Towards the “ultimate earthquake-proof” building: Development of an integrated low-damage system

The 2010–2011 Canterbury earthquake sequence has highlighted the severe mismatch between societal expectations over the reality of seismic performance of modern buildings. A paradigm shift in performance-based design criteria and objectives towards damage-control or low-damage design philosophy and technologies is urgently required. The increased awareness by the general public, tenants, building owners, territorial authorities as well as (re)insurers, of the severe socio-economic impacts of moderate-strong earthquakes in terms of damage/dollars/ downtime, has indeed stimulated and facilitated the wider acceptance and implementation of cost-efficient damage-control (or low-damage) technologies. The ‘bar’ has been raised significantly with the request to fast-track the development of what the wider general public would hope, and somehow expect, to live in, i.e. an “earthquake-proof” building system, capable of sustaining the shaking of a severe earthquake basically unscathed. The paper provides an overview of recent advances through extensive research, carried out at the University of Canterbury in the past decade towards the development of a low-damage building system as a whole, within an integrated performance-based framework, including the skeleton of the superstructure, the non-structural components and the interaction with the soil/foundation system. Examples of real on site-applications of such technology in New Zealand, using concrete, timber (engineered wood), steel or a combination of these materials, and featuring some of the latest innovative technical solutions developed in the laboratory are presented as examples of successful transfer of performance-based seismic design approach and advanced technology from theory to practice

Effect of responsive classroom approach on caring and respectful behaviors of children

Responsive Classroom (RC) approach to teaching is a specific type of character education program that incorporates a social curriculum. While many character education programs are “tagged onto” traditional academic curricula, RC places equal emphasis on enhancing social skills and enhancing academic skills. Responsive Classroom approach aims to teach children important values such as treating others with respect and care, taking responsibility for one’s own actions, and self-control. With high percentages of divorce and broken homes, crime rates on the rise, bullying, school shootings, and other social catastrophes taking place daily, proponents of the RC approach suggests that RC curricula offers teachers and administrators the opportunity to impact young lives by embracing the role of social educator. This study aimed to describe and better understand the Responsive Classroom approach at a public elementary school in Connecticut. The overarching question that guided the research was: Does the RC approach promote caring and respectful behaviors among children? Through interviews, observations, and document analysis findings suggest that the social skills of children at that particular school exemplified caring and respectful behaviors. Implications of this study propose that the Responsive Classroom approach has a positive impact on the social skills and behaviors of students in RC schools

Time-resolved PhotoEmission Spectroscopy on a Metal/Ferroelectric Heterostructure

In thin film ferroelectric capacitor the chemical and electronic structure of the electrode/FE interface can play a crucial role in determining the kinetics of polarization switching. We investigate the electronic structure of a Pt/BaTiO3/SrTiO3:Nb capacitor using time-resolved photoemission spectroscopy. The chemical, electronic and depth sensitivity of core level photoemission is used to probe the transient response of different parts of the upper electrode/ferroelectric interface to voltage pulse induced polarization reversal. The linear response of the electronic structure agrees quantitatively with a simple RC circuit model. The non-linear response due to the polarization switch is demonstrated by the time-resolved response of the characteristic core levels of the electrode and the ferroelectric. Adjustment of the RC circuit model allows a first estimation of the Pt/BTO interface capacitance. The experiment shows the interface capacitance is at least 100 times higher than the bulk capacitance of the BTO film, in qualitative agreement with theoretical predictions from the literature.Comment: 7 pages, 10 figures. Submitted to Phys. Rev.

Performance of Flexure-Controlled Reinforced Concrete Structural Walls Under Sequential Fire-Earthquake Loads

The performance of reinforced concrete (RC) structural walls under individual hazards has been well studied. However, little is known regarding the behavior of RC structural walls under sequential hazards. The research presented here seeks to address the performance of RC structural walls under sequential fire-earthquake loads (both post-earthquake fire and post-fire earthquake). Longer burn times of post-earthquake fire and initial seismic damage can have significant structural impacts on RC structures which are usually considered to have superior performance in a fire. An 8-inch wall with characteristics representative of typical construction in seismic regions was utilized as the basis of the simulations. The wall with non-uniform layout of reinforcement provides a complex deformed shape under fire. Individual typical earthquake damage states were introduced to the wall to assess impact on fire resistance. The fire resistance of a wall was discussed according to thermal-insulation and load-bearing criteria in codes. The results show that crack does not impact the fundamental response of a wall under fire while cover loss decreases its load-bearing capacity significantly. Moreover, the location of cover loss has remarkable impact on the deformed shape of a wall and its load-bearing fire resistance. While the thermal-insulation capacity decreases below code requirements, the load-bearing fire resistance of earthquake-damaged walls is still acceptable. Another potential but infrequently studied hazard is the post-fire earthquake scenario. The impact of fire damage on the earthquake behavior of RC walls is not well understood, which leads to some safety concerns in earthquake after fire or aftershocks after post-earthquake fire. A simulation procedure combining SAFIR and OpenSees is proposed and validated for the PFE analysis of RC structural walls. Based on the validated the simulation procedure, a parametric study on the PFE performance of RC walls was conducted. Results indicate that fire damage decreases the load-bearing capacity and stiffness of RC walls under reversed-cyclic loads while fire damage decreases the deformation capacity in most cases. Severe fire exposure may shift damage from the boundary element to the web. Wall characteristics which significantly impact the residual wall response quantities are wall thickness, boundary element length, and axial load ratio. In addition, a framework for simplified nonlinear modeling was proposed for the PFE performance of RC walls. The models are defined by modification factors that account for the change in wall response relative to that of a wall without fire damage. Modification factors, established from the results of the parametric study, are a function of fire damage indices that account for the effect of fire on the material properties of steel and concrete. Results indicate that the model is generally able to predict the response of a fire-damaged wall

Pin-supported walls as seismic retrofit for existing RC frames: performance improvement through link removal

Pin-supported (PS) walls represent a possible solution for the seismic retrofit of existing reinforced concrete (RC) buildings, enabling linearization of the frame deformation along its height and consequently inhibiting soft storey collapse mechanisms. The effectiveness of this rehabilitation technology is strongly related to the characteristics of the existing frames, especially to the vertical distribution of the frame storey lateral stiffness. Since a larger 1st storey lateral stiffness may lead to a detrimental structural response of the retro- fitted system, an alternative solution obtained from removing the connecting link between the 1st floor of the existing building and the pin-supported wall is investigated in this paper. An analytical method is proposed to derive the distribution of the internal actions in a dual 2D RC frame-PS wall system without the link at the 1st floor level, considering both a lin- ear and nonlinear behaviour of the frame. It emerges that some parameters describing the structure type can provide straightforward information on the suitability of this solution in the seismic retrofit of existing RC buildings. As a result, a simplified procedure has been derived to preliminarily define the retrofit system configuration and evaluate the maximum demand in the PS wall. Such a procedure is finally applied with reference to a frame rep- resenting a RC building and finite element model analyses are carried out for validation purposes

Organic Rankine cycle receiver development

The selected receiver concept is a direct-heated, once-through, monotube boiler operated at supercritical pressure. The cavity is formed by a cylindrical copper shell and backwall, with stainless steel tubing brazed to the outside surface. This core is surrounded by lightweight refractory insulation, load-bearing struts, and an outer case. The aperture plate is made of copper to provide long life by conduction and reradiation of heat away from the aperture lip. The receiver thermal efficiency is estimated to be 97 percent at rated conditions (energy transferred to toluene divided by energy incident on aperture opening). Development of the core manufacturing and corrosion protection methods is complete

Seismic-proof buildings in developing countries

The use of \u201cductile seismic frames,\u201d whose proper seismic behavior largely depends upon construction details and specific design rules, may do not always lead to effective seismic resistant structures, as dramatically denounced by the famous Chinese artist Ai Weiwei in his artwork Straight. The artwork (96 t of undulating metal bars that were salvaged from schools destroyed by the 2008 Sichuan, China earthquake, where over 5,000 students were killed) is a clear denounce against the corruption yielding to shoddy construction methods. The issue of safe constructions against natural hazards appears even more important in developing countries where, in most cases, building structures are realized by non-expert workers, or even by simple \u201cpeople from the street,\u201d who does not have any technical knowledge on construction techniques and seismic engineering. In this paper, a brief history from the first frame structures to the more efficient wall-based structures is provided within Earthquake Engineering perspectives. The superior structural properties of box-type wall structures with respect to conventional frame structures envisage a change of paradigm from actual \u201cductility-based\u201d Earthquake Engineering (centered on frame structures) toward 100% safe buildings through a \u201cstrength-based\u201d design exploiting the use of box-type wall-based structures

The use of data-mining for the automatic formation of tactics

This paper discusses the usse of data-mining for the automatic formation of tactics. It was presented at the Workshop on Computer-Supported Mathematical Theory Development held at IJCAR in 2004. The aim of this project is to evaluate the applicability of data-mining techniques to the automatic formation of tactics from large corpuses of proofs. We data-mine information from large proof corpuses to find commonly occurring patterns. These patterns are then evolved into tactics using genetic programming techniques