internal terhadap siklus pendapatan pada PT. “X” Surabaya serta untuk mengetahui faktor-faktor yang mungkin menghambat proses pengendalian internal terhadap siklus pendapatan. Jenis data yang dipakai adalah kualitatif dan sumber data diambil dari data siklus pendapatan pada PT. “X” Surabaya. Alat analisis yang digunakan adalah daftar wawancara yang ditujukan pada pihak pimpinan dan pihak staf yang berwenang. Hasil penelitian menunjukkan bahwa pengendalian internal pada siklus pendapatan pada PT. “X” Surabaya sudah cukup baik namun perlu ditingkatkan agar tidak terjadi penggelapan atau lapping sedangkan pada aktivitas dan prosedur pengendalian perusahaan masih adanya rangkap fungsi antar divisi yang mengakibatkan pengendalian internal pada struktur organisasi terkesan tidak fleksibel. Penilaian dan penetapan risiko sudah cukup efektif karena perusahan telah mampu menilai perumusan tujuan perusahaan secara keseluruhan yang kemudian dilakukan identifikasi risiko. Pemantauan dilakukan secara rutin oleh General Affair apabila terdapat temuan akan segera ditindak lanjuti

HUBUNGAN ANTARA IKLIM ORGANISASI DENGAN SUBJECTIVE WELL-BEING PADA KARYAWAN DI PERUSAHAAN X

Subjective well being (SWB) is one of important thing in human’s life because it may correlate with higher productivity and a good social relationship. SWB is individual’s evaluation of their experience for the whole picture or each domain of life including their satisfaction and feeling. For adult, work domain take most of the time each day. That is why situation at work might affect their evaluation. Evaluation at working situation called organizational climate. The aim of this paper is to investigate the correlation between organizational climate and subjective well being among employees. This study utilized quantitative approach with correlational design. Total number of the subject was 63 employees from X company who were selected using  population cluster sampling technique. Data collection tool was adapted from LSOCQ, SWLS and SPANE. Result showed that there was a positive correlation between organizational climate and subjective well-being among X company’s employees (r = 0.623, p = 0.000; r = 0.434, p = 0.000). Finding showed that employee who work in a good organization climate have a good subjective well-being. Finding also show that gender, age, income, status and education were believed to have a correlation with SWB on employees. Abstrak: Subjective well being (SWB) adalah hal penting yang ingin dicapai dalam kehidupan karena dapat meningkatkan produktivitas dan hubungan sosial yang baik. SWB merupakan evaluasi kepuasan dan afeksi individu terhadap pengalaman hidup mereka baik secara keseluruhan maupun per domain kehidupan. Domain yang memakan waktu paling banyak dalam kehidupan manusia dewasa adalah domain kerja. Evaluasi individu terhadap domain pekerjaannya disebut iklim organisasi. Oleh karena itu diduga bahwa iklim organisasi dapat mempengaruhi tingkat SWB karyawan. Tujuan dari penelitian ini adalah mengetahui hubungan antara iklim organisasi dengan SWB karyawan. Penelitian menggunakan pendekatan kuantitatif dengan desain korelasian. Subjek terdiri dari 63 karyawan perusahaan X dan dipilih menggunakan cluster sampling. Alat ukur iklim organisasi menggunakan LSOCQ sementara SWB menggunakan SWLS dan SPANE. Hasil menunjukan ada korelasi positif antara iklim organisasi dengan SWB (r = 0.623, p = 0.000 ; r = 0.434, p= 0.000). semakin baik iklim di suatu organisasi maka semakin tinggi SWB karyawan dan begitu sebaliknya