In this paper we prove that tile set of Riemannian manifolds with parallel Ricci curvature, lower bounds for sectional curvature and injectivity radius and a upper bound for volume is coo compact in Gromov-Hausdroff t...In this paper we prove that tile set of Riemannian manifolds with parallel Ricci curvature, lower bounds for sectional curvature and injectivity radius and a upper bound for volume is coo compact in Gromov-Hausdroff topology. As an application we also prove a pinching result which states that a Ricci flat manifold is flat under certain conditions.展开更多
A flexible supporting structure that reduces seismic response of an arch is proposed. Topology and cross-sectional areas of the supporting structure modeled as a truss structure are optimized through two steps of stat...A flexible supporting structure that reduces seismic response of an arch is proposed. Topology and cross-sectional areas of the supporting structure modeled as a truss structure are optimized through two steps of static and dynamic optimization problems. In the first step, a flexible supporting structure that has diagonal displacement at the top under horizontal load is obtained by solving static optimization problems. Then, in the second step, the cross-sectional area of the flexible member is optimized to minimize the seismic response acceleration of the arch evaluated by the complete quadratic combination(CQC) method. Time-history seismic response analysis is carried out to show that the response in the normal direction of the roof successfully decreases due to flexibility of the supporting structure; in addition, installing passive energy dissipation devices into the flexible supporting structure is very effective in reducing the tangential response of the arch.展开更多
基金Supported by National Natural Science Foundation of China (19971081)
文摘In this paper we prove that tile set of Riemannian manifolds with parallel Ricci curvature, lower bounds for sectional curvature and injectivity radius and a upper bound for volume is coo compact in Gromov-Hausdroff topology. As an application we also prove a pinching result which states that a Ricci flat manifold is flat under certain conditions.
文摘A flexible supporting structure that reduces seismic response of an arch is proposed. Topology and cross-sectional areas of the supporting structure modeled as a truss structure are optimized through two steps of static and dynamic optimization problems. In the first step, a flexible supporting structure that has diagonal displacement at the top under horizontal load is obtained by solving static optimization problems. Then, in the second step, the cross-sectional area of the flexible member is optimized to minimize the seismic response acceleration of the arch evaluated by the complete quadratic combination(CQC) method. Time-history seismic response analysis is carried out to show that the response in the normal direction of the roof successfully decreases due to flexibility of the supporting structure; in addition, installing passive energy dissipation devices into the flexible supporting structure is very effective in reducing the tangential response of the arch.
