scholarly journals Safety and quality assurance for geotechnical constructions in urban areas

2019 ◽  
Author(s):  
Steffen Leppla ◽  
Rolf Katzenbach
Keyword(s):  
Quality Assurance ◽  
Urban Areas ◽  
Construction Projects ◽  
Soil Structure ◽  
Engineering Practice ◽  
The Finite Element Method ◽  
Existing Structures ◽  
Geotechnical Structures ◽  
Load Tests

Safety and quality assurance are the most important aspects for the design and the construction of geotechnical structures. These aspects consider the optimisation by reducing the resources material, money and time. For construction projects with a distinctive soil-structure interaction in the vicinity of existing structures special methods have to be applied to guarantee safety and quality. Therefor numerical simulations using the Finite-Element-Method (FEM), in-situ load tests on the construction site, special foundation techniques like the Combined Pile-Raft Foundation (CPRF), the observational method and an independent peer review are necessary. The paper explains the application and the combination of these tools by examples from engineering practice.

scholarly journals Study on the Bearing Capacity and Engineering Performance of Aeolian Sand

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Han Xia ◽  
Jingtao Zhang ◽  
Jun Cai ◽  
Huangsong Pan ◽  
Xuesen She
Keyword(s):  
Bearing Capacity ◽  
Soil Structure ◽  
Soil Layer ◽  
Aeolian Sand ◽  
Mu Us Desert ◽  
Large Numbers ◽  
Loose Soil ◽  
Load Tests ◽  
Physical And Mechanical Characteristics

The climate in the aeolian desert has great differences from that in other regions, generally showing large diurnal temperature differences and extremely dry and low groundwater level characteristics. Therefore, the physical and mechanical characteristics of the sand are different from those of other regions, and it has a loose soil structure, large pores, and a low bearing capacity. To ensure the security and applicability of engineering, it is necessary to study the engineering characteristics of aeolian sand. This paper focuses on the bearing capacity parameters of aeolian sand in the Mu Us Desert, and test sites in 6 weak foundation areas are selected. Large numbers of basic soil mechanical parameters have been collected through in situ static load tests (SLT) and laboratory confined compaction tests (CCT) to evaluate the effect of foundation treatments. The results show that the characteristics of aeolian sand in the Mu Us Desert include low moisture, poor cohesion, and easy compaction. The mud and water content affect the bearing capacity of aeolian sand. For weak foundations, adding a geogrid or replacing a weak soil layer with stone and aeolian sand can significantly improve the bearing capacity.

Evaluation of the Vulnerability Index for Unreinforced Masonry Structures

2012 ◽  
Vol 166-169 ◽  
pp. 1387-1390 ◽  
Author(s):  
Fouzia Djaalali ◽  
Mahmoud Bensaibi ◽  
Noreddine Bourahla
Keyword(s):  
Urban Areas ◽  
Structural Parameters ◽  
Vulnerability Index ◽  
Index Method ◽  
Technical Data ◽  
Vulnerability Index Method ◽  
Existing Structures ◽  
Steel Framing ◽  
The Sixties

Buildings constructed before the sixties in Algerian urban areas, are typically low and mid rise multi-storey buildings made of stone and/or brick masonry walls or infill light steel framing. These types of buildings are known to be vulnerable to seismic effects. Within this paper, an assessment of such existing structures, using the “Vulnerability Index” method is presented. This allows a good classification and description of the seismic quality of the structures taking into account both, structural and non structural parameters considered to be ones of the main parameters governing the vulnerability of the structure. A technical data sheet, including all information that might be used in an associated computer program in Delphi is subsequently developed. The results obtained show that the established classification confirms the observed information in situ.

scholarly journals A Study of UVER in Santiago, Chile Based on Long-Term In Situ Measurements (Five Years) and Empirical Modelling

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 368
Author(s):  
Lisdelys González-Rodríguez ◽  
Amauri Pereira de Oliveira ◽  
Lien Rodríguez-López ◽  
Jorge Rosas ◽  
David Contreras ◽  
...  
Keyword(s):  
Urban Areas ◽  
Solar Spectrum ◽  
Sun Exposure ◽  
Great Accuracy ◽  
In Situ Measurements ◽  
Uv Index ◽  
Empirical Modelling ◽  
The People

Ultraviolet radiation is a highly energetic component of the solar spectrum that needs to be monitored because is harmful to life on Earth, especially in areas where the ozone layer has been depleted, like Chile. This work is the first to address the long-term (five-year) behaviour of ultraviolet erythemal radiation (UVER) in Santiago, Chile (33.5° S, 70.7° W, 500 m) using in situ measurements and empirical modelling. Observations indicate that to alert the people on the risks of UVER overexposure, it is necessary to use, in addition to the currently available UV index (UVI), three more erythema indices: standard erythemal doses (SEDs), minimum erythemal doses (MEDs), and sun exposure time (tery). The combination of UVI, SEDs, MEDs, and tery shows that in Santiago, individuals with skin types III and IV are exposed to harmfully high UVER doses for 46% of the time that UVI indicates is safe. Empirical models predicted hourly and daily values UVER in Santiago with great accuracy and can be applied to other Chilean urban areas with similar climate. This research inspires future advances in reconstructing large datasets to analyse the UVER in Central Chile, its trends, and its changes.

scholarly journals Reliability Estimation of Reinforced Slopes to Prioritize Maintenance Actions

2021 ◽  
Vol 18 (2) ◽  
pp. 373
Author(s):  
Farshad BahooToroody ◽  
Saeed Khalaj ◽  
Leonardo Leoni ◽  
Filippo De Carlo ◽  
Gianpaolo Di Bona ◽  
...  
Keyword(s):  
Urban Areas ◽  
Evaluation Method ◽  
Likelihood Function ◽  
Reliability Estimation ◽  
Analytical Models ◽  
Geotechnical Structures ◽  
Reinforced Slopes ◽  
The Stability ◽  
Methods Analytical ◽  
Asset Managers

Geosynthetics are extensively utilized to improve the stability of geotechnical structures and slopes in urban areas. Among all existing geosynthetics, geotextiles are widely used to reinforce unstable slopes due to their capabilities in facilitating reinforcement and drainage. To reduce settlement and increase the bearing capacity and slope stability, the classical use of geotextiles in embankments has been suggested. However, several catastrophic events have been reported, including failures in slopes in the absence of geotextiles. Many researchers have studied the stability of geotextile-reinforced slopes (GRSs) by employing different methods (analytical models, numerical simulation, etc.). The presence of source-to-source uncertainty in the gathered data increases the complexity of evaluating the failure risk in GRSs since the uncertainty varies among them. Consequently, developing a sound methodology is necessary to alleviate the risk complexity. Our study sought to develop an advanced risk-based maintenance (RBM) methodology for prioritizing maintenance operations by addressing fluctuations that accompany event data. For this purpose, a hierarchical Bayesian approach (HBA) was applied to estimate the failure probabilities of GRSs. Using Markov chain Monte Carlo simulations of likelihood function and prior distribution, the HBA can incorporate the aforementioned uncertainties. The proposed method can be exploited by urban designers, asset managers, and policymakers to predict the mean time to failures, thus directly avoiding unnecessary maintenance and safety consequences. To demonstrate the application of the proposed methodology, the performance of nine reinforced slopes was considered. The results indicate that the average failure probability of the system in an hour is 2.8×10−5 during its lifespan, which shows that the proposed evaluation method is more realistic than the traditional methods.

scholarly journals Special Issue “Applications of Finite Element Modeling for Mechanical and Mechatronic Systems”

2021 ◽  
Vol 11 (11) ◽  
pp. 5170
Author(s):  
Marek Krawczuk ◽  
Magdalena Palacz
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Engineering Practice ◽  
The Finite Element Method ◽  
Special Issue ◽  
Mechatronic Systems ◽  
Modeling And Analysis ◽  
Modern Engineering ◽  
Concise Description

Modern engineering practice requires advanced numerical modeling because, among other things, it reduces the costs associated with prototyping or predicting the occurrence of potentially dangerous situations during operation in certain defined conditions. Different methods have so far been used to implement the real structure into the numerical version. The most popular have been variations of the finite element method (FEM). The aim of this Special Issue has been to familiarize the reader with the latest applications of the FEM for the modeling and analysis of diverse mechanical problems. Authors are encouraged to provide a concise description of the specific application or a potential application of the Special Issue.

Failure by corrosion in PC bridges: a case history of a viaduct in Italy

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Piero Colajanni ◽  
Antonino Recupero ◽  
Giuseppe Ricciardi ◽  
Nino Spinella
Keyword(s):  
Prestressed Concrete ◽  
Design Methodology ◽  
Progressive Collapse ◽  
Numerical Analyses ◽  
Existing Structures ◽  
History Of ◽  
Progressive Collapse Analysis ◽  
Practical Implications ◽  
Post Tensioned

Purpose The paper illustrates a viaduct collapse due to corrosion phenomena. Moreover, a contribution to the issues related to both the control of existing structures and design methods to be followed for the construction of new buildings is provided. Design/methodology/approach The objectives were achieved by in situ observations and numerical analyses. The effects of corrosion phenomena are investigated, and the progressive collapse analysis is provided to be helpful in this case. Findings The damages induced by corrosion phenomena have caused the collapse of the viaduct taken in to account. The performed numerical analyses were able to reproduce the effects of corrosion in terms of reduction of wires diameter. Research limitations/implications The research is limited to prestressed concrete viaduct with post-tensioned cables. Practical implications A monitoring plan, subdivided in several phases, is suggested, to avoid critical situations as these described. Originality/value The case study brought useful information on the effects of corrosion on the decks section, showing how the technology in post-tensioned cables is usually insidious and prone to the issues relating to corrosion of the wires

Urban and Rural Logistics and Distribution System Based on Supply and Marketing Cooperatives

2012 ◽  
Vol 253-255 ◽  
pp. 1468-1471 ◽  
Author(s):  
Xiao Ling Huang ◽  
Hao Xiang Jia ◽  
Philippe Roiseux Racine
Keyword(s):  
Rural Areas ◽  
Distribution System ◽  
Urban Areas ◽  
Construction Projects ◽  
Living Condition ◽  
Living Standards ◽  
Agricultural Products ◽  
Logistics System ◽  
Supply And Marketing Cooperatives ◽  
Marketing Cooperatives

China is a vast country with 800 million farmers. An amelioration of their general living condition is a pressing issue. In China, it is not uncommon to encounter lower grain price due to the delays in their transportation. There are many reasons for the low living standards in rural areas, the obsolete rural logistic system, especially regarding agricultural products, is obviously one of them. Recently, to improve logistics development conditions of China's agricultural products, every levels of government increased rural logistics investment in construction projects; however, there are still delay issues from the productions centers to the urban areas. This paper looks the breaks in the logistics chain by studying the current distribution style, and proposes logistics system based on supply and marketing cooperatives in order to improve the existing system.

Toward CO2 and CH4 measurements by ground-based observations of surface-scattered sunlight

2021 ◽  
Author(s):  
Benedikt Hemmer ◽  
Christin Proß ◽  
Stanley P. Sander ◽  
Thomas J. Pongetti ◽  
Zhao-Cheng Zeng ◽  
...  
Keyword(s):  
Los Angeles ◽  
Urban Areas ◽  
Near Infrared ◽  
Chem Phys ◽  
Retrieval Algorithm ◽  
Los Angeles Basin ◽  
Satellite Measurements ◽  
Precise Knowledge ◽  
Extended Sources

<div> <div>Precise knowledge of sources and sinks in the carbon cycle is desired to understand its sensitivity to climate change and to account and verify man-made emissions. In this context, extended sources like urban areas play an important role. While in-situ measurements of carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) are highly accurate but localized, satellites measure column-integrated concentrations over an extended footprint. The CLARS-FTS [1, 2] stationed at the Mt. Wilson observatory looking downward into the Los Angeles basin has pioneered an innovative measurement technique that fills the sensitivity gap between in-situ and satellite measurements. The technique enables mapping the urban greenhouse gas concentration fields by collecting spectra of ground scattered sunlight and scanning through the region.</div> <div> </div> <div>Here, we report on progress developing a portable setup for a CLARS-FTS-like measurement geometry. The instrument is based on the EM27/SUN FTS with a modified pointing technique and a more sensitive detector. The retrieval algorithm is based on the RemoTeC software, previously employed for solar backscatter satellite measurements. We discuss first steps in terms of instrument performance and retrieval exercises. For the latter, we have carried out simulations on how the neglect of scattering by the retrieval affects the retrieved boundary layer concentrations of CO<sub>2</sub> and CH<sub>4</sub> for an ensemble of hypothetical scenes with variable complexity in aeorsol loadings and viewing geometry. We also report on a test to apply RemoTeC to a small set of CLARS-FTS spectra collected throughout the Los Angeles basin.</div> <div> </div> <div><em>References</em></div> <div>[1] Fu, D. et al., 2014: Near-infrared remote sensing of Los Angeles trace gas distributions from a mountaintop site, Atmos. Meas. Tech., 7, 713–729, https://doi.org/10.5194/amt-7-713-2014</div> [2] Wong, K. W. et al., 2015: Mapping CH4 : CO2 ratios in Los Angeles with CLARS-FTS from Mount Wilson, California, Atmos. Chem. Phys., 15, 241–252, https://doi.org/10.5194/acp-15-241-2015</div>

Developing an integrated framework for optimization of spatial requirements of construction equipment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
S. Hemalattha ◽  
R. Vidjeapriya
Keyword(s):  
Construction Projects ◽  
Indoor Environment ◽  
Outdoor Environment ◽  
Building Information Modelling ◽  
Actual Structure ◽  
Content Type ◽  
Space Planning ◽  
Existing Structures ◽  
Building Information

PurposeThis study aims to develop a framework for optimizing the spatial requirements of the equipment in a construction site using a geographic information system (GIS).Design/methodology/approachAn ongoing construction project, an existing thermal powerplant in India, is considered to be the case study, and the corresponding construction activities were scheduled. The equipment spaces were defined for the scheduled activities in building information modelling (BIM), which was further imported to GIS to define the topology rules, validate and optimize the spatial requirements. The BIM simulates the indoor environment, which includes the actual structure being constructed, and the GIS helps in modelling the outdoor environment, which includes the existing structures, temporary facilitates, topography of the site, etc.; thus, this study incorporates the knowledge of BIM in a geospatial environment to obtain optimized equipment spaces for various activities.FindingsSpace in construction projects is to be considered as a resource as well as a constraint, which is to be modelled and planned according to the requirements. The integration of BIM and GIS for equipment space planning will enable precise identification of the errors in the equipment spaces defined and also result in fewer errors as possible. The integration has also eased the process of assigning the topology rules and validating the same, which otherwise is a tedious process.Originality/valueThe workspace for each activity will include the space of the equipment. But, in most of the previous works of workspace planning, only the labour space is considered, and the conflicts and congestions occurring due to the equipment were neglected. The planning of equipment spaces cannot be done based only on the indoor environment; it has to be carried out by considering the surroundings and topography of the site, which have not been researched extensively despite its importance.

Driven cast-in-situ pile capacity: insights from dynamic and static load testing

2021 ◽  
Author(s):  
Kevin N. Flynn ◽  
Bryan A. McCabe
Keyword(s):  
Dynamic Load ◽  
Shear Stresses ◽  
Load Testing ◽  
Pile Capacity ◽  
Compression Load ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Cast Concrete ◽  
Load Tests

Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

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