The present study discusses a method to estimate the elasto-plastic buckling loads for single layer reticular domes on circular plan. First, the buckled element of a reticular dome is determined by a distribution pattern of the strain energy which is calculated through eigen-value analysis. Then normalized slenderness ratio of the element is derived considering the axial force at elastic buckling load. The axial stress of the element at elasto-plastic buckling load is expressed as a function in terms of the normalized slenderness ratio. From the result, it is confirmed that the proposed procedure is effective for design of reticular domes.
The present study investigates the dynamic response of single layer latticed domes subjected to self-weight and horizontal seismic forces. A model for analysis is a hemispherical latticed dome of 60 m-span. Firstly, linear dynamic response analysis was performed to calculate the story shear coefficient C_i of the dome. And, we showed C_i distribution could be estimated from normalized response spectra. Secondly, static buckling analysis was applied to investigate buckling property of a unit truss which would represent the foundamental behaviour of the dome subjected to horizontally repeated forces. Thirdly, the elasto-plastic buckling load of the dome under self-weight and static horizontal seismic force was examined by elasto-plastic buckling analysis. In this analysis, C_i value was utilized for the equivalent static horizontal force. These results revealed that the static buckling load might be approximated in a reasonable preciseness by combined use of generalized slenderness ratio and a linear buckling analysis. Lastly, the static buckling load was compared with its dynamic buckling load, considering both geometry and material nonlinearities.
In order to evaluate our developing 3D directional borehole radar system, ReflexTracker®, we carried out experimental studies on its capability to detect foundation piles in poor subsoil in the Tokyo area, and cavities beside a housing complex in Aichi Prefecture, central Japan. To evaluate foundation pile detectability, we took omnidirectional and directional borehole radar measurements in two boreholes (vertical and tilted at 60 degrees) near known concrete piles. We utilized existing drawings and specifications that well described the piles at the site in terms of their materials, structures, locations, and depths, and conducted GPR and vertical differential magnetic surveys to confirm the exact locations of the pile heads. The measurements were successfully taken for both boreholes. The estimated 3D locations of the reflected points were in good agreement with the known pile locations, with an accuracy of 0.14 to 0.20 m from the pile for measurements with the vertical and the titled boreholes, respectively. For the cavity detectability evaluation, we collected core samples to check geological conditions and existing cavities estimated by drilling operations and N-values by SPT. The directional borehole radar measurements showed several significant reflected phases in a radargram and revealed the existence of the cavities corresponding to the drilling results obtained from 3D reflected points. As a result of the two experimental studies for foundation piles and cavity detectability of the ReflexTracker, we concluded that the system could be applied to civil engineering issues in poor subsoil ground.
The present paper discusses buckling strength of elliptic paraboloidal reticular roofs under a uniform load on a rectangular plan. The roofs are assumed as three way single layers with a pin-support at all peripheries on a rectangular plan. The buckling analyses are performed for linear buckling, elastic buckling and elastic-plastic buckling. The results of buckling loads are formulated based on two procedures for practical design use. One is an explicit but approximate formula for elastic buckling loads using a knock down factor and the other one is an implicit expression for buckling loads interpreted into a column buckling strength in terms of generalized slenderness ratio.
: Introduction Testing of Joints Laboratory Experiment on a Four Spanned Dome Buckling Behaviour of Single-Layer Latticed Domes Buckling Behaviour of Folded Plate-Like Reticular Arches Estimation Method for the Ultimate Strength of Latticed Domes and Arches Conclusion
The present paper presents an effective evaluation method for elasto-plastic buckling loads of elliptic paraboloidal lattice domes for roof on a rectangular plan. The roofs are assumed as three way of single layer with a pin-support or a simple-support at all peripheries on a rectangular plan. The buckling loads are evaluated using a simple procedure adopting a linear buckling analysis, a knockdown factor for imperfection sensitivity, and column buckling strength for axial forces in terms of a generalized slenderness proposed in ordinary recommendations.
The purpose of the present paper is to investigate an estimation procedure of the ultimate strength of reticular domes with geometrical imperfections and under non-uniform loading. The elastic plastic buckling stress has been summarized to evaluate the buckling load as a function of a normalized slenderness ratio with reduction factor α. According to several numerical comparisons, the effects of the imperfection are considerable in case of pin supported dome more than roller supported one. Even though these effects can not be neglected, the proposed procedure is proved to give a beneficial estimation of the buckling load with reduction factor α.
