An RHT-Model-Based Equivalent Parameter Scheme for Blast Response Simulation of RC Frames

2021 ◽  
Author(s):  
Ziqi Tang ◽  
Shanglin Yang ◽  
Run Zhang ◽  
Xiaohu Yao
Keyword(s):  
Response Analysis ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Model Based ◽  
Rc Frames ◽  
Multiple Components ◽  
Equivalent Parameter ◽  
Blast Response ◽  
Constitutive Parameters ◽  
Parameter Scheme

In this paper, a novel equivalent parameter scheme based on the Riedel–Hiermaier–Thoma (RHT) model is proposed for blast response simulations of reinforced concrete (RC) frames. Considering the strengthening effect of longitudinal and stirrup reinforcements on concretes, constitutive parameters in the RHT model are modified to homogenize RC components based on reasonable simplifications and numerical tests. Numerical results of RC beams illustrate that this scheme significantly improves the computational efficiency and effectively predicts real explosion response behaviors with high accuracy. The scheme is then employed for the blast simulation of an RC frame with multiple components with results compared with those of real frame experiments to further demonstrate its reliability. Owing to its efficiency and accuracy, the present RHT-model-based equivalent parameter scheme can serve as a feasible tool to conduct blast response analysis of the RC frame and guide the corresponding anti-explosion designs.

scholarly journals Strengthening of Precast RC Frame to Mitigate Progressive Collapse by Externally Anchored Carbon Fiber Ropes

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1306
Author(s):  
Jianwu Pan ◽  
Xian Wang ◽  
Hao Dong
Keyword(s):  
Carbon Fiber ◽  
Load Capacity ◽  
Progressive Collapse ◽  
Analytical Models ◽  
Deformation Condition ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Catenary Action ◽  
Rc Frames ◽  
Collapse Failure

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.

Restoring Force Model of Joints of RC Frame Retrofitted by FRP

2012 ◽  
Vol 256-259 ◽  
pp. 693-696
Author(s):  
Peng Li ◽  
Ya Ping Peng ◽  
Er Lei Yao
Keyword(s):  
Seismic Performance ◽  
Seismic Retrofitting ◽  
Frame Structure ◽  
Force Model ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Restoring Force ◽  
Rc Frames ◽  
Restoring Force Model ◽  
Hysteretic Performance

In order to evaluate the seismic performance of reinforced concrete (RC) frames retrofitted by FRP, the experiment of RC frames retrofitted at joints by FRP was carried out. The enhancement in seismic performance of the retrofitted frames is evaluated in hysteretic performance, bearing capacity, stiffness degradation and energy dissipation. And the strengthening effect of the frame retrofitted by CFRP and C/GFRP was compared in the experiment. The restoring force model of RC frame joints retrofitted with FRP was proposed and ranges of the characteristic parameters were determined. The equation of restoring force model for joints strengthened by C/GFRP was suggested. The result show that seismic performance of RC frame retrofitted by FRP based on joints can be improved remarkably. The restoring force model which proposed can be used in seismic elasto-plastic analysis of RC frame structure retrofitted by FRP and practical engineering seismic retrofitting design by FRP.

A Hysteretic Model of Conventional Steel Braces and an Analysis of the Collapse Prevention Effect of Brace Strengthening

2012 ◽  
Vol 174-177 ◽  
pp. 3-10 ◽  
Author(s):  
Sheng Nan Huang ◽  
Xin Zheng Lu ◽  
Lie Ping Ye
Keyword(s):  
Dynamic Analysis ◽  
Incremental Dynamic Analysis ◽  
Hysteretic Behavior ◽  
Fragility Analysis ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Hysteretic Model ◽  
Collapse Prevention ◽  
Conventional Steel ◽  
Rc Frames

A hysteretic model of conventional steel braces consisting of 18 parameters is proposed. This model is able to simulate the hysteretic behavior of conventional steel braces accurately. The collapse-prevention strengthening effect with steel braces for a typical reinforced concrete (RC) frame that was close to the epicenter and collapsed during the Great Wenchuan Earthquake is discussed via push-over analysis and collapse fragility analysis based on incremental dynamic analysis. The result could be referred to for the seismic collapse prevention design of RC frames.

Seismic performance of RC frames strengthened by RC infill walls

2021 ◽  
pp. 136943322199772
Author(s):  
Shao-Ge Cheng ◽  
Yi-Xiu Zhu ◽  
Wei-Ping Zhang
Keyword(s):  
Masonry Walls ◽  
Rc Frame ◽  
Seismic Line ◽  
Shake Table Tests ◽  
Infill Walls ◽  
Displacement Ductility ◽  
Rc Frames ◽  
Story Drift ◽  
Comparison Of The Results ◽  
Bending Failure

This study presents the shake-table tests of a 1/5-scaled RC frame retrofitted with RC infill walls. The intensity of input ground motions increased gradually to comprehensively evaluate the structural seismic behavior. We performed a comparison of the results from the RC frame with masonry walls and that with RC walls. The results showed that the presence of RC infills effectively improved the lateral structural stiffness and loading capacity of the frames and reduced their damage and story drift. RC walls acted as the first seismic line of defense, and their failure was dominated by bending failure and concentrated on the low stories. The displacement ductility of the structure decreased with increasing stiffness of the introducing infills.

scholarly journals Physical parametrisation of fire-spotting for operational fire spread models: response analysis with a model based on the Level Set Method

2018 ◽  
Author(s):  
Inderpreet Kaur ◽  
Anton Butenko ◽  
Gianni Pagnini
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Discrete Event ◽  
Fire Spread ◽  
Response Analysis ◽  
System Specification ◽  
Time Step ◽  
Processing Scheme ◽  
Model Based ◽  
The Many

Abstract. Fire-spotting is often responsible for a dangerous flare up in the wildfire and causes secondary ignitions isolated from the primary fire zone leading to perilous situations. In this paper a complete physical parametrisation of fire-spotting is presented within a formulation aimed to include random processes into operational fire spread models. This formulation can be implemented into existing operational models as a post-processing scheme at each time step, without calling for any major changes in the original framework. In particular, the efficacy of this formulation has already been shown for wildfire simulators based on an Eulerian moving interface method, namely the Level Set Method (LSM) that forms the baseline of the operational software WRF-SFIRE, and for wildfire simulators based on a Lagrangian front tracking technique, namely the Discrete Event System Specification (DEVS) that forms the baseline of the operational software FOREFIRE. The simple and computationally less expensive parametrisation includes the important parameters necessary for describing the landing behavior of the firebrands. The results from different simulations with a simple model based on the LSM highlight the response of the parametrisation to varying fire intensities, wind conditions and different firebrand radii. The contribution of the firebrands towards increasing the fire perimeter varies according to different concurrent conditions and the simulation results prove to be in agreement with the physical processes. Among the many rigorous approaches available in literature to model the firebrand transport and distribution, the approach presented here proves to be simple yet versatile for application to operational fire spread models.

scholarly journals Numerical Modeling of Masonry-infilled RC Frame

2019 ◽  
Vol 13 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Christiana A. Filippou ◽  
Nicholas C. Kyriakides ◽  
Christis Z. Chrysostomou
Keyword(s):  
Cyclic Loading ◽  
Numerical Model ◽  
Constitutive Models ◽  
Control Analysis ◽  
Rc Frame ◽  
Initial Stiffness ◽  
Element Analysis ◽  
Rc Frames ◽  
Rc Frame Structures ◽  
Infilled Rc Frames

Background: The behavior of masonry-infilled Reinforced Concrete (RC) frame structures during an earthquake, has attracted the attention of structural engineers since the 1950s. Experimental and numerical studies have been carried out to investigate the behavior of masonry-infilled RC frame under in-plane loading. Objective: This paper presents a numerical model of the behavior existing masonry-infilled RC frame that was studied experimentally at the University of Patra. The objective of the present study is to identify suitable numerical constitutive models for each component of the structural system in order to create a numerical tool to model the masonry infilled RC frames in-plane behavior by accounting the frame-infill separation. Methods: A 2D masonry-infilled RC frame was developed in DIANA Finite Element Analysis (FEA) software and an eigenvalue and nonlinear structural cyclic analyses were performed. It is a 2:3 scale three-story structure with non-seismic design and detailing, subjected to in-plane cyclic loading through displacement control analysis. Results: There is a good agreement between the numerical model and experimental results through a nonlinear cyclic analysis. It was found that the numerical model has the capability to predict the initial stiffness, the ultimate stiffness, the maximum shear-force capacity, cracking- patterns and the possible failure mode of masonry-infilled RC frame. Conclusion: Therefore, this model is a reliable model of the behavior of masonry-infilled RC frame under cyclic loading including the frame-infill separation (gap opening).

Cyclic Performance of Two-Story Ductile RC Frames With Infill Walls

2005 ◽  
Author(s):  
Yung-Hsin Yeh ◽  
Wen-I Liao
Keyword(s):  
Model Building ◽  
General Purpose ◽  
Rc Frame ◽  
Building Structures ◽  
Base Shear ◽  
Concrete Frames ◽  
Infill Wall ◽  
Infill Walls ◽  
Rc Frames ◽  
Short Beam

This paper presents the results of the experimental and analytical investigations conducted on four 0.8 scale 2-story one bay ductile reinforced concrete frames with infill nonstructural walls subjected to cyclically increasing loads. The material properties and the member sizes of beams and columns in the four RC frame specimens are identical, but with different types of infill nonstructural wall. These four frames are the pure frame, frame with short column, frame with short beam and frame with wing walls. The four RC frame specimens were designed and constructed according to the general prototype building structures in Taiwan. Test results indicate that the ductility behavior of the frames with infill wall is similar to those of the pure frame. The ultimate base shear strength of the frames with infill walls is higher than those of the pure frame. Analytical results show that the proposed simplified multi-linear beam-column element implemented in a general purpose structural analysis program can accurately simulate the cyclic responses of the RC frame specimen incorporating the elastic flexural stiffness computations suggested by the model building codes.

scholarly journals Effects of Single and Multi Openings in Brick Infills on the Seismic Response of Infilled RC Frames

2018 ◽  
Vol 215 ◽  
pp. 01036
Author(s):  
Maidiawati ◽  
Jafril Tanjung ◽  
Hamdeni Medriosa ◽  
Yulia Hayati
Keyword(s):  
Seismic Response ◽  
Dissipated Energy ◽  
Rc Frame ◽  
Infilled Frames ◽  
Masonry Infill ◽  
Infilled Frame ◽  
Rc Frames ◽  
Central Opening ◽  
Lateral Strength ◽  
Infilled Rc Frames

Many researchers have performed a lot of studies of the seismic behavior reinforced concrete (RC) frame with masonry infill. They found that masonry infill affects the lateral strength, stiffness and ductility performance of the RC frame structures. However, when openings appeared in the panel infill for door and windows, the responses of the overall structure are entirely changed. The primary purpose of this study is to experimentally investigate the behavior of brick infilled RC frames possessing single opening and two openings. Four specimens of 1/4-scale single bay RC frames with brick infills were made that were one bare frame, one frame with full infill and two frames with infills having a central opening and two openings with the opening ratio of 25%. The specimens were tested under lateral reversed cyclic loads. Consequently, different responses of failure mechanism, lateral strength, stiffness and energy dissipated were observed among the specimens. The brick full infill failed in shear with propagation cracks in central part of the panel, but in the case of the infills with single and two openings, the cracks were dominated at the corners of the openings. The in-plane strength, stiffness and dissipated energy of infilled frames decreased when openings appeared in the panel. However, the seismic performance of brick infilled frame with the opening of 25% of panel area is better than those of bare frame. The brick infilled frames with a central opening and two openings are similar in lateral strength and dissipated energy. It seems that area and position of the openings control the seismic response to the overall infilled frame structure of the openings

Effects of Modeling Staircases on Seismic Responses of Concrete Frames

2017 ◽  
Vol 23 ◽  
pp. 72-87 ◽  
Author(s):  
Majid Ghaderi Garakani ◽  
Saeed Mahjoubi ◽  
Shervin Maleki
Keyword(s):  
Frame Structures ◽  
Second Step ◽  
Seismic Loads ◽  
Rc Frame ◽  
Concrete Frames ◽  
Strong Earthquakes ◽  
Shell Elements ◽  
Rc Frames ◽  
Rc Frame Structures ◽  
Bracing System

Staircases in reinforced concrete (RC) frame structures have suffered severe damages in past earthquakes, despite being regarded as the main means of egress during emergencies. To make sure that staircases perform as safe passages in strong earthquakes, the performance of RC stair structures should be scrutinized under major earthquakes. In this research at first, staircases were simulated as shell elements in RC frames and analyzed under gravity loads in order to find the maximum forces and moments. In the second step, the influence of staircases on the structural behavior of RC frame structures under seismic loads was studied. The results showed that stairs act as a K-type bracing system. Furthermore, a parametric study was carried out and relations for calculating force and moment in stairs slabs that had been determined under gravity loads, were modified. In addition, affected areas of structure interacting with the stairs in an earthquake were distinguished.

scholarly journals Performance of RC frames in 26.11.2019. Albania earthquake: Effects of irregularities and detailing

2021 ◽  
Vol 64 (3) ◽  
pp. 207-213
Author(s):  
Ivan Milićević ◽  
Marko Marinković ◽  
Nikola Blagojević ◽  
Svetlana Nikolić-Brzev
Keyword(s):  
Earthquake Engineering ◽  
Rc Frame ◽  
Flexible Systems ◽  
Rc Frames ◽  
Seismic Force ◽  
Frame Buildings ◽  
Frame System ◽  
Rc Frame Buildings ◽  
Earthquake Effects ◽  
Global And Local

The collapse and damage of large number of buildings during the November 26, 2019 (Mw 6,4) Albania earthquake caused 51 fatalities and injuries to at least 910 people. Most of collapsed or heavily damaged buildings were RC frame buildings. Although RC frame system is considered as very ductile seismic force-resisting system, its behaviour during earthquake highly depends on: (1) regularity in plan and elevation, and (2) global and local ductility. Based on the authors' visit to the earthquake-affected area on behalf of the Serbian Association of Earthquake Engineering and observations of collapsed and damaged buildings, it was concluded that among main reasons for underperformance of these flexible systems were inadequate analysis of interaction between infill walls and RC frames and reinforcement detailing of RC members.

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