Improving Behavior of Reinforced Concrete Frames to Resist Progressive Collapse through Steel Bracings

Qian, Kai; Weng, Yun-Hao; Li, Bing

doi:10.1061/(asce)st.1943-541x.0002263

Cited by 48 publications

(10 citation statements)

References 25 publications

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“…The parametric study results indicated that the lower the distance between implantation points is, the higher capacity increment CFR can provide. Besides, the influence of γ r on capacity increment can not be ignored, and γ r was obtained according to the regression of limited test results, thus, more test data are needed to further improve the accuracy of the Equation (9).…”

Section: Analytical Models 41 Analysis Of Load Capacity Increment Of Specimen Icsmentioning

confidence: 99%

“…Traditional strengthening methods are used to prevent progressive collapse of RC frame structure, mainly including prestress strengthening method (Qian et al [3,4]), steel Polymers 2021, 13, 1306 2 of 16 bonding strengthening method [5,6], bracing strengthening method [7][8][9], etc. These methods are effective in strengthening of progressive collapse resistance, but the construction is relatively complicated.…”

Section: Introductionmentioning

confidence: 99%

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

2021

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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.

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Section: Analytical Models 41 Analysis Of Load Capacity Increment Of Specimen Icsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2021

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“…Based on Alternate Load Path method, extensive tests had been carried out in the past decades to understand the capacity of reinforced concrete (RC) frames to resist progressive collapse. These tests could be categorized into three groups: multi-story tests (Yi et al 2008;Sasani et al 2011a;Xiao et al 2015; Qian and Li 2017;Qian et al 2019), single-story beam-column or beam-column-slab subassembly tests (Su et al 2009;Orton et al 2009;Qian and Li 2012a;FarhangVesali et al 2013;Yu and Tan 2013a;Lew et al 2014;Valipour et al 2015a;Qian et al 2016;Ren et al 2016;Peng et al 2017;Qian et al 2018), and single-story beam-column connections tests (Qian and Li 2012b;Yu et al 2014). Yi et al (2008) carried out a 1/3-scaled three-story planar frame test to evaluate the load resisting mechanism of RC frame subjected to the loss of an interior column.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the crushing of masonry infilled walls will not jeopardize the development of TCA of the beam at large deformation stage. Qian et al (2019) also tested another series of five three-story frames to quantify the efficiency of using steel bracings in strengthening RC frames to mitigate progressive collapse. Different configurations of steel bracings were applied.…”

Section: Introductionmentioning

confidence: 99%

Effects of High-Strength Concrete on Progressive Collapse Resistance of Reinforced Concrete Frame

Deng

Liang

et al. 2020

J. Struct. Eng.

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The application of extreme loads such as impact and blast may lead to progressive collapse and the robustness of a structure must be considered in this context. Although extensive studies had been carried out over the past decades to study the load resisting mechanism of reinforced concrete (RC) frames to prevent progressive collapse, the effects of high-strength-concrete (HSC) on progressive collapse resistance capacity is still unclear. Therefore, six tests of RC frames with different span-todepth ratio and concrete strength were conducted in present study. Among them, three are HSC frames and the remaining are normal strength concrete frames. It was found that the use of HSC could further enhance the compressive arch action (CAA) capacity, especially for those with low span-to-depth ratio. On the other hand, HSC can reduce the tensile catenary action (TCA) capacity at large deformation stage, primarily because of higher bond stress between concrete and rebar, leading to earlier fracture of the rebar. The analytical results from the model were compared with the test results. It was found that the refined CAA model could accurately predict the CAA capacity of NSC frames, but not for HSC frames. Moreover, existing model is hard to predict the CAA capacity of the frames with relatively small span-to-depth ratio (less than 7) accurately.

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“…Ma et al [15] tested a 1/3 scaled RC flat plate substructure to assess its behavior under a corner column removal scenario. Qian et al [16] investigated the advantages of using steel braces to strengthen the progressive collapse resistance of RC frames. The steel brace increased the initial stiffness and CAA capacity significantly whereas few benefits for TCA were observed, due to compressive buckling or tensile fracture in braces at large displacement stage.…”

Section: Introductionmentioning

confidence: 99%

Progressive collapse resistance of precast concrete beam-column sub-assemblages with high-performance dry connections

Qian

Liang

et al. 2019

Engineering Structures

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Due to its relatively lower integrity, precast concrete structures are considered to be more vulnerable to progressive collapse than cast-in-place concrete structures. However, to date, majority of existing studies on progressive collapse focused on cast-in-place concrete structures, little attentions were paid to precast concrete structures. Among existing precast concrete structures, unbonded post-tensioning precast concrete structure is one of innovation dry connection structural systems, which no casting at the connections on site. Its excellent seismic performance was recognized by many studies, while studies on its progressive collapse resistance were very few. To fill this knowledge gaps, in this paper, eight half-scaled unbonded post-tensioning precast concrete beam-column sub-assemblages with different connection configurations were tested through pushdown tests to investigate their capacities and resistance mechanisms to prevent progressive collapse. The test results demonstrated various behaviors of beam-column sub-assemblages with different connection types. It was found that, as the longitudinal reinforcements were discontinuous across the beam-column joint region in the beams, flexural action observed in the cast-in-place concrete frames was not mobilized for the specimens with purely unbonded post-tensioning connections. When the specimens installed top-seat angles at the beam-column interfaces, considerable flexural action capacity could be mobilized for load resistance. Moreover, it was found that the failure modes of the specimens are distinctly different to that of conventional reinforced concrete frames or precast concrete frames with cast-in-place joints. The characteristic of compressive arch action and tensile catenary action in tested specimens is quite different to that of conventional reinforced concrete frames.

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Improving Behavior of Reinforced Concrete Frames to Resist Progressive Collapse through Steel Bracings

Cited by 48 publications

References 25 publications

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

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

Effects of High-Strength Concrete on Progressive Collapse Resistance of Reinforced Concrete Frame

Progressive collapse resistance of precast concrete beam-column sub-assemblages with high-performance dry connections

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