Distributed Tuned Mass Dampers for Multi-Mode Control of Benchmark Building under Seismic Excitations

The effectiveness of the multi-mode control of seismically excited building installed with distributed multiple tuned mass dampers (d-MTMDs) is investigated by comparing dynamic response with the other controllers, such as passive friction dampers, semi-active dampers, single tuned mass damper (STMD), and multiple tuned mass dampers (MTMDs-all.top), both installed at the top of the building, and arbitrarily distributed MTMDs (ad-MTMDs). It is concluded that the d-MTMDs exhibit improved performance as compared with the STMD, MTMDs-all.top, and ad-MTMDs. The d-MTMDs are also convenient to install owing to the reduced space requirements, being placed at various floors.     

Policy capacity in disruptive times

ABSTRACT

In considering the widely held view that we have experienced an era of qualitative decline in policy provision, this paper briefly reviews four questions that appear to underlie such a view. Have there been identifiable transitions in deliberative processes, political practices and policy capacity in recent decades (and if so, what were the catalysts)? Has the relationship between policy practitioners and expert providers of policy advice changed (and if so, how)? Have channels of communication between the political/policy community and the research community deteriorated (and if so, why)? Has the political appreciation of public concerns and the public understanding of policy imperatives diminished? We use these to frame the results of a workshop in which researchers, policy practitioners and service providers participated. Our objective is to identify systematically the origin of contemporary policy problems, foreshadowing four articles that illuminate instances of success and failure in disruptive times.     

Assessment Techniques for Studying the Effects of Fire on Stone Materials: A Literature Review

ABSTRACT

Fire is one of the most severe threats to stone applied in civil engineering and architecture. In most cases, its effects are irreversible and have long-lasting repercussions. In addition to aesthetic alterations, fire can also induce important mineral-chemical, physical, and mechanical changes in stone. Research concerning the effects of fire on stone materials in recent decades has been providing valuable knowledge to inform present and future conservation and restoration actions. In this literature review, the properties and techniques used for studying the effects of fire on stone materials are appraised, summarized, and compiled. A comprehensive and practical overview of those effects is also given. Open porosity and P-wave ultrasonic velocity are the physical and mechanical properties that have been studied most. Other frequently researched areas include chemical-mineralogical changes, color, density, water absorption, uniaxial compressive strength, and modulus of elasticity are also very frequently investigated.