Incremental wave analysis and its application to performance-based assessment of jacket platforms

In this paper, a relatively novel approach is established to estimate different limit states and accurate behavior of jacket platforms against environmental wave loading. This novel approach which is called Incremental Wave Analysis (IWA) can be an appropriate substitute to current pushover practice. The IWA can take into account the effects of variation in wave height and wave-in-deck loading in the estimating of platforms' behavior. This paper aims to introduce the applications of this approach in deterministic assessment of offshore platforms, comprehensively. The IWA can estimate the collapse-prevention limit state of jacket platforms properly. In addition, an appropriate parameter for ultimate capacity of offshore platforms is introduced which is called Collapse Wave Height (CWH). It is illustrated that the CWH can be utilized as a substitute to RSR parameter in the design and assessment of jacket platforms. Moreover, this novel indicator is able to exceptionally estimate the collapse probability of offshore platforms utilizing a deterministic practice. This is a unique feature that can never be achieved by current pushover method utilizing RSR parameter. The IWA can be carried out using either nonlinear static or dynamic wave analyses. Therefore, in this paper, both Static and Dynamic Incremental Wave Analyses (SIWA and DIWA) will be systematically explained. Before conducting DIWA, some fundamental questions such as importance of dynamic analysis and also proper methodology for conducting dynamic analysis, will be investigated. Comparison between SIWA and DIWA will also bring about worthwhile results which will be discussed thoroughly.     

Pile-soil-structure interaction in pushover analysis of jacket offshore platforms using fiber elements

In this paper, pushover analysis of fixed jacket offshore platforms with the application of “Fiber Elements” which are capable of modeling post-buckling behavior of braces has been conducted and case study on two functional jacket offshore platforms in the Persian Gulf region has been performed. Two-dimensional models of the mentioned platforms are simulated using “DRAIN-3DX” software and the wave force is considered as the lateral load pattern on the structures.In this paper, pushover analysis of jacket offshore platforms is performed by developing numerical models that incorporate different foundation conditions for considering pile-soil-structure interaction. Increasing the displacement of the platforms and recording the relative load factors by incorporating the displacement control method is the basis for performing the analysis. In order to consider the importance of pile-soil interaction, six individual cases are examined which include pile-soil interaction analysis with actual soil in-situ characteristics. Pile head fixed below mud line elevation, pile head hinged below mud line elevation, application of linear pile stubs, application of non-linear pile-stubs & finally a combination of linear and non-linear pile-soil characteristics.In the analyses performed herein, the condition in which pile-soil interaction is considered is set to be the base case. The results from incorporating the non-linear pile stub have the most compatibility with the base case. Application of Linear pile stubs and the combination of linear and non-linear pile has much deviation with the base case. Ultimate strength of the platform in the non-linear pile stub case was very close to the base case.     

Landsliding in seismic areas: the case of the Acquara-Vadoncello landslide (southern Italy)

On 29 December 1993, a slump-earthflow was activated in the outskirts of Senerchia (southern Italy) in a locality named "Vadoncello". Mass movement has been active until the time of writing, at a variable rate. Maximum velocity was reached during 1995, when a seismic sequence of low magnitude (maximum 3.6) was recorded. The landslide evolution was studied considering both the characteristics of seismic activity and slope stability conditions. The results of the analyses showed that the role of seismic action in triggering mass movement is uncertain, although it cannot be excluded. Slope behaviour is more likely to have been controlled by morphological and hydrogeological factors and their modifications, which could also have been responsible for the vulnerability of the slope. In conclusion, the mass movement observed in 1995, triggered by the possible contribution of low magnitude shocks repeated at short intervals, determined new and more stable equilibrium conditions in the slope.     

Corrosion damage of a reinforced concrete jetty structure in the Persian Gulf: a case study

One of the most aggressive environments for reinforced concrete (RC) is a marine environment such as that in the Persian Gulf region. In these conditions, reinforcement corrosion due to diffusion of chloride ions is the main deterioration mechanism. This paper presents the results of a study of a 30 year RC jetty structure in Bandar e-Imam Port, in the Persian Gulf region. Concrete durability factors were investigated using conventional and non-destructive tests to obtain the intensity of deterioration. The results showed extensive deterioration due to chloride-induced corrosion. It caused great deduction for service life in this structure. Although this structure was repaired in the past few years, poor repair work and materials caused intensity of corrosion damage rather than control of it.     

Emergency housing in the aftermath of Hurricane Katrina: an assessment of the FEMA travel trailer program

Hurricane Katrina devastated the Gulf Coast of the United States in 2005. More than 1800 persons died, and the disaster stands as the costliest in U.S. history. Over 200,000 former residents of New Orleans continue to reside elsewhere. The U.S. Federal Emergency Management Agency (FEMA) emergency housing program, and specifically the design, manufacture, and deployment of its travel trailer housing units, remain the subject of controversy. The FEMA travel trailer program is critiqued, as is recent empirical evidence on the deleterious health outcomes experienced by many trailer occupants. The results of a pilot investigation are reported, whereby the post-occupancy assessments of a group of occupants of single-site FEMA trailer installations were compared to a group residing in two FEMA trailer park communities in New Orleans. Among the findings, the travel trailer unit was assessed by occupants as difficult to personalize to occupants’ preferred patterns of use, inadequate in size, affording few site amenities, and little overall privacy, and the unit itself functioned as a source of chronic environmental stress. The findings are translated into a theoretical/operative model of person-environment interactions, to assist in further research on this subject.

Serviceability assessment of electrical power transmission systems under probabilistically stated seismic hazards: case study for Shelby County,Tennessee

Scenario earthquakes are often used to evaluate seismic vulnerability of civil infrastructure systems. While the results of such a vulnerability assessment are useful in visualising and explaining the impact of earthquakes on public infrastructure, they are conditional in nature and do not capture the risk to infrastructure systems from the seismicity that may threaten them during a specified service period. Thus, vulnerability assessments based on scenario earthquakes are not as useful for annualising insurance costs, or for designing or retrofitting infrastructure systems. In this paper, a new method to evaluate the unconditional seismic risk to infrastructure systems is proposed and is illustrated through an application to an electrical power transmission system in a region of moderate seismicity. A comparative assessment of the vulnerability of the same system to two commonly used scenario earthquakes–the so-called Maximum Probable Earthquake and Mean Characteristic Earthquake–highlights the advantages of the proposed approach.     

A case study of seismic forward prospecting based on the tunnel seismic while drilling and active seismic methods

Bulletin of Engineering Geology and the Environment - Forward prospecting to predict the location of high-risk geological zones during tunnel boring machine (TBM) tunneling is important for safe...     

Life cycle assessment: A case study of a dwelling home in Scotland

The article provides a life cycle assessment (LCA) of a 3-bed room semi detached house in Scotland. Detailed LCA of five main construction materials i.e. wood, aluminium, glass, concrete and ceramic tiles have been provided to determine their respective embodied energy and associated environmental impacts. Embodied energy of various construction materials involved has been estimated to be equal to 227.4 GJ. It is found that concrete, timber and ceramic tiles are the three major energy expensive materials involved. It as been calculated that concrete alone consumes 65% of the total embodied energy of the home while its share of environmental impacts is even more crucial.     

Groundwater interaction in the coastal environment: hydrochemical,electrical and seismic approaches

The heterogeneous Plio-Quaternary coastal aquifer of the Mamora Basin is the most significant reservoir of Morocco. It is composed of sandstones, conglomerates, limestones and more or less argillaceous sands. The increase in the requirements for water in this area requires further information on the relations between the geometry of the aquifer and the salinity of the water. A hydrochemical analysis was undertaken and highlighted three zones of high mineralization. A geophysical approach allowed the determination of the principal aquifer levels, the localization of the various types of water (fresh, brackish and salt) and the geometry of the aquifer base. The results obtained by these two approaches provide a better image of the phenomena governing the groundwater flows and their interactions      

Probabilistic analysis of uncertainties in seismic hazard assessment

Sources and current methods of analysis of uncertainty from randomness, fuzziness and ignorance or incomplete knowledge in seismic hazard assessment problem are briefly discussed at beginning; understandings of the authors are then presented in the following order. All three types of uncertainty come from incomplete knowledge. Probabilistic method can be applied to all of them, objective probability for random factors and subjective probability for the other two types of uncertain factors. Discrete subjective probability mass functions for incomplete and fuzzy factors can be obtained from logic-tree and membership functions respectively. Fractile curves may be used to show the scattering of any uncertainty factor, but a unified probabilistic treatment may be applied to any combination of all three types of uncertainty.     

Thermal comfort assessment and application of radiant cooling: A case study

A field assessment of thermal comfort was conducted at Mehran University of Engineering and Technology, situated in the subtropical region of Pakistan. The results show that people of the area were feeling thermally comfortable at effective temperature of 29.85 °C (operative temperature 29.3 °C). A comparison of this neutral effective temperature was made with the neutral effective temperature determined from adaptive models. It is found that the neutral effective temperature determined during this study closely match that of the adaptive model based on either indoor temperature or both indoor and outdoor temperatures. The results of thermal acceptability assessment show that more than 80% of occupants were satisfied at an effective temperature of 32.5 °C, which is 6.5 °C above the upper boundary of ASHRAE thermal comfort zone. Naturally ventilated classrooms and air-conditioned offices of the University were simulated using TRNSYS system simulation program for two cases, once when conventional air-conditioning is used for providing thermal comfort, and when comfort is achieved through radiant cooling. In the simulation, cooling tower was used to regenerate cooling water for the radiant cooling system. Energy consumption was estimated from simulation of both cases. The results show that it is possible to achieve thermal comfort for most of the time of the year through the use of radiant cooling without a risk of condensation of moisture from air on the radiant cooling surfaces. A comparison of the energy consumption estimates show that savings of 80% is possible in case thermal comfort is achieved through radiant cooling instead of conventional air-conditioning.     

Life cycle assessment of a single-family residential building in Canada: A case study

The present study quantified the significant environmental impacts of a two-story residential building located in Vancouver, Canada, with a projected 60-year life span: (i) an inventory of all the construction materials was analyzed, covering the building structure and exterior and interior envelopes as well as the energy consumption; (ii) four types of functional units were defined; (iii) the five top building materials were examined, and a sensitivity analysis was conducted to investigate the impact associated with the choice of building materials. Two life cycle phases, manufacturing and operation, were more significant in all of the impact categories, and two building assemblies, the walls and the roof, bore most of the environmental loads. In terms of the sensitivity analysis, the roofing asphalt had the largest impact, dominating three of the seven selected impact categories. Despite different definitions of functional units, the function of the dwelling buildings is always the same, to provide protection and housing for their habitants. Additionally, to improve the performance of an existing building, several strategies were proposed for the building renovation and maintenance, including alternative replacement materials regarding the building components with high environmental burdens, good patterns of the occupants’ consumption behaviors as well as considerations of the financial and environmental cost. Finally, limitations and challenges are discussed to explore better design decisions in future studies.     

Potential for wastewater reuse in irrigation: case study from Aden (Yemen)

Wastewater treatment with waste stabilization ponds (WSP) is a very efficient, low cost and low maintenance operation. The treated wastewater from WSP should be considered as a valuable resource for reuse by water resources managers. Yemen’s water resources are currently experiencing a crisis, because all surface water and groundwater resources are exploited beyond the level of recharge. Promoting water reuse of treated wastewater for irrigation could mitigate this water crisis. This paper assesses the performance of a WSP in the city of Aden by examining the quality of treated sewage predominantly of domestic origin. A comparison with international guidelines reveals that it is possible to use the final effluent to a limited extent in irrigation. This paper includes an outline of the social, religious and political reasons for the water crisis, and explores the idea of reuse of effluent for different irrigation practices.     

Life cycle assessment of wood wastes: A case study of ephemeral architecture

One of the most commonly used elements in ephemeral architecture is a particleboard panel. These types of wood products are produced from wood wastes and they are used in temporary constructions such as trade fairs. Once the event is over, they are usually disposed into landfills. This paper intends to assess the environmental effects related to the use of these wood wastes in the end-of-life stage. The Life Cycle Assessment (LCA) of two scenarios was performed, considering the recycling of wood waste for particleboard manufacture and energy generation from non-renewable resources (Scenario 1) versus the production of energy from the combustion of wood waste and particleboard manufacture with conventional wooden resources (Scenario 2). A sensitive analysis was carried out taking into account the influence of the percentage of recycled material and the emissions data from wood combustion. According to Ecoindicator 99 methodology, Damage to Human Health and Ecosystem Quality are more significant in Scenario 2 whereas Scenario 1 presents the largest contribution to Damage to Resources. Between the two proposed alternatives, the recycling of wood waste for particleboard manufacture seems to be more favorable under an environmental perspective.     

In situ tests for water quality assessment: a case study in Pampean rivers

Two invertebrate species (Hyalella curvispina and Palaemonetes argentinus) and one macrophyte (Egeria densa) from a naturally high nutrient content system (Pampean rivers of La Plata, Argentina) were evaluated for their potential use in situ assays aiming to assess changes in water quality. Invertebrates were individually placed in cylindrical chambers in polluted sections of rivers and in reference upstream sites. Mortality after 48 h was high in polluted and reduced in control sites. Mortality was also higher in situ assays than in laboratory static tests. Standard sections of the macrophyte were also deployed at the reference and control sites. Growth (7 days) in terms of mass increment (but not in length) was consistently reduced in polluted sites. Results of benthic invertebrate and periphitic algae surveys were consistent with the in situ tests: pollution resulted in a decrease in the number of taxa, taxa replacement and in changes in the value of the biotic indices Indice Biótico PAMPeano and Indice de Diatomeas Pampeano, indicating deterioration of water quality. In situ assays have a high potential as environmental tools in integrated approaches of bioassessment programs.     

Weight-of-evidence evaluation in environmental assessment: Review of qualitative and quantitative approaches

Assessments of human health and ecological risk draw upon multiple types and sources of information, requiring the integration of multiple lines of evidence before conclusions may be reached. Risk assessors often make use of weight-of-evidence (WOE) approaches to perform the integration, whether integrating evidence concerning potential carcinogenicity, toxicity, and exposure from chemicals at a contaminated site, or evaluating processes concerned with habitat loss or modification when managing a natural resource. Historically, assessors have relied upon qualitative WOE approaches, such as professional judgment, or limited quantitative methods, such as direct scoring, to develop conclusions from multiple lines of evidence. Current practice often lacks transparency resulting in risk estimates lacking quantified uncertainty. This paper reviews recent applications of weight of evidence used in human health and ecological risk assessment. Applications are sorted based on whether the approach relies on qualitative and quantitative methods in order to reveal trends in the use of the term weight of evidence, especially as a means to facilitate structured and transparent development of risk conclusions from multiple lines of evidence.     

Engineering geological approach to the evaluation of seismic risk in metropolitan regions: case study of Patras,Greece

The city of Patras in western Greece has experienced several destructive earthquakes during the past centuries. The engineering geological conditions of the area have been analyzed and described using a relational geotechnical database management system including geotechnical and geological information obtained from exploratory boreholes, cone penetration tests and cross hole seismic prospecting. The foundation soils of the city were grouped into individual geotechnical units and several engineering geological maps and geotechnical cross sections were compiled. Criteria are proposed for the approximate evaluation of the effect of local soil conditions on ground motion, especially on the distribution of amplification features.      

钢管混凝土组合筒体结构抗震性能试验研究

进行了1个钢管混凝土组合筒体结构模型的抗震性能试验.模型为比例1∶10的13层钢管混凝土组合筒体结构,外筒为钢管混凝土框支框筒结构,内筒为钢筋混凝土核心筒结构.将模型等效为两自由度体系,分别进行了地震波峰值加速度为0.22 g,0.40 g,0.62 g和1.0 g共4种工况的抗震性能动力试验.研究表明,钢管混凝土组合简体结构是一种具有良好抗震性能的结构体系.     

Drift-based fragility assessment of confined masonry walls in seismic zones

The paper presents drift-based fragility curves developed for confined masonry (CM) walls, which are the main structural components for the lateral load-resisting systems employed in housing dwellings in Latin-America. Drift-based fragility curves were developed for two key damage states associated with the structural performance and repairability of CM walls, from experimental results of 118 confined masonry specimens tested under lateral cyclic loading, during research programs carried out in Mexico, Chile, Peru, Venezuela and Colombia. In particular, four sources of uncertainty, due to specimen-to-specimen, finite-sample, measured diagonal compression strength of the masonry and wall height-to-length aspect ratio were included. These fragility curves are very useful for assessing the seismic vulnerability of CM structures, and for estimating the earthquake-induced economic losses employing recently proposed methodologies based on aggregating the estimated damage at the component level for a specific structure.