On the accuracy of the numerical integrals of the newmark’s method for computing inelastic seismic response

The paper proposes an algorithm of the numerical integration with the modal analysis for computing inelastic seismic responses, and furthermore, the accuracy of the numerical integration with the Newmark’s =1/4 method that is most popular in the earthquake engineering is discussed by comparing with the response computed by the proposed method

Shape analysis for inflatable structures with water pressure by the simultaneous control

Simultaneous control is an incremental technique that can be applied to shape analysis with soap film elements, when the shape has large volume and high rise. Furthermore, the tangent stiffness method is a clear and strict analytical theory to be able to solve the problems with large deformational behavior. The simultaneous control brings out the best performance for form-finding of isotonic surfaces in combination with the tangent stiffness method. This study proposes a significant modification of the simultaneous control. The modification realizes a wide application range regarding load conditions and boundary conditions for soap film shape analyses by calculating the average of surface tension. Results are presented as some computational examples in which the behavior of soap film structures under air pressure and /or water pressure becomes evident

An accurate algorithm of numerical integration for computing seismic responses of inelastic structures

The paper proposes an algorithm that makes numerical integrations with conditions for stability to be usable for computing inelastic seismic responses of structures. The numerical integrations with conditions cannot be applied to solving directly the equation of the motion. These numerical integrations, however, give exacter results in linear seismic responses than that by the numerical integrations without any conditions. The method of modal analysis can clear the condition by applying the eigenvalue analysis to the equation of the motion expressed by the tangent stiffness in the inelasticity. The paper shows considerable difference between the result by the numerical integration with conditions and that without any condition, and the former result will be exacter than the latter from several proofs in the discussion

Mechanically rational forms of curved surface structures shaped from the uniform strain elements

The paper proposes a method for finding mechanically rational and practical forms of curved surface by using the uniform strain elements. Numerical methods for form finding already published give exact solutions but the application is restricted to the problems with the conditions possible to form a minimal surface. This is because the methods use the mechanical model without material stiffness but with only the geometric stiffness of isotropic tension. When the uniform strain elements composing a structural form have even isotropic strain in all over the form, the form is an isotropic tension form. Since the uniform strain element has the material stiffness, the method can stably yield a form with the strains varying as narrowly as possible in the curved surface under the condition impossible to shape a minimal surface

Form-finding of extensive tensegrity using truss elements and axial force lines

Tensegrity structure, which consists of cables and struts, are expected to be used as systems for cosmological, foldable and/or inflatable structures. The equilibrium shape of the tensegrity can be determined by iteration of solving the tangent stiffness equation. Here, it is rational to use the truss elements for struts and the axial force line elements for cables. In this study, a way to find the shapes of "extensive tensegrity", which counts their self-weight and permits support conditions of statically indeterminate. As results of numerical examples, even the case where many solutions exist under the same loading conditions like the tower tensegrity, expected one equilibrium solution can be obtained, and its equilibrium path can be drawn

An orthotropic membrane model replaced with line-members and the large deformation analysis

The paper proposes a method for analyzing large deformation of membrane structures by replacing the structures with elements composed line-members. The replacement has the advantage that the structural model is completely compression-free, so that the analysis always has a unique equilibrium solution without falling into multi equilibrium problems and the method is stable and easy even for how large deformation

Shape analysis for inflatable structures with water pressure by the simultaneous control

Simultaneous control is an incremental technique that can be applied to shape analysis with soap film elements, when the shape has large volume and high rise. Furthermore, the tangent stiffness method is a clear and strict analytical theory to be able to solve the problems with large deformational behavior. The simultaneous control brings out the best performance for form-finding of isotonic surfaces in combination with the tangent stiffness method. This study proposes a significant modification of the simultaneous control. The modification realizes a wide application range regarding load conditions and boundary conditions for soap film shape analyses by calculating the average of surface tension. Results are presented as some computational examples in which the behavior of soap film structures under air pressure and /or water pressure becomes evident

An Orthotropic Membrane Model for the Large Deformation Analysis and Snapping Phenomena of the Dome Inflated

The paper proposes a method to enable analyzing any large deformation of membrane structures. If the analysis uses even very small rigidity against compression in the structures, the computation becomes multi-bifurcated problem and unstable. The original compression-free model used in the method keeps the structures in tension field and this makes computing the deformation always very stable. The paper uses the advantage of the method and shows a snapping phenomenon during constructing a membrane dome. Though the snapping phenomenon is not so public, the phenomenon occasionally happens in the construction site and it causes the destruction

On the accuracy of the numerical integrals of the newmark’s method for computing inelastic seismic response

The paper proposes an algorithm of the numerical integration with the modal analysis for computing inelastic seismic responses, and furthermore, the accuracy of the numerical integration with the Newmark’s  =1/4 method that is most popular in the earthquake engineering is discussed by comparing with the response computed by the proposed method