Construction Technologies and Architecture Vol. 7

Abstract: An analytical method is presented for free vibration of a symmetrically laminated rectangular plate with point masses, and experimental modal analysis is conducted to compare both sets of the frequency data. The problem is solved by an extending Ritz method to include kinetic energy caused by added point masses under any sets of edge conditions, and a frequency equation is derived by minimizing the energy functional. In numerical computation, the accuracy of the solution is studied by convergence test and comparison with the existing result in the specific case. Then, the experimental modal analysis is applied to measure the natural frequencies and mode shapes. The two sets of results are compared, and the validity of both theoretical and experimental approaches is established.

Abstract: This paper describes an approach extended from Ritz method to analyze the free vibration of thin isotropic annular plates in good accuracy, and presents comprehensive lists of natural frequencies of the plate for all possible sets of classical boundary conditions. Analytical process is developed to introduce the boundary index that allows to accommodate any sets of free, simple supported and clamped edges along inner and outer boundary of the plate. Convergence and comparison studies are made to demonstrate numerical accuracy in the frequency parameters. Results are summarized for nine sets of boundary conditions and six different ratios of (inner radius)/(outer radius), and are intended to serve for uses of design data and comparison in relevant future papers.

Abstract: Instability is one of the factors causing damage and injury that results in permanent disability. To increase the stable load-carrying capacity, a simplified and efficient computational method for determining the first critical load is necessary for the structure's structural design, application and safety. This study aims to determine the characteristics of the critical bending moment M_bcr and the critical torsion moment M_Tcr due to geometric size variations in the square, diamond, and circle cross-sectional hollow pipes so that consideration of the selection of hollow pipe size and cross-sectional shape is obtained under pure bending and pure torsion to minimize the occurrence of instability of the structure. The geometric size variation is carried out by changing the value of a/t in the quadrilateral pipe, the value of D/t in the circular pipe, and the length of the pipe L in each cross-sectional shape. This research was conducted using Finite Element Analysis-based software with linear and nonlinear buckling analyses. The moment load is given at the centre point of the model end, and the boundary conditions are set to see the deformation on the mid-span section of the pipe. The results showed that M_bcr and M_Tcr were inversely proportional to the values of a/t, D/t, and . The largest value of M_bcr belongs to the circular pipe. The value of M_bcr in the diamond pipe is greater than the square pipe but getting closer to the same as the value of L increases the M_Tcr value of both cross-sections is the same. The M_Tcr curve in the cross-section of the circle has a higher degree of steepness than the square and diamond cross-section. At the same value, the more the value of a/t and D/t increases thickness change has more compared to the circular pipe. At the same L, the greater the value of a/t and D/t, the difference in the M_bcr between the cross-section of the circle and the quadrilateral is smaller, but the difference in M_Tcr tends to be the same. At the same value of a/t and D/t, the oval deformation value and angle of twist will get bigger, but the M_bcr and M_Tcr values are getting smaller and will be constant at a given pipe length.

Abstract: In general, buildings can be classified into Engineering buildings and Non-engineering buildings. Non-engineering building is a simple building such as a residential house that does not carry out structural calculations. Non-engineering buildings are very susceptible to lateral loads such as earthquakes which can cause collapse. Therefore, research is carried out in the form of laboratory tests and numerical tests for reinforced concrete frames filled with prefabricated cellular lightweight concrete (CLC). In this study, two specimens were used, namely an empty frame and a reinforced concrete frame filled with prefabricated CLC. In the laboratory test, it was analyzed by means of a cyclic load test, while in the numerical test the first specimen was made an open frame model and the second infill wall was made as an equivalent diagonal strut. Both of these models were analyzed using the SAP 2000 application version 22 by applying pushovers. The results showed that there were differences in laboratory tests and numerical tests. Therefore, a correction value for the numerical test results is needed to approach the value of the numerical test results.

Abstract: Sandeq is a type of outrigger sailing boat used by Mandar fishermen to catch fish as well as a mode of transportation between islands. Sandeq boat has a mast made of bamboo that is called pattung. Recently, the raw material for the mast is very rare, so it is necessary to find alternative materials with equal quality and strength. In this study, numerical simulations were carried out by modeling masts made of aluminum, fiberglass and bamboo using Finite Element Method (FEM). The workload used is the maximum load of the main sail. The results showed that alternative materials that can replace bamboo are aluminum 6061 (AL 6061) and fiberglass (FRP). By applying the caseload on the Sandeq mast, it is found that the AL 6061 experiences stress with 78 MPa, and FRP experiences stress with 150 MPa. Both of these materials are suitable for use as an alternative material for the Sandeq mast with a safety factor SF ≥ 5.