scholarly journals Collapse Scenarios of High-Rise Buildings Using Plastic Limit Analysis

2009 ◽  
Vol 2009 ◽  
pp. 1-9
Author(s):  
G. Liu ◽  
D. K. Liu ◽  
W. K. Chow
Keyword(s):  
New York ◽  
Limit Analysis ◽  
Terrorist Attack ◽  
World Trade Center ◽  
Limit Load ◽  
Plastic Limit ◽  
High Rise ◽  
Plastic Limit Analysis ◽  
Large Fires ◽  
International Experts

The Twin Towers of the World Trade Center (WTC) in New York, USA collapsed on 11 September, 2001. The incident is regarded as the most severe disaster for high-rise buildings in history. Investigations into the collapse scenarios are still being conducted. Possible collapse scenarios assessed by local and international experts were reported. Another possible collapse scenario of the WTC based on two hypotheses was proposed in this paper, and the idea of plastic limit analysis was applied to evaluate the approximate limit load. According to the theory analysis and numerical calculations, a conclusion can be drawn that the large fires, aroused by the terrorist attack, play a significant role on the collapse of the WTC.

Plastic Limit Analysis of Piping with Local Wall-Thinning under Elevated Temperature

2016 ◽  
Vol 725 ◽  
pp. 47-52
Author(s):  
Xian He Du ◽  
Ying Hua Liu
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Limit Analysis ◽  
Limit Load ◽  
Plastic Limit ◽  
Wall Thinning ◽  
Plastic Limit Analysis ◽  
Creep Time ◽  
Plastic Limit Load ◽  
Local Wall Thinning

In order to evaluate the safety and integrity of piping with local wall-thinning at elevated temperature, a numerical method for plastic limit load of modified 9Cr-1Mo steel piping is proposed in the present paper. The limit load of piping at high temperature is defined as the load-carrying capacity after the structure has served for a certain time period. The power law creep behavior with Liu-Murakami damage model is implemented into the commercial software ABAQUS via CREEP for simulation, and the Ramberg-Osgood model is modified to consider the material deterioration effect of modified 9Cr-1Mo steel by introducing the creep damage factor into the elasto-plastic constitutive equation. For covering the wide ranges of defect ratios and service time periods, various 3-D numerical examples for the piping with local wall-thinning defects, and creep time are calculated and analyzed. The limit loads of the defected structures under high temperature are obtained through classic zero curvature criterion with the modified Ramberg-Osgood model, and the typical failure modes of these piping are also discussed. The results show that the plastic limit load of piping containing defect at elevated temperature depends not only on the size of defect, but also on the creep time, which is different from the traditional plastic limit analysis at room temperature without material deterioration.

Plastic limit analysis with non linear kinematic strain hardening for metalworking processes applications

2011 ◽  
Vol 25 (11) ◽  
pp. 2859-2870 ◽  
Author(s):  
Ali Chaaba ◽  
Lahbib Bousshine ◽  
Mohamed Aboussaleh ◽  
Hassan El Boudaia
Keyword(s):  
Strain Hardening ◽  
Limit Analysis ◽  
Plastic Limit ◽  
Non Linear ◽  
Plastic Limit Analysis

Shakedown and Limit Analysis of Kinematic Hardening Piping Elbows Under Internal Pressure and Bending Moments

2021 ◽  
Author(s):  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Yield Strength ◽  
Internal Pressure ◽  
Limit Analysis ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Bending Moments ◽  
Plastic Limit ◽  
Plastic Limit Load ◽  
Interaction Curves ◽  
Shakedown Limit

Abstract In this paper, the Stress Compensation Method (SCM) adopting an elastic-perfectly-plastic (EPP) material is further extended to account for limited kinematic hardening (KH) material model based on the extended Melan's static shakedown theorem using a two-surface model defined by two hardening parameters, namely the initial yield strength and the ultimate yield strength. Numerical analysis of a cylindrical pipe is performed to validate the outcomes of the extended SCM. The results agree well with ones from literature. Then the extended SCM is applied to the shakedown and limit analysis of KH piping elbows subjected to internal pressure and cyclic bending moments. Various loading combinations are investigated to generate the shakedown limit and the plastic limit load interaction curves. The effects of material hardening, elbow angle and loading conditions on the shakedown limit and the plastic limit load interaction curves are presented and analysed. The present method is incorporated in the commercial finite element simulation software and can be considered as a general computational tool for shakedown analysis of KH engineering structures. The obtained results provide a useful information for the structural design and integrity assessment of practical piping elbows.

scholarly journals Reliability Based Analysis and Optimum Design of Laterally Loaded Piles

2017 ◽  
Author(s):  
Majid Movahedi Rad
Keyword(s):  
Limit Analysis ◽  
Strain Energy ◽  
Load Capacity ◽  
Optimization Procedure ◽  
Load Parameter ◽  
Plastic Limit ◽  
Laterally Loaded Piles ◽  
Plastic Limit Analysis ◽  
Complementary Strain ◽  
Laterally Loaded

In this study reliability based limit analysis is used to determine the ultimate capacity of laterally loaded piles.  The aim of this study is to evaluate the lateral load capacity of free-head and fixed-head long pile when plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, uncertain bound on the complementary strain energy of the residual forces is also applied. This bound has significant effect for the load parameter. The solution to reliability-based problems is based on a direct integration technique and the uncertainties are assumed to follow Gaussian distribution. The optimization procedure is governed by the reliability index calculation.

Shakedown and Limit Analysis of Kinematic Hardening Piping Elbows Under Inner Pressure and Bending Moments

2020 ◽  
Author(s):  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Yield Strength ◽  
Limit Analysis ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Bending Moments ◽  
Plastic Limit ◽  
Inner Pressure ◽  
Plastic Limit Load ◽  
Interaction Curves ◽  
Shakedown Limit

Abstract The stress compensation method (SCM) for shakedown and limit analysis was previously proposed and applied to elastic-perfectly plastic (EPP) piping elbows. In this paper, the SCM is extended to account for limited kinematic hardening (KH) material model based on the extended Melan’s static shakedown theorem using a two-surface model defined by two hardening parameters: initial yield strength and ultimate yield strength. To validate the extended SCM, a numerical test on a cylinder pipe is performed. The results agree well with ones from literature. Then the extended SCM is applied to the shakedown and limit analysis of KH piping elbows subjected to inner pressure and cyclic bending moments. Various loading combinations are investigated to create the shakedown limit and plastic limit load interaction curves. The effects of the material hardening, angle of the elbow and loading conditions on the shakedown limit and plastic limit load interaction curves are presented and analysed. The present method is incorporated in the commercial software of Abaqus and can be considered as a general computational tool for shakedown analysis of KH engineering structures. The obtained results provide a useful information for the structural design and integrity assessment of practical piping elbows.

scholarly journals Safety Assessment of Masonry Arch Bridges Considering the Fracturing Benefit

2020 ◽  
Vol 10 (10) ◽  
pp. 3490 ◽  
Author(s):  
Federico Accornero ◽  
Giuseppe Lacidogna
Keyword(s):  
Fracture Mechanics ◽  
Bearing Capacity ◽  
Limit Analysis ◽  
Life Assessment ◽  
Plastic Limit ◽  
Masonry Arch ◽  
Fracturing Process ◽  
Plastic Limit Analysis ◽  
Elastic Fracture ◽  
Arch Bridges

The evolutionary analysis of the fracturing process is an effective tool to assess of the structural bearing capacity of masonry arch bridges. Despite their plain basic assumptions, it must be remarked that elastic analysis and plastic or limit analysis can hardly be used to describe the response and predict damage for moderate or service load levels in masonry arch bridges. Therefore, a fracture mechanics-based analytical method with elastic-softening regime for masonry is suitable in order to study the global structural behaviour of arch bridges, highlighting how the arch thrust line is affected by crack formation, and the maximum admissible load evaluated by means of linear elastic fracture mechanics is larger than the load predicted by elasticity theory. Such an increment in terms of bearing capacity of the arch bridge can be defined “fracturing benefit”, and it is analogous to the “plastic benefit” of the plastic limit analysis. The fracturing process, which takes into account the fracture initiation and propagation in the masonry arch bulk, occurs before the set-in of the conditions established by means of the plastic limit analysis. In the present paper, the study of the elastic-fracture-plastic transitions is performed for three monumental masonry arch bridges with different shallowness and slenderness ratios. This application returns an accurate and effective whole service life assessment of masonry arch bridges, and more in general it can be suitable for a great number of historical masonry structures still having strategic or heritage importance in the infrastructure systems.

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