scholarly journals Rapid Retrofit of Reinforced Concrete Frames after Progressive Collapse to Increase Sustainability

2019 ◽  
Vol 11 (15) ◽  
pp. 4195 ◽  
Author(s):  
Li ◽  
Shan ◽  
Zhang ◽  
Li
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Design Method ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Frame Structure ◽  
Rc Frame ◽  
Concrete Frames ◽  
Before And After ◽  
Test Frame

A structural progressive collapse is usually a local failure, in which the damage is concentrated at beams that bridge the removal column and the column itself. In many cases, retrofitting the damaged structure is more economical and more sustainable than reconstructing the entire structure. A progressive collapse test of a 1/3 scale, four-bay by two-story reinforced concrete (RC) frame was conducted, after which the structure was retrofitted with carbon fiber reinforced polymer (CFRP) wraps and retested. The center column in the first story was removed and the frame was pushed down quasistatically under displacement control to investigate the progressive collapse performances of the retrofitted RC frame. The test results were represented systematically at different areas in terms of the resistance forces, crack developments, and local and global failure modes. Numerical models were built to verify the test frame before and after the retrofitting. A design method was proposed to retrofit an RC frame using CFRP wraps after a progressive collapse. The test frame was redesigned to improve the retrofitting and used as an example to demonstrate the rationality of the proposed retrofit design method. The results indicated that the proposed retrofitting technology rapidly restored the frame structure to its original capacity before the progressive collapse occurred, whilst consistently satisfying the priorities of being economical and sustainable.

Experimental and Numerical Studies on the Reinforced Concrete Frames Subjected to Blast Loads

2012 ◽  
Vol 157-158 ◽  
pp. 1173-1177
Author(s):  
Li Xiao ◽  
Wen Zhong Qu ◽  
Jian Gang Wang
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Computer Code ◽  
Economic Loss ◽  
Frame Structure ◽  
Building Structures ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Blast Response

Terrorist bombing attacks will endanger and may even destroy the target building structures, resulting in economic loss and casualties. Typical columns and floor slab systems are not designed to resist the complex blast loading. So, in recent years, the effects of blast on conventional public buildings are focused on. In this paper,a two-bay,one-story reinforced concrete frame structure which is used to model a portion of a typical reinforced concrete frame structural system is used to investigate the blast response. The experiments are conducted on two models, allowing a variation in explosives standoff and explosives charge. In each experiment,the blast pressure values are recorded and the degree of damage of the frames are studied. According to the two kinds of experiments, two numerical models are established. ALE method which considers the interaction of the explosive, the air, and the structure is applied.Structure response analyses are performed using the large deformation finite-element computer code, LS-DYNA. The numerical results are compared with the experiment results, and a good agreement is obtained. The calculating results also demonstrate that some experimental value is unreasonable.

scholarly journals Strengthening of Precast RC Frame to Mitigate Progressive Collapse by Externally Bonded CFRP Sheets Anchored with HFRP Anchors

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jianwu Pan ◽  
Xian Wang ◽  
Fang Wu
Keyword(s):  
Failure Modes ◽  
Progressive Collapse ◽  
Analytical Models ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Concrete Frames ◽  
Catenary Action ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

Currently, the robustness of precast reinforced concrete frames is attracting wide attention. However, avoiding “strong beams and weak columns” during strengthening against progressive collapse is a key problem. To discuss this problem, an experimental study on two 1/2-scale precast frame subassemblages under a pushdown loading regime was carried out in this paper. One specimen was strengthened with carbon fibre-reinforced polymer (CFRP) sheets on the beam sides. The middle parts of the CFRP sheets were anchored with hybrid fibre-reinforced polymer (HFRP) anchors. Another specimen was not strengthened. The failure mechanisms, failure modes, and strengthening effect are discussed. The strengthening effect is very obvious in the early catenary action stage. No shearing failure develops on HFRP anchors, which proves that the anchoring method is effective. Based on the experimental results, analytical models and preventive strengthening design and construction measures to mitigate progressive collapse of the precast RC frame are proposed.

CRACK RESISTANCE OF PRESTRESSED REINFORCED CONCRETE FRAME STRUCTURE SYSTEMS UNDER SPECIAL IMPACT

2021 ◽  
Vol 93 (1) ◽  
pp. 74-84
Author(s):  
T.A. ILIUSHCHENKO ◽  
◽  
V.I. KOLCHUNOV ◽  
S.S. FEDOROV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Impact Analysis ◽  
Progressive Collapse ◽  
Frame Structure ◽  
Frame Structures ◽  
Reinforced Concrete Frame ◽  
Resistance Development ◽  
Concrete Frame ◽  
Before And After

The results of experimental and theoretical researches of crack resistance, development and growth of cracks of a fragment of a reinforced concrete multi-storey frame of a monolithic building with prestressed beams for a special emergency impact caused by a sudden removal of one of the load-bearing elements are presented. Removal of the middle column of the frame was considered as an emergency impact. Analysis of the pattern cracking in the frames with a prestressed beam before and after a special impact is carried out against the pattern cracking in an unstressed frame structure. Based on the increments of cracks width in the beam, the coefficient of dynamic additional loading in prestressed frame structures from a special impact was calculated. The obtained results of experimental and theoretical researches of the crack resistance of frame structures in considered influences can be used in the development of methods for protecting the frames of monolithic multi-storey buildings against progressive collapse.

scholarly journals Robustness of Reinforced Concrete Frames against Blast-Induced Progressive Collapse

Vibration ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 722-742
Author(s):  
Mattia Francioli ◽  
Francesco Petrini ◽  
Pierluigi Olmati ◽  
Franco Bontempi
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Local Level ◽  
Structural Response ◽  
Frame Structure ◽  
Blast Load ◽  
Response Analysis ◽  
Structural Element ◽  
Global Robustness

A quantitative procedure for the robustness and progressive collapse assessment of reinforced concrete (RC) frames under blast load scenarios is presented. This procedure is supported by multilevel numerical models, including nonlinear numerical analyses of the structural response of both local (i.e., response of the single structural element to the blast load) and global levels (i.e., response of the structural system to the blast-induced damage). Furthermore, the procedure is applied to a 2D RC frame structure. The novelty of the proposed procedure is that the global robustness is evaluated by the so-called “damage-presumption approach” where the considered damages are defined both in typology and extension depending on the blast scenario occurring at the local level. The dedicated local response analysis of a specified blast scenario leads to the proper definition of the so-called “blast-scenario dependent robustness curves”.

Experimental Study on Progressive Collapse Resistance of Reinforced Concrete Frame Structures

2011 ◽  
Vol 71-78 ◽  
pp. 871-875
Author(s):  
Yong Kang Zheng ◽  
Jin Gang Xiong ◽  
Zhao Qiang Wu ◽  
Yi Nong He
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Frame Structure ◽  
Seismic Resistance ◽  
Seismic Demand ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Collapse Resistance ◽  
Reinforced Concrete Frame Structures

The progressive collapse of the frame structure is simulated with testing a 1/3 scale, 4×2-bay and 3-storey reinforced concrete spatial frame in this paper. The experimental model was designed according to the non-seismic resistance demand, and the middle-side column of the bottom floor was replaced by a mechanical jack to simulate its initial local damage. Based on the experimental results, the applied load process and the load transferring mechanism of the model frame are analyzed. The progressive collapse-resisting performance of reinforced concrete frames with non-seismic demand are obtained.

Resistance of Reinforced Concrete Frames with Masonry Infill Walls to In-Plane Vertical Loading

2016 ◽  
Vol 711 ◽  
pp. 982-988
Author(s):  
Alex Brodsky ◽  
David Z. Yankelevsky
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Progressive Collapse ◽  
Lateral Loading ◽  
Masonry Walls ◽  
Reinforced Concrete Frame ◽  
Masonry Infill ◽  
Concrete Frame ◽  
Vertical Loading ◽  
Infill Masonry

Numerous studies have been conducted on the in plane behavior of masonry infill walls to lateral loading simulating earthquake action on buildings. The present study is focused on a problem that has almost not been studied regarding the vertical (opposed to lateral) in-plane action on these walls. This may be of concern when a supporting column of a multi-storey reinforced concrete frame with infill masonry walls undergoes a severe damage due to an extreme loading such as a strong earthquake, car impact or military or terror action in proximity to the column. The loss of the supporting column may cause a fully or partly progressive collapse to a bare reinforced concrete frame, without infill masonry walls. The presence of the infill masonry walls may restrain the process and prevent the development of a progressive collapse. The aim of the present study is to test the in-plane composite action of Reinforced Concrete (RC) frames with infill masonry walls under vertical loading through laboratory experiments and evaluate the contributions of infill masonry walls, in an attempt to examine the infill masonry wall added resistance to the bare frame under these circumstances. Preliminary results of laboratory tests that have been conducted on reinforced concrete infilled frames without a support at their end, under monotonic vertical loading along that column axis will be presented. The observed damages and failure modes under vertical loading are clearly different from the already known failure modes observed in the case of lateral loading.

Research on the Collapse Performance of RC Frame Structure

2014 ◽  
Vol 556-562 ◽  
pp. 712-715
Author(s):  
Jing Zhao ◽  
Jing Zhao ◽  
Xing Wang Liu
Keyword(s):  
Reinforced Concrete ◽  
Frame Structure ◽  
Rc Frame ◽  
Hydraulic Actuator ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Load Paths ◽  
Rc Frame Structure ◽  
Gravity Load ◽  
Middle Column

In collapse-resistant design of a structure under accidental local action, it is important to understand the failure mechanism and alternative load paths. In this paper, a pseudo-static experimental method is proposed. Based on which, the collapse of frame structure was simulated with testing a 1/3 scale; 4-bay and 3-story plane reinforced concrete frame. In the experience, the middle column of the bottom floor was replaced by mechanical jacks to simulate its failure, and the simulated superstructure’s gravity load acted on the column of the top floor by adopting a servo-hydraulic actuator with force –controlled mode.

Blast Vulnerability Assessment of Road Tunnels with Reinforced Concrete Liners

2018 ◽  
Vol 2672 (41) ◽  
pp. 156-164 ◽  
Author(s):  
Fengtao Bai ◽  
Qi Guo ◽  
Kyle Root ◽  
Clay Naito ◽  
Spencer Quiel
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Transportation Network ◽  
Computational Effort ◽  
Public Access ◽  
Tunnel Current ◽  
Circular Tunnel ◽  
Inflection Points ◽  
Road Tunnels

Tunnels are a critical component of our transportation infrastructure, and unexpected damage to a tunnel can significantly and adversely impact the functionality of a transportation network. Tunnel systems are vulnerable to potential threats of intentional and accidental blast events because of their relatively unrestricted public access. These events can lead to spalling and breach of the tunnel liner which, depending on the surrounding media, can result in local damage and progressive collapse of the tunnel. Current approaches for evaluating blast-induced damage to a tunnel liner either require significant computational effort or oversimplification such that accurate spatial distributions of damage cannot be obtained. This study presents an effective approach to predict and map the damage to a reinforced concrete liner of a roadway tunnel from various explosive threat sizes and tunnel geometries. A literature review of existing studies is conducted, and potential scenarios of blast events are examined with varying charge position and size. Rectangular, horseshoe, and circular tunnel geometries, each with the same traffic throughput, are evaluated. An efficient analytical approach to determine the spatial distribution of blast-induced spall and breach damage is presented and shows good agreement with numerical models analyzed in LS-DYNA. The proposed approach is then used to examine the relationship between increasing blast hazard intensity and the extent of spall and breach damage. Inflection points in this relationship can be used to identify hazard levels at which a progressive collapse evaluation would be warranted.

Base-Isolated Multi-Storey Reinforced Concrete Frame Structure Modal Analysis

2012 ◽  
Vol 204-208 ◽  
pp. 869-871
Author(s):  
Cai Hua Wang ◽  
Hui Jian Li ◽  
Jian Feng Wu
Keyword(s):  
Reinforced Concrete ◽  
Modal Analysis ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Frame Structure ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Reinforced Concrete Frame Structure ◽  
Before And After ◽  
Isolation Device

The multi-storey reinforced concrete frame structure used lead rubber pad as the base isolation device. The paper had modal analysis of base-isolated multi-storey reinforced concrete frame structure using the ANSYS software. Comparing the frequency and vibration mode before and after isolation under El-Centro wave, It concluded the leader rubber pad have seismic isolation effect for multi-storey reinforced concrete frame structure .

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