New Factor to Characterize Mechanism of “Strong Column-Weak Beam” of RC Frame Structures

Most reinforced concrete(RC)frame structures did not achieve the "strong column-weak beam" failure mode in recent big earthquakes, resulting in a large number of casualties and significant property loss. To deal with this serious problem, a new column-beam relative factor was proposed to characterize the relative yield situation of column ends and beam ends. By limiting the column-beam relative factor, RC frame structures could achieve the "strong column-weak beam" failure mode under the excitation of strong ground motions. The limit values of column-beam relative factor were calculated, analyzed and verified by using structural simulation models for corner columns in the bottom story of structures, which are destroyed most seriously in earthquakes. The results show that the limit values should be analyzed under bi-directional ground motion and with different axial compression ratios of columns. The peak ground acceleration(PGA)of ground motions has no significant effect on the limit values, while the type of strong ground motions has a significant effect on the limit values.

Strong Structural Controllability Based on Leader-Follower Framework

In this paper,the strong structural controllability of the leader-follower framework is discussed.Firstly,the authors analyze different edge augmentation methods to preserve the strong structural controllability of the path-bud topology.The following four cases are considered:Adding edges from the path to the bud;adding edges from the bud to the path;adding the reverse or forward edges to the path or bud;and adding both the reverse and forward edges to the path or bud.Then sufficient conditions are derived for the strong structural controllability of the new topologies which are generated by adding different edges.In addition,it is proved that rank[A B]=n is a necessary condition for the strong structural controllability.Finally,three examples are given to verify the effectiveness of the main results.

Leader Selection for Strong Structural Controllability of Single-Integrator Multi-Agent Systems

This paper addresses the leader selection problem for strong structural controllability(SSC)of multi-agent systems(MASs). For a path-bud graph, it is proved that only one leader is required to guarantee the SSC of MASs. For a special type of topologies, based on the partition of the topology into disjoint pathes and path-buds, it is proved that the MASs is strongly structurally controllable if the root nodes of the pathes are selected as leaders. For general topologies, an algorithm is provided to determine the agents that can behave as leaders. For some special topologies, the minimum number of leaders guaranteeing the robust strong structural controllability(RSSC) of MASs is also obtained.Two examples are given to verify the effectiveness of the results.