scholarly journals Post-Breakage Vibration Frequency Analysis of In-Service Pedestrian Laminated Glass Modular Units

Vibration ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 836-852
Author(s):  
Chiara Bedon ◽  
Salvatore Noè
Keyword(s):  
Vibration Frequency ◽  
Numerical Models ◽  
Limit State ◽  
Design Stage ◽  
Glass Layer ◽  
Ultimate Limit State ◽  
Equivalent Material ◽  
Laminated Glass ◽  
Modular Units ◽  
Vibration Performance

The vibration performance of pedestrian structures has attracted the attention of several studies, especially with respect to unfavourable operational conditions or possible damage scenarios. Specific vibration comfort levels must be commonly satisfied in addition to basic safety requirements, depending on the class of use, the structural typology and the materials involved. Careful consideration could be thus needed at the design stage (in terms of serviceability and ultimate limit state requirements), but also during the service life of a given pedestrian system. As for structural health monitoring purposes, early damage detection and maintenance interventions on constructed facilities, vibration frequency estimates are also known to represent a preliminary but rather important diagnostic parameter. In this paper, the attention is focused on the post-breakage vibration analysis of in-service triple laminated glass (LG) modular units that are part of a case-study indoor walkway in Italy. On-site non-destructive experimental methods and dynamic identification techniques are used for the vibration performance assessment of a partially cracked LG panel (LGF), compared to an uncracked modular unit (LGU). Equivalent material properties are derived to account for the fractured glass layer, and compared with literature data for post-breakage calculations. The derivation of experimental dynamic parameters for the post-breakage mechanical characterization of the structural system is supported by finite element (FE) numerical models and parametric frequency analyses.

scholarly journals Structural analisys of concrete pre-stressed reservoirs for sludge fermentation – water waste treatment plant bucharest – glina. numerical fem assessment of the structural response for static in-duty loads

2013 ◽  
Vol 9 (1) ◽  
pp. 42-58
Author(s):  
Tudor Bugnariu
Keyword(s):  
Waste Treatment ◽  
Numerical Models ◽  
Limit State ◽  
Treatment Plant ◽  
Structural Response ◽  
Soil Mass ◽  
Ultimate Limit State ◽  
Element Analysis ◽  
Waste Treatment Plant ◽  
Water Waste

Abstract The paper refers to a structural finite element analysis on the reservoirs for sludge fermentation subjected to static in-duty loads, at Glina Water Waste Treatment Plant. The purpose was to assess the stress and deformation states in subsequent erection and service conditions, to verify the design provisions and to emphasize the sensitivities, for a structure which was designed in the ‘80s based on analytical procedures. The results obtained on the numerical models highlight the importance of the soil-structure interaction, in peculiar the one influenced by the soil mass deformability, on the overall structural response. Based on the calculated stresses, all structural components were verified according to the actual design codes at the ultimate limit state and the service limit state (water tightness/crack emergence).

Lessons for steel structures from the 2009 earthquake damage in Padang

2010 ◽  
Vol 43 (2) ◽  
pp. 134-139 ◽  
Author(s):  
Clark W. K. Hyland ◽  
Sugeng Wijanto
Keyword(s):  
Earthquake Engineering ◽  
Limit State ◽  
Steel Structures ◽  
Building Code ◽  
Design Stage ◽  
Ultimate Limit State ◽  
Structural Elements ◽  
Audit Process ◽  
Moment Resisting ◽  
Code Enforcement

The Padang earthquake is a timely reminder to New Zealand structural engineers of a number of things with respect to seismic design and construction practice of steel structures. These include: The importance of implementing the latest seismic loadings and design technology into new and existing structures without undue delay; The need to maintain an effective Building Code enforcement and audit process, including the keeping of publicly transparent compliance records; The important role of the design engineer in observing and auditing the interpretation and implementation of the design is essential, to prevent improper substitution of materials and ill-considered design changes; The need for ongoing continuing professional development and education for design, construction and building code enforcement officials to develop and maintain technical competency; The separation of non-structural elements from interfering with the primary seismic resisting system needs to be carried through diligently from design and into construction. Where structural separation is not achieved then design models for integrating unreinforced brickwork panels within moment resisting frames need to be developed, particularly for retrofit situations; The design for weak-axis bending of two way moment resisting steel frames requires careful attention to secondary effects, and should be avoided where possible; Non-self centring structural elements need to be identified at design stage and designed to minimise inelastic behaviour during ultimate limit state earthquakes; Diagonal bracing rods should be designed to avoid failure within couplings. Consideration should also be given to the dynamic response of the roof level bracing system to heavy wall induced lateral loads; Connections at the interface of steel work with concrete and masonry sub-trades need to be carefully monitored to ensure intended design performance is achieved; Unreinforced masonry without lateral tiebacks should be avoided on lintels over egress-ways; A guide of typical structural repair methods would also be a useful tool for post-earthquake use, to quickly identify appropriate repair strategies and allow repair estimates to be developed. At a philosophical level, should a post-earthquake repair be required to simply allow a resumption of functionality? Alternatively should the repair be required to reinstate the structural performance to its pre-earthquake strength? Or should the repair improve the seismic resisting performance of the structure in line with current earthquake engineering knowledge?

Design, construction and structural response of a lightweight FRP footbridge

2021 ◽  
Author(s):  
Christian Gallegos-Calderón ◽  
Javier Naranjo-Pérez ◽  
M. Dolores G. Pulido ◽  
Iván M. Díaz
Keyword(s):  
Limit State ◽  
Structural Response ◽  
Design Stage ◽  
Ultimate Limit State ◽  
A Value ◽  
Vertical Vibrations ◽  
Frp Strips ◽  
Glass Frp ◽  
Design Construction

<p>This paper presents the design, construction and structural response of a laboratory FRP footbridge. Pultruded elements, Glass-FRP profiles and Carbon-FRP strips, comprise the 10 m long simply supported structure, which linear mass is only 80 kg/m approximately. A value of <i>L</i>/200 (<i>L </i>being the length of the span) was the limit adopted for the long-term deflection at mid-span, and verifications at Ultimate Limit State were carried out according to the recommendations of the FRP manufacturer and the European Guideline to design FRP Structures. To construct the bridge, the following phases were completed: (i) bonding CFRP strips to the GFRP stringers, (ii) connecting the FRP elements, (iii) casting concrete at the support regions, and (iv) installing the deck. Once the construction finished, an experimental static and dynamic campaign was performed to assess the bridge structural behavior. As expected from the design stage, excessive vertical vibrations under different pedestrian actions (walking and bouncing) were measured.</p>

scholarly journals A Comparison of Shell and Solid Finite Element Models of Austenitic Stainless Steel Columns in Compression

2021 ◽  
Vol 1203 (3) ◽  
pp. 032048
Author(s):  
Daniel Jindra ◽  
Zdeněk Kala ◽  
Jiří Kala
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Numerical Models ◽  
Limit State ◽  
Material Model ◽  
Nonlinear Material ◽  
Experimental Program ◽  
Ultimate Limit State ◽  
Geometric Characteristics ◽  
Nonlinear Stress

Abstract The subject of this article is the implementation of new knowledge on material and geometric characteristics obtained from an experimental research program in advanced numerical modelling of compressed columns made of austenitic stainless steel using the ANSYS Classic software. Nonlinear stress–strain curves were obtained using our own experimental program and studied in terms of identifying the most suitable nonlinear material model. Additional material and geometric characteristics were obtained from literature and other independent research. Numerical models differing in mesh density localization, formulation of element integration, non-linear material model, and initial geometric imperfections were created and compared. The aim of the models was the ultimate limit state of a strut of circular hollow cross-section stressed by compression and analysed using the geometrically and materially nonlinear solution with consideration to the influence of initial imperfections. Static resistance and limit state deformations are compared for each model. The paper presents the analysis of model uncertainty by comparing SHELL and SOLID FE models, which must be characterized before the start of the analysis of the random influence of imperfections on the limit states. The mean values and the coefficients of variation are practically the same for both approaches. In summary, the presented models can be considered sufficiently validated and eligible for integration in tandem with simulation sampling methods.

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

scholarly journals Fragility curves for Italian URM buildings based on a hybrid method

2021 ◽  
Author(s):  
A. Sandoli ◽  
G. P. Lignola ◽  
B. Calderoni ◽  
A. Prota
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Limit State ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Seismic Behaviour ◽  
Building Stock ◽  
Ground Acceleration ◽  
Damage Scenario

AbstractA hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions. Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building’s class has been chosen as an Intensity Measure to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minimum value of PGAs defined for each building class. To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber macroseismic intensity scale has been used and the corresponding fragility curves developed. Results show that the proposed building’s classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods.

Combined flexure and torsion of I-shaped steel beams

1989 ◽  
Vol 16 (2) ◽  
pp. 124-139 ◽  
Author(s):  
Robert G. Driver ◽  
D. J. Laurie Kennedy
Keyword(s):  
Limit State ◽  
Bending Moment ◽  
Phase Behaviour ◽  
Inelastic Interaction ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Second Phase ◽  
Design Standards ◽  
Limit States ◽  
Interaction Diagram

Design standards provide little information for the design of I-shaped steel beams not loaded through the shear centre and therefore subjected to combined flexure and torsion. In particular, methods for determining the ultimate capacity, as is required in limit states design standards, are not presented. The literature on elastic analysis is extensive, but only limited experimental and analytical work has been conducted in the inelastic region. No comprehensive design procedures, applicable to limit states design standards, have been developed.From four tests conducted on cantilever beams, with varying moment–torque ratios, it is established that the torsional behaviour has two distinct phases, with the second dominated by second-order geometric effects. This second phase is nonutilizable because the added torsional restraint developed is path dependent and, if deflections had been restricted, would not have been significant. Based on the first-phase behaviour, a normal and shearing stress distribution on the cross section is proposed. From this, a moment–torque ultimate strength interaction diagram is developed, applicable to a number of different end and loading conditions. This ultimate limit state interaction diagram and serviceability limit states, based on first yield and on distortion limitations, provide a comprehensive design approach for these members. Key words: beams, bending moment, flexure, inelastic, interaction diagram, I-shaped, limit states, serviceability, steel, torsion, torque, ultimate.

Anchor rod forces and maximum bending moments in sheet pile walls using the factored strength approach

1996 ◽  
Vol 33 (5) ◽  
pp. 815-821 ◽  
Author(s):  
A B Schriver ◽  
A J Valsangkar
Keyword(s):  
Water Pressure ◽  
Limit State ◽  
Bending Moment ◽  
Ultimate Limit State ◽  
Sheet Pile ◽  
Limit States ◽  
Working Stress ◽  
Geotechnical Design ◽  
Ultimate Limit State Design ◽  
Sheet Pile Wall

Recently, the limit states approach using factored strength has been recommended in geotechnical design. Some recent research has indicated that the application of limit states design using recommended load and strength factors leads to conservative designs compared with the conventional methods. In this study the influence of sheet pile wall geometry, type of water pressure distribution, and different methods of analysis on the maximum bending moment and achor rod force are presented. Recommendations are made to make the factored strength design compatible with conventional design. Key words: factored strength, working stress design, ultimate limit state design, anchored sheet pile wall, bending moment, anchor rod force.

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