collapse failure
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Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 79
Author(s):  
Qiuwei Yang ◽  
Zhikun Ba ◽  
Zhuo Zhao ◽  
Xi Peng ◽  
Yun Sun

Blasting impact load may be encountered during the construction of some pile foundation projects. Due to the effect of blasting impact, hole collapse can easily occur in the hole-forming stage of pile foundation construction. In order to prevent hole collapse, it is very necessary to evaluate the stability of a pile hole wall before pile foundation construction. The calculation of hole collapse can usually be attributed to an axisymmetric circular hole stress concentration problem. However, the existing collapse failure theory of pile hole hardly considers the effect of blasting impact load. In view of this, this paper proposes the stability evaluation method of a pile hole wall under blasting impact. Compared with the existing collapse failure theory, the proposed method fully considers the effect of blasting impact stress. Using Mohr–Coulomb strength theory and symmetry analysis, the strength condition of collapse failure is established in this work for accurate evaluation of the stability of a hole wall. The proposed stability evaluation method is demonstrated by a pile foundation construction project of a bridge. Moreover, a shaking table test on the pile hole model was performed to verify the proposed method by experimental data. The results indicate the effectiveness and usability of the proposed method. The proposed method provides a feasible way for the stability analysis of a pile hole wall under blasting impact.


2021 ◽  
Vol 13 (24) ◽  
pp. 13733
Author(s):  
Rubén Galindo ◽  
Miguel Ángel Millán ◽  
Luis E. Hernández-Gutiérrez ◽  
Claudio Olalla Marañón ◽  
Hernán Patiño

The failure criterion of low-density volcanic rocks differs radically from that of conventional rocks by manifesting collapse under isotropic stress. In this way, the shapes of the failure model do not reveal a continuously increasing growth of deviating stress with the isotropic stress, but they reach a maximum value, after which they decrease until they vanish under the isotropic collapse pressure. As a consequence, engineering applications require the implementation of numerical codes and the resolution of associated numerical difficulties. This article presents the problem of the bearing capacity of a foundation on a low-density volcanic rock using the DLO (discontinuity layout optimization) numerical method. The analysis of results shows the ability of the DLO method to solve the numerical difficulties associated with the complex failure criteria, so that the convergence and stability of the solution can be achieved without generating high computational costs. Additionally, a discussion of the DLO results is also presented, demonstrating forms of failure on the ground following the real collapses in these volcanic materials. In addition, numerical validation was performed with the finite difference method, using FLAC, and with an analytical method using simplified configurations, obtaining good contrast results, with the DLO method performing better. In this way, an adequate and reliable resolution technique is provided to face the problem of bearing capacity in low-density volcanic rocks, overcoming limitations referred to in the technical literature regarding the difficulty of treating highly non-linear and non-monotonic numerical criteria, which allows the introduction of isotropic collapse failure.


2021 ◽  
Vol 9 (5A) ◽  
pp. 1-9
Author(s):  
M. M. Nujid ◽  
J. Idrus ◽  
N. F. Bawadi ◽  
A. A. Firoozi

Author(s):  
Lyan-Ywan Lu ◽  
Fu-Pei Hsiao ◽  
Yin-Nan Huang ◽  
Wei-Huan Hsieh

Mid-rise buildings, which may be used as office or apartment buildings, are very common structures in urban areas. Because these buildings are usually heavily populated, the casualty caused by the collapse of these structures in an earthquake could not be overestimated. Therefore, developing a suitable assessment method to identify these buildings with high collapse risk is an important issue. This paper presents a probabilistic assessment method, which involves nonlinear response-history analysis together with incremental dynamic analysis (IDA), to assess the collapse risk of a mid-rise building, so high-risk buildings and their damage patterns can be identified. This methodology is developed based on the procedure of collapse fragility analysis proposed by FEMA P-58, while the local and damage global criteria that define collapse failure are adopted from ASCE 41-13 and PEER-TBI, respectively. Finally, for demonstration, the proposed procedure is applied to assess the collapse risk of a mid-rise RC building that collapsed in a major earthquake occurred in Taiwan, 2016.


2021 ◽  
Vol 123 ◽  
pp. 105266
Author(s):  
Yanfei Chen ◽  
Shaohua Dong ◽  
Zhipeng Zang ◽  
Modi Gao ◽  
Hong Zhang ◽  
...  

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1306
Author(s):  
Jianwu Pan ◽  
Xian Wang ◽  
Hao Dong

The robustness of precast reinforced concrete (RC) frames is relatively poor, while the precast RC frames are strengthened to mitigate progressive collapse, avoiding “strong beams and weak columns” and the anchorage failure of strengthening materials under large deformation condition are the key problems. Aiming to discuss these problems, this paper carried out an experimental research of strengthening on three half-scale assembled monolithic frame subassemblages to mitigate progressive collapse. One specimen was strengthened by implanting carbon fiber rope (CFR) with polymer into concrete, one specimen was strengthened by binding CFR with special knot, and the last one was not strengthened. The failure mode, collapse failure mechanism and strengthening effect of subassemblages were discussed. Analytical models of load capacity increment contributed by CFR and construction suggestions of precast RC frame to mitigate progressive collapse were proposed. The results indicated that none of the strengthened specimens had anchorage failure. The two strengthening methods significantly increased the load capacity of the subassemblages in the catenary action (CA) stage with little effect on the flexural action (FA) stage and compressive arch action (CAA) stage.


Author(s):  
Carlos Mendoza ◽  
José Matos ◽  
Neryvaldo Galvão ◽  
Álvaro Viviescas

<p>External events represent the most common causes of bridge failure which could indicate distress, partial or total collapse (failure of all substantial parts of a bridge). One of the main environmental factors are earthquakes, which have a high impact on bridges due to irregularities presented in both substructure and superstructure and vulnerabilities acquired by the codes used in its design. This article presents a framework to obtain the reliability index of a bridge under seismic events, using response surface method and first order reliability method, based on random variables that affect the structure capacity (pushover analysis) and the seismic loads (peak ground acceleration). The bridge reliability of the case study is updated using visual inspection techniques. Results indicate that the vulnerable zone on the bridge is its shortest pier and the failure could occur due to high shear concentration in the hinge at the bottom of the pier.</p>


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