Search results for "Structural Engineering"
showing 10 items of 1998 documents
Simplified Model to Predict Runoff Generation Time for Well-Drained and Vegetated Soils
2016
The study of generation process of subsurface stormflow, typical of well-drained and high permeable soils, can be theoretically carried out by applying the continuity and the motion equations with the appropriate boundary conditions. However, difficulties and uncertainness on determining soil hydraulic properties and soil physics heterogeneities let this way not always feasible. In a different way, processes dynamic can be derived by the local scale through a coarse graining procedure, allowing to preserve medium motion character, while hydraulic fluctuation of the motion are lost. Following an approach as this, in this paper a simplified model to predict the runoff generation time, the so-…
An Innovative Structural Dynamic Identification Procedure Combining Time Domain OMA Technique and GA
2022
In this paper an innovative and simple Operational Modal Analysis (OMA) method for structural dynamic identification is proposed. It combines the recently introduced Time Domain–Analytical Signal Method (TD–ASM) with the Genetic Algorithm (GA). Specifically, TD–ASM is firstly employed to estimate a subspace of candidate modal parameters, and then the GA is used to identify the structural parameters minimizing the fitness value returned by an appropriately introduced objective function. Notably, this method can be used to estimate structural parameters even for high damping ratios, and it also allows one to identify the Power Spectral Density (PSD) of the structural excitat…
Improving energy efficiency of commercial buildings by Combined Heat Cooling and Power plants
2020
Abstract Commercial buildings play a key-role in the energy consumption of the building sectors. Recent statistics have shown that as the number of commercial buildings is continuously increasing, their effects on energy consumption are expected to grow. These buildings are characterized by high energy demand mainly due to lighting and HVAC requirements. Rooms of energy saving exist by considering that: (i) electricity demands and HVAC requirements occur simultaneously during the day and (ii) both demands are currently satisfied by using separate energy systems. It is apparent that the adoption of polygeneration systems could represent a valid solution to achieve energy savings. To this aim…
Reliability Analysis of a Controlled Stage-Constructed and Reinforced Embankment on Soft Ground Using 2D and 3D Models
2020
Geosynthetic reinforcement has become a very practical technique to improve geotechnical structure safety. In spite of improved soil behavior, structures are affected by uncertainties related to soil and reinforcement material properties. This paper aims to present a reliability analysis in order to take statistical information (uncertainties) into account in a safety analysis of reinforced embankments. The analysis was used in a case study on a controlled stage-constructed embankment on soft ground in order to investigate its probabilistic stability. Modeling was performed by commercial geotechnical software usage (GeoStudio and RocScience packs, SIGMA/W+SLOPE/W and SLIDE³, respectively) a…
Assessment of bioavailability and effects of chemicals due to remediation actions with caging mussels (Anodonta anatina) at a creosote-contaminated l…
2002
A study was conducted at Lake Jämsänvesi in Central Finland, to identify the potential ecotoxicological risks of the remediation operation of a creosote-/PAH-contaminated lake sediment, made by capping during the years 1998-1999. Mussels (Anodonta anatina) were deployed to the lake at the same time as the remediation operation was started in November 1998. The contaminated area (0.5 ha) was covered by a filter geotextile (polypropylene), gravel and sand (1-1.5m) which were spread out on the ice and let to sink onto the bottom of the lake when the ice melted in May 1999. The possible impacts of capping to the adjacent environment were assessed from mussels exposed and particulate material se…
Uptake of organic xenobiotics by benthic invertebrates from sediment contaminated by the pulp and paper industry
2007
Abstract Uptake of pulp and paper mill-derived pollutants by benthic invertebrates from sediment in Southern Lake Saimaa, eastern Finland, was studied. Two groups of benthic invertebrates (Diptera and Oligochaeta) were analyzed for their concentrations of resin acids (RAs), chlorophenolics (CPs) and β -sitosterol. The samples were collected 1 and 3 km downstream from the mill. In laboratory experiments Chironomus plumosus (a dipteran) and Lumbriculus variegatus (oligochaete) were exposed for 14 d to sediments collected from the same locations. The concentrations of RAs, CPs and β -sitosterol were higher in the areas downstream from the mill than those in the upstream reference area in both …
LONG-TERM STRUCTURAL DEFICIENCIES IN A MAT FOUNDATION ON CLAY SOIL
2013
A 3-story building with a mat foundation consisting of a slab on a grid of grade beams performed poorly on clay soil. Cracking of the slab became rogressively worse as a result of the incorrect esign and fluctuations in the groundwater pressure under the foundation. The cyclic presence and absence of water rusted the steel reinforcement, and the sulfates in the clay soil caused formation of ettringite in the concrete. Plastic hinges formed in the slab and settlements occurred, causing damage to the beams. The situation is still in progress and may lead to the collapse of the structure under normal service conditions. The geotechnical and structural investigations performed to survey and ass…
Bond characterization of monolithic and layered glass panels and ultrasonic tests to control glued surfaces
2019
Abstract An experimental investigation is presented regarding the compressive and shear strength of monolithic and PVB laminated glass elements connected by acrylic glue. Ultrasonic tests were also used to control the efficiency of glued surfaces of glass panels. Twenty-four triplets composed of three float glass elements glued with acrylic adhesive were prepared to perform bond tests. Of these twelve triplets were made with monolithic glass elements with a nominal thickness of 20 mm, while twelve were made with layered glass elements 20 mm thick. Three single elements of monolithic glass and three of layered glass were tested for compressive strength. Ultrasonic tests were performed on a s…
The influence of the mean stress on fatigue life of 10HNAP steel under random loading
2001
Abstract This paper contains the results of uniaxial random load fatigue tests with different mean values performed on 10HNAP steel specimens. The experimental fatigue life was compared with the life determined according to different methods of amplitude transformation of the cycles. Cycles were counted with the rain flow algorithm and damage was cumulated with the Palmgren–Miner hypothesis. It has been shown that in the case of “symmetric” stress histories with zero expected values, the mean values of selected cycles do not strongly influence the calculated fatigue life and transformation of the cycle amplitudes; hence, no mean stress correction for cycle mean values different from zero is…
Fatigue crack propagation from a cold-worked hole
2007
Abstract The cold expansion process is widely used to enhance the fatigue life of structures with fastener holes. Various studies assert that the cold expansion improves the fatigue strength of fastener holes; however, the improvement of fatigue life is difficult to quantify. Therefore, the influence on fatigue life of cold-worked process was studied by numerical and experimental tests. Then, a parametric study on material hardening behavior and Bauschinger’s parameter was performed for several loading conditions in order to determine their effect on crack growth propagation. The results of the numerical tests have exhibited a good prediction of the fatigue life of the component.