Seismic Vulnerability Assessment of Modular Steel Buildings

Contemporary seismic design is based on dissipating earthquake energy through significant inelastic deformations. This study aims at developing an understanding of the inelastic behavior of braced frames of modular steel buildings (MSBs) and assessing their seismic demands and capacities. Incremental dynamic analysis is performed on typical MSB frames. The analysis accounts for their unique detailing requirements. Maximum inter-story drift and peak global roof drift were adopted as critical response parameters. The study revealed significant global seismic capacity and a satisfactory performance at design intensity levels. High concentration of inelasticity due to limited redistribution of internal forces was observed.     

THE FUTURE TRAJECTORY OF U.S. CO2 EMISSIONS: THE ROLE OF STATE VS. AGGREGATE INFORMATION*

ABSTRACT This paper provides comparisons of a variety of time‐series methods for short‐run forecasts of the main greenhouse gas, carbon dioxide, for the United States, using a recently released state‐level data set from 1960–2001. We test the out‐of‐sample performance of univariate and multivariate forecasting models by aggregating state‐level forecasts versus forecasting the aggregate directly. We find evidence that forecasting the disaggregate series and accounting for spatial effects drastically improves forecasting performance under root mean squared forecast error loss. Based on the in‐sample observations we attempt to explain the emergence of voluntary efforts by states to reduce greenhouse gas emissions. We find evidence that states with decreasing per capita emissions and a “greener” median voter are more likely to push toward voluntary cutbacks in emissions.     

The Effects of Climate and Socio‐Demographics on Direct Household Carbon Dioxide Emissions in Australia

Household CO₂ emissions are a significant contributor to global greenhouse gas emissions and consequently climate warming. Despite this, there has been little consideration of how household CO₂ emissions may be affected by changes in climate. The aim of the present study has been to investigate the way climate, as well as socio‐demographic characteristics, may affect household CO₂ emissions produced from energy use. A national online survey was conducted to determine current household CO₂ emissions in Australia as well as capture the ownership and use of household appliances and installations. Electricity and gas‐based emissions as well as the ownership of a variety of household appliances and installations were found to be strongly associated with temperature. Electricity and gas emissions were found to decrease as annual average temperatures increase. However, as temperatures continue to rise under climate change this pattern may be reversed owing to increased reliance on air conditioners. One option for preventing this from occurring is to encourage houses to adopt more solar‐passive installations. Although this may be expensive, households with higher emissions tend to have higher incomes, indicating that they may have the capacity to pay for such installations.     

The Role of Pilot Projects in Urban Climate Change Policy Innovation

Cities are taking a leadership role in addressing global climate change and reducing greenhouse gas (GHG) emissions, but policy innovations are needed to help cities move from goals to outcomes. Pilot projects are one means by which cities are experimenting with new ways of governing and financing climate change mitigation. In this paper, we develop a framework for understanding the role of pilot projects in urban policy innovation: their emergence and rationale, and the means by which they ultimately scale up and out to reduce GHG emissions. We use this framework to evaluate a pilot project for retrofitting social housing buildings in Toronto. We find the initial pilot project helped address the challenges of pursuing deep retrofits of social housing. Scaling these lessons up to the city level required overcoming challenges to financing and coordinating a larger project; scaling out to the provincial level revealed institutional and political obstacles to pursuing the co-benefits of deep building retrofits in social housing. Bridging agents play an important role in both scaling processes. The analysis reveals the additive nature of urban policy innovation and the dynamic interplay of change agents and institutional and political context in innovation processes.     

Multi‐analytical Studies of the Lime Mortars from the Yanxi Hall in the Yangxin Palace of the Palace Museum (Beijing)

For centuries, the architecture of the Palace Museum represented the highest standard of Chinese architecture. The Yangxin Palace of the Palace Museum consisted of 18 masonry buildings built using bricks, wood, roof tiles and various mortars. In 2016, a five‐year project was initiated to work on the maintenance and restoration of the Yangxin Palace buildings. The characterization of the construction materials has become of primary importance, in order to obtain information about the raw ingredients and building technology of the mortars, and the history of possible previous restorations. In this paper, 12 different samples representing three types of mortar‐based materials—namely, jointing mortars between the bricks on the wall, and surface plasters as well as mortars used on the roof—were collected for analysis from the Yanxi Hall of the Yangxin Palace. Analysis into the composition, grain‐size distribution, organic and fibre additives and testing of the mortar density and water absorption were performed. Starch, protein and plant fibres were identified in some of the samples. Brucite, mullite and ettringite were detected within most mortars on the roof, possibly originating from the furnace slag added into the raw materials for restoration purposes. The analytical results will serve as a critical reference for the maintenance and restoration of the buildings in the Yangxin Palace.     

Beyond Kyoto? Media Representation of an Environmental Issue

Human‐induced climatic change, and particularly the enhanced greenhouse effect, became significant environmental issues in the 1990s. They were given prominent coverage in the Australian media at the time of the Third Conference of the Parties to the Climate Convention (COP3) in Kyoto in 1997, when Australia obtained permission for an 8 per cent increase in its greenhouse gas emissions by 2012. Meanwhile, other major emitters of greenhouse gases were accepting targets of significantly reduced emissions. Given the controversy associated with this, it might have been expected that the Australian media's coverage of COP4 in Buenos Aires, only 11 months later, would have been extensive. This was not the case. Analysis of seven Australian newspapers shows that, with the exception of an alternative weekly newspaper, the coverage of COP4 was an example of ‘embodiment’ (the uncritical acceptance of certain assumptions and practices) and ‘distanciation’ (the separation of cause and effect in regard to an issue).     

A Simplified Drift-Based Assessment Procedure for Regular Confined Masonry Buildings in Seismic Regions

This article presents a simplified procedure for assessing the seismic performance of existing low-to-medium rise confined masonry (CM) buildings, which are a typical construction type in Latin-America. The procedure consists of the estimation of the peak roof and first-story inelastic drift demand of CM buildings. The expected peak inelastic displacement demand is related to drift-based fragility curves, which express the probability of being or exceeding two key damage states in the masonry panels, developed from a relatively large experimental database. The proposed procedure could be very useful for obtaining rapid estimates of expected performance during future earthquake events and for assessing the seismic vulnerability of regular confined masonry structures.     

The 9th century BCE destruction layer at Tell es-Safi/Gath,Israel: integrating macro- and microarchaeology

Destruction events in multi-period sites are valuable marker horizons that represent time-synchronous events across the site and sometimes between sites. Destruction layers often preserve rich finds that provide insights into site use. Here we use both macro- and microarchaeological methods to study a destruction event from the late 9th century at Tell es-Safi/Gath in Israel. A major conflagration at this specific location resulted in the consolidation of parts of the roof construction materials, thus enabling us to differentiate between roof, walls and floor materials. We could reconstruct the events which lead to the formation of an approximately 80 cm thick layer. The base of this layer that overlies the floor surface is a thin charred organic material-rich ash layer. As the clays in this layer were not altered by heat and the ceramics still have preserved residues, we conclude that the ash was produced elsewhere and was redistributed to this location. Ceramics that are associated with burnt roof sediments do not have preserved residues. We also estimate the time that each of the accumulation events might have taken, and conclude that this accumulation occurred over decades. The architecture and artifacts found within and beneath the destruction do not allow us to unequivocally identify the function of this area prior to destruction. We do however identify an unusual bin and associated stone pavement, and a corner rich in artifacts, phytoliths and charred organic material. We also show that a wall was built of fired mud bricks; a most unusual occurrence for this time period in the Levant. This study demonstrates well the usefulness of an integrated macro- and microarchaeological approach to understanding the archaeological record, as well as the benefits of using an on-site laboratory.     

Exploration of Basel Mission Company shipwreck remains at St George's Reef off Goa, West Coast of India: impact of the Basel Mission Co. on society and culture

A systematic exploration of shipwrecks has been carried out in Goa waters since 1997. Exploration off St George's Reef has brought to light the remains of a shipwreck at a depth of 15 m, containing various types of terracotta artefacts intended for house construction. Basel Mission Tile Works 1865' is impressed on bricks, roof and floor tiles. Study shows that the company was active in manufacturing terracotta and exported it to Africa, Australia, Borneo, Sumatra, and other countries. It has been renamed 'Comtrust', and is still producing terracotta using the same techniques. The impact of the Basel Mission Co. on society and culture is discussed. A study of finds of wrecks in the Mangalore and Calicut areas was undertaken.     

Green cities? Urbanization,trade, and the environment

Is urbanization good for the environment? This paper establishes a simple core–periphery model with monocentric cities, which comprises key forces that shape the structure and interrelation of cities to study the impact of the urban evolution on the environment. We focus on global warming and the potential of unfettered market forces to economize on emissions. The model parameters are chosen to match the dichotomy between average “large” and “small” cities in the urban geography of the United States, and the sectoral greenhouse gas emissions recorded for the United States. Based on numerical analyzes we find that a forced switch to a system with equally sized cities reduces total emissions. Second, any city driver which pronounces the asymmetry between the core and the periphery drives up emissions in the total city system, too, and the endogenous adjustment of the urban system accounts for the bulk of the change in emissions. Third, none of the city drivers gives rise to an urban environmental Kuznets curve according to our numerical simulations. Finally, the welfare‐maximizing allocation tends to involve dispersion of cities and the more so the higher is the marginal damage from pollution.     

Prediction of High-Damping Seismic Demands in Eastern North America

This article investigates high-damping seismic demands and associated damping reduction factors in Eastern North America (ENA). A database of hybrid empirical records with moment magnitudes M ≥ 6.0 is first studied to evaluate 5%- to 30%-damped seismic demands. A new magnitude- and distance-based equation is proposed to predict ENA spectral displacements and then used to characterize their sensitivity to variations in period, magnitude, epicentral distance and site conditions. The proposed equation is also used to assess damping reduction factors in ENA. The results contribute to improved assessment of seismic demands in ENA while accounting for added-damping in structural seismic design.     

Ambitious deep energy retrofits of buildings to accelerate the 1.5°C energy transition in Canada

Scientists advise limiting global warming to 1.5°C with substantial actions by 2030. Our viewpoint argues that climate response strategies in Canada have underemphasized and underestimated the potential contribution deep energy retrofits can make to greenhouse gas (GHG) emissions reductions, leading to inadequate responses in the building sector, and that Canada can (and should) be ambitious with building retrofits over the next decade. GHG savings from building retrofits can be realized more quickly than GHG reductions from other sectors, and either deliver net cost savings or are cost‐effective when compared to other mitigation measures. Retrofits can also provide social and economic benefits, such as improved health and comfort, and lower energy costs. This paper reviews energy use and building retrofits in Canada and argues the following should be implemented: (1) focus innovation on deep energy retrofit processes, not singular retrofit actions; (2) maximize both social and environmental benefits; (3) improve data gathering and availability for analysis and delivery; (4) innovate for a process of decisions and to avoid “dropouts” during the retrofit process; and (5) focus innovation on business models that maximize benefits.     

ECONOMIC ASSESSMENT OF THE SEISMIC RETROFITTING OF LOW-COST APARTMENT BUILDINGS

When structural retrofitting of buildings is required due to seismic safety considerations, building owners or government officials are faced with a crucial decision whether to demolish and rebuild their buildings, or retrofit them. Simple decisions based on fixed proportions, such as demolish and rebuild if retrofit costs exceed 40% of the replacement cost, may be misleading. A financial analysis should be carried out considering all the revenues and costs of the building during its life time. A low-cost residential apartment building that has a construction cost of $140/m² is selected in this study to represent the vulnerable buildings in developing countries under seismic risk. Life-cycle cost analysis approach is employed to value the rebuild or retrofit alternatives to compare economically. Economic assessment has been carried out for various parameters. It has been found that the age of the building and the retrofit ratio are dominant parameters among the others. The critical retrofit ratio (percent of retrofit cost to initial construction cost) varied from 25% for 40 year old buildings to 67% for 10 year old buildings. It is suggested that economical decisons should not be made simply by comparing the retrofit costs to initial construction costs.     

Questioning Polycentric Development and its Effects. Issues of Definition and Measurement for the Italian NUTS-2 Regions

Polycentric development is a widely used term both in academic research and in the normative agenda. However, its theoretical foundations and economic implications are still unclear and the concept of polycentricity still does not have a shared definition or a shared measurement method. The aim of this study is two-fold. First, it defines and measures polycentricity at a NUTS-2 regional level, by comparing functional and morphological methods. Second, in the light of the role assigned to polycentric development in terms of policy, the study investigates the relationships between the degree of regional polycentricity and the key economic variables of performance, namely, competitiveness, social cohesion and environmental sustainability. Our main finding was that functional and morphological methods lead to similar results. In addition, we find a correlation between polycentricity and a more unequal income distribution and a higher level of productivity, especially when polycentricity was measured in functional terms. No stable correlations were found between polycentricity and measures of environmental sustainability, such as land consumption and greenhouse gas emissions.     

Cumulative Ductility Spectra for Seismic Design of Ductile Structures Subjected to Long Duration Motions: Concept and Theoretical Background

A seismic design procedure that does not take into account the maximum and cumulative plastic deformation demands that a structure will likely undergo during severe ground motion could lead to unreliable performance. Damage models that quantify the severity of repeated plastic cycling through plastic energy are simple tools that can be used for practical seismic design. The concept of constant cumulative ductility strength spectra, developed from one such model, is a useful tool for performance-based seismic design. Particularly, constant cumulative ductility strength spectra can be used to identify cases in which low-cycle fatigue may become a design issue, and provides quantitative means to estimate the design lateral strength that should be provided to a structure to adequately control its cumulative plastic deformation demands during seismic response. Design expressions can be offered to estimate the strength reduction factors associated to the practical use of constant cumulative ductility strength spectra.     

The devolution of mudbrick: ethnoarchaeology of abandoned earthen dwellings in the Bolivian Andes

This ethno-geoarchaeological study considers the formation of archaeological deposits through a study of abandoned contemporary mudbrick structures on the Taraco Peninsula, Bolivia. The study site was a domestic compound with rooms for different functions that had been abandoned for over 50 years. Structures were in variable states of decay in terms of roof cover, walling integrity and abandonment fills. Geoarchaeological samples were collected from intact and weathered adobes, earthen hearths, mud plaster, and flooring. Adobes and mud plaster were locally derived from topsoil containing archaeological sediments with added gravel and plant temper. This study found a relatively light anthropogenic signature for decayed earthen houses.Rising damp exfoliated mud plaster despite un-mortared cobble wall foundations. Organic matter from roof fall attracted thriving soil faunal populations, which furthered site destruction through bioturbation, particularly packed earth floors. Sediments derived from weathered mudbrick retained little evidence of prior use as construction materials unless exposed to heat. Sediments exposed to high-temperatures produced the most distinctive rubified features but were structurally compromised. Isolated thermal features from decomposed adobe would not be distinguishable from other hearth types. Adobes exposed to low or moderate heat had few distinctive features in thin section. Intact adobes and floors that were not exposed to heat have fewer pores than natural sediments and distinctive grass inclusions. These adobes disarticulated into loose sediments when exposed to weathering. Adobe fall outside the crumbling structures blended into topsoil.This study sheds light on functional attributes of pre-Columbian construction practices. Thick, fine-textured sterile flooring is commonly encountered in the study region. This would control bioturbation from roof fall in a previous occupation enabling reconstruction in abandoned dwellings. In contrast to the contemporary dwelling, prehistoric mortared cobble foundations would resist rising damp. Cobbles without mortar may relate more to design and construction than durability. These contrasts between contemporary and prehistory construction practices reflect differences in the design, construction costs and functional use-life of adobe structures.     

单檐歇山式木构古建抵抗极端烈度地震试验调查研究

为更好地保护我国古建筑,基于《单檐歇山式古建筑抗震性能振动台试验》的相关成果,研究了强震作用下我国明清官式木构古建的抗震性能,制作了与该论文相同的试验模型,进行了振动台试验。通过对模型输入烈度逐渐增强的1940年El-centro波,并考虑地震波为水平双向作用,分析了强震作用下不同构造的试验现象,开展了详细的震后调查,获得了不同构造在强震作用下的抗震性能和震害机制。结果表明:强震作用下,我国明清官式木构古建的振动形式表现为柱架、斗拱、梁架及屋顶的近似同步往复摇摆;主要震害包括柱底偏移、榫卯节点开裂、拔榫、斗拱偏移及错位、额枋-垫板分离、墙体倒塌等,但承重木构架受损不严重,结构未产生倒塌。其良好抗震性能的原因与古建筑的构造特征密切相关。     

Probabilistic Calibration and Experimental Validation of the Seismic Design Criteria for One-Story Concrete Frames

This article investigates the seismic performance of one-story reinforced concrete structures for industrial buildings. To this aim, the seismic response of two structural prototypes, a cast-in-situ monolithic frame and a precast hinged frame, is compared for four different levels of translatory stiffness and seismic capacity. For these structures an incremental nonlinear dynamic analysis is performed within a Monte Carlo probabilistic simulation. The results obtained from the probabilistic analysis prove that precast structures have the same seismic capacity of the corresponding cast-in-situ structures and confirm the overall goodness of the design criteria proposed by Eurocode 8, even if a noteworthy dependency of the actual structural behavior from the prescribed response spectrum is pointed out.

The experimental verification of these theoretical results is searched for by means of pseudodynamic tests on full-scale structures. The results of these tests confirm the overall equivalence of the seismic behavior of precast and cast-in-situ structures. Moreover, two additional prototypes have been designed to investigate the seismic behavior of precast structures with roof elements placed side by side. The results of these further tests show that an effective horizontal diaphragm action can be activated even if the roof elements are not connected among them, and confirm the expected good seismic performance of these precast systems. Finally, the results of the experimental tests are compared with those obtained from nonlinear structural analyses. The good agreement between numerical and experimental results confirms the accuracy of the theoretical model and, with it, the results of the probabilistic investigation.     

Substitute or addition to hypermobile lifestyles? Second home mobility and Finnish CO2 emissions

Tourism produces an increasing share in global greenhouse gas (GHG) emissions. These are mostly derived from transport emissions, and long-haul air travel in particular. Short-haul domestic tourism is believed by some to be a potential substitute for long-haul tourism. Using the example of Finland this paper examines the extent to which domestic second home tourism can substitute for other leisure trips and therefore contribute to reductions of travel-generated GHG emissions. Survey data are used to evaluate the CO₂ emissions caused by travel to domestic second homes, and to create statistical models that verify if the owners of domestic second homes travel to other leisure destinations less frequently than others, and if they cause less emissions by their leisure mobility than others with comparable economic and demographic background. We find that although the owners and users of domestic second homes travel for other leisure purposes less frequently than others, this does not mean their leisure mobility generates less emissions. Overall, owners of second homes produce significantly more CO₂ by their leisure mobility than non-owners. The use of second homes does not seem to be a substitute for high emission long-haul travels, but rather a part of an overall highly mobile leisure lifestyle. It is therefore necessary to better understand and influence the entire range of individual mobility behaviours in order to reduce travel-related GHG emissions.     

Seismic Performance Assessment of Steel Frames with Shape Memory Alloy Connections,Part II – Probabilistic Seismic Demand Assessment

This article is the second of two companion articles that evaluate the seismic performance of steel moment-resisting frames with innovative beam-to-column connections that incorporate shape memory alloy (SMA) elements to enhance the energy dissipation characteristics of such frames. Building upon the finite element models of the three- and nine-story frames that were developed in the first article, the seismic demands on partially restrained frames with and without SMA elements are evaluated within a probabilistic framework. The results of this evaluation, expressed in the form of demand hazard curves, depict the effectiveness of the SMA connections in enhancing building performance over a range of demand levels. Martensitic SMA connections are most effective in controlling deformation demands on the frame from high levels of seismic intensity. In contrast, the recentering capability of superelastic SMA connections make them most suitable for reducing residual deformations in the structure, a reduction that is achieved at the expense of increased deformation demands during strong excitation. However, neither connection is uniformly beneficial at all hazard levels, suggesting that SMA systems must be tailored to the specific performance objectives for the building structural system.