Seismic Performance Assessment of Steel Frames with Shape Memory Alloy Connections. Part I — Analysis and Seismic Demands

This article is the first of two companion articles that evaluate the seismic performance of steel moment-resisting frames with innovative beam-to-column connections that incorporate shape memory alloys (SMAs) to dissipate energy and provide recentering effectively during large earthquakes. Two types of SMA elements are considered: (1) superelastic SMA elements with recentering capability and (2) martensitic SMA elements with high energy dissipation capacity. This article describes the fundamental engineering characteristics of these SMA connections, their modeling in connections for nonlinear dynamic finite element analysis of building frames, and the validation of these connection models using data from full-scale experimental tests that were performed in previous research at Georgia Institute of Technology. Using three- and nine-story partially restrained (PR) moment frames selected as case studies from the SAC Phase II Project, nonlinear time history analyses of frames with and without SMA connections were conducted using suites of ground acceleration records. The beneficial effects of SMA connections on peak and residual deformation demands are quantified and discussed.     

New maps

Yu KUNG, the earliest geographical work, is Chinese ; modern geography in China may be considered to have begun after the Revolution of 1911. The progress of geography during the following twenty years was reviewed by Professor Chi‐Yun Chang in the Journal of the Geographical Society of China (1935, 1936). The present survey¹ of Chinese contributions to geography since 1935 is, roughly, a sequel, though the approach is not quite the same. For convenience, the paper is divided into two parts : the first, accompanied by 48 references, dealing with physical aspects, and the second, referring to 53 publications, with human aspects. A much longer paper, in Chinese, with the same title has been contributed by the author to the above‐mentioned periodical. Assistance by C. Y. Wu, H. C. Kuo, and G. C. Dunn is gratefully acknowledged.     

Early Cambrian endolithic algae

Phosphate fillings of the tunnels made by endolithic micro-organisms in the shells of Early Cambrian molluscs have been observed on phosphatic internal moulds at several sites. The best preserved examples are from the shells of the gastropod Yuwenia bentleyi from the Parara Limestone of South Australia. Three distinct types of borings are found in these shells: long unbranched tunnels that are either about 10 µm or 3 µm in diameter, and short vertical holes. The nature and distribution of the borings suggest that they were made by photosynthetic algae rather than fungi.