Papers by Nathan Madutujuh
The availability of advanced high strength material and structural system have made much thinner ... more The availability of advanced high strength material and structural system have made much thinner and more flexible structures feasible. These slender structures usually require the use of nonlinear analysis, with materially nonlinear or geometrically nonlinear effects, especially in high seismic area. The use of existing nonlinear analysis procedures are time consuming, more difficult to implement and in most methods, can not go beyond limit points. To cope with these problems, a new nonlinear analysis procedure, that is more stable, simpler and faster, called Direct Nonlinear Analysis using a Method, has been developed. The new procedure has been tested for single and multidimensional problems with good results. The method can be extended to various problems, and can be improved to make it even faster or more stable using several interpolation/extrapolation methods. The availability of this new method will open new field of research in nonlinear analysis to provide us with better nonlinear analysis solution.
To achieve an optimized design of beams and columns, sometimes a tapered, curved element, honeyco... more To achieve an optimized design of beams and columns, sometimes a tapered, curved element, honeycomb or truss beam will be used in the structural model. In recent development of aseismic steel structure, a reduced flange beam is used to control the location of energy dissipation. This approach will require development of new frame element stiffness matrix that due to its complexity may not have explicit equation available. In this paper, a general approach to derive a new stiffness matrix of 3D frame element with any longitudinal shape, void pattern and shear deformation will be given using Flexibility approach. Stiffness matrix derived from flexibility matrix using Symbolic math and Gauss Quadrature Numerical Integration are also given. Sample problems also given to verify the resulted stiffness matrix. Using this procedure, a new stiffness matrix can be derived for any section with any shape of tapered element.
In this paper we will study the effects of horizontal and vertical earthquake acceleration on the... more In this paper we will study the effects of horizontal and vertical earthquake acceleration on the water surface angle of Roof-top swimming pool on top of medium and tall buildings. In this study we will assume simplified condition of constant acceleration and neglect the effects of the shape of the pool. Simple formula for relation between water surface angle and earthquake acceleration will be derived and used for parametric study for Indonesian earthquake zone. To get the peak acceleration on roof top, a simplified equation derived from continuum system will be derived. The equation can be used to find the magnification factor that can be used to compute peak acceleration on
roof top. From the parametric study, it is found that there is a great risk for water spill out for roof-top swimming pool, especially for medium rise building at medium risk earthquake zone. A simple design procedure is given following the discussion.
Jurnal Teknik Sipil, Jun 25, 2012
A blast resistant single door was designed to withstand a 0.91 bar blast pressure and 44 ms blast... more A blast resistant single door was designed to withstand a 0.91 bar blast pressure and 44 ms blast duration. The analysis was done using Dynamic Time History Analysis using Blast Load modeled as Impact Load for given duration. The material properties used have been modified to accommodate dynamic effects. The analysis was done using dynamic finite element method (fem) for time of the blast duration, and the maximum/minimum internal forces and displacement were taken from the time history output, in order to know the behavior under blast load and estimate the safety margin of the door. Results obtained from this research indicated that the maximum z-displacement is 1.709 mm, while in the term of serviceability, the permitted is 25 mm. The maximum reaction force is 73,960 N, while the maximum anchor capacity is 82,069 N. On blast condition, the maximum frame stress is 71.71 MPa, the maximum hinge shear stress is 45.28 MPa. While on rebound condition, the maximum frame stress is 172.11 MPa, the maximum hinge shear stress is 29.46 MPa. The maximum door edge rotation is 0.44 degree, which is not exceed the permitted boundary (1.2 degree).
Drafts by Nathan Madutujuh
SANSPRO is an integrated software designed for 3D modelling, analysis, steel/concrete design, con... more SANSPRO is an integrated software designed for 3D modelling, analysis, steel/concrete design, concrete capacity design, foundation design, detail drawing generator, volume and cost computation, and report generator.
The wide availability of high strength cold-formed steel profile enable engineers to use it for s... more The wide availability of high strength cold-formed steel profile enable engineers to use it for structural purpose. Due to its low strength to weight ratio, the building with cold-formed steel profiles is suitable for region with high seismic activity. Application of such thin and small section profile requires truss assembly for column and beams, requiring more efforts in modeling and resulting in large degree of freedom model. An interactive parametric-based layout oriented approach has been developed to model a cold-formed steel building easily. Using this approach, it is easier to include bracings and window/doors openings.
Analyzing a large 3D model of a high rise building usually needs large amount of time and computi... more Analyzing a large 3D model of a high rise building usually needs large amount of time and computing power. The model can be reduced to half size by introducing the rigid floor diaphragm and applying in-plane constraints to slave nodes so that they will rotate in accordance with master node. The total number of DOF will be reduced from NF x NJ x 6 to become NF x 3 + NF x NJ x 3, almost half of the total DOF. Because the solver algorithm processing time is about N^2.5 related to the number of DOF N, the time needed will be reduced to about 20-25% of the original time needed. There are several method for finding the reduced matrix from the original matrix, the original one is involving the well known Static Condensation techniques, requiring multiplication and inverse of several submatrices. In this paper, a new simple and straightforward method will be introduced, using the available linear solver to get the much smaller matrix, and then using the simple Cholesky Factorization to get the reduced stiffness matrix. The method has been applied to SANSPRO integrated structural analysis and design program for static and dynamic analysis with good results.
A multistory or tall building is usually constructed floor by floor with a construction cycle typ... more A multistory or tall building is usually constructed floor by floor with a construction cycle typically is from 7 to 14 days. Modeling such buildings as a whole final structure will give different results than actual condition, because in real condition, the self-weight and dead load of the building is added sequentially on a floor at a time. This effect will be more significant for building with transfer beam and building with diagonal bracing. Furthermore, during the construction stages, the concrete strength also increasing from its initial value fci to its full value fc', adding more displacement compared to analysis with constant fc'. In this paper a simple and straightforward method will be used to solve these problems.
Analyzing a large 3D model of a high rise building usually needs large amount of time and computi... more Analyzing a large 3D model of a high rise building usually needs large amount of time and computing power. The model can be reduced to half size by introducing the rigid floor diaphragm and applying in-plane constraints to slave nodes so that they will rotate in accordance with master node. The total number of DOF will be reduced from NF x NJ x 6 to become NF x 3 + NF x NJ x 3, almost half of the total DOF. Because the solver algorithm processing time is about N^2.5 related to the number of DOF N, the time needed will be reduced to about 20-25% of the original time needed. There are several method for finding the reduced matrix from the original matrix, the original one is involving the well known Static Condensation techniques, requiring multiplication and inverse of several submatrices. In this paper, a new simple and straightforward method will be introduced, using the available linear solver to get the much smaller matrix, and then using the simple Cholesky Factorization to get the reduced stiffness matrix. The method has been applied to SANSPRO integrated structural analysis and design program for static and dynamic analysis with good results.
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Papers by Nathan Madutujuh
roof top. From the parametric study, it is found that there is a great risk for water spill out for roof-top swimming pool, especially for medium rise building at medium risk earthquake zone. A simple design procedure is given following the discussion.
Drafts by Nathan Madutujuh
roof top. From the parametric study, it is found that there is a great risk for water spill out for roof-top swimming pool, especially for medium rise building at medium risk earthquake zone. A simple design procedure is given following the discussion.