A proper composition of stiffness and ductility parameters is required to obtain a resistant and economic structure. Accordingly, Chevron Knee Braced Frame (CKBF) seems appropriate due to its proper seismic performance. The advantage of this system comes to having the capability of rapid and cheap replacement of chevron knee elements after an earthquake occurs. In this research, response modifi...

In this article, after a brief description of some signi®cant catastrophic structural failures going back to the period when iron and steel began to replace wood and masonry as the primary structural materials, the historical development of the ®eld of fracture mechanics is discussed. First, the basic concepts of the ®eld, the motivation underlying their development and the key contributions ma...

The decline and loss of species is inevitable in the face of growing human pressures on the environment but, according to one group of senior researchers, a standard framework is needed to assess the rate of this decline if researchers wish to be effective and policymakers are to take note.