Punching Shear Capacity Analysis of Reinforced Concrete Slab-column Connections Huiyong Guo 1, 2, a * 1, 2,b. , Jinjun Cheng

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1 5t International Conerence on Advanced Engineering Material and Tecnology (AEMT 15) Puncing Sear Capacity Analyi o Reinorced Concrete Slab-column Connection Huiyong Guo 1,, a * 1,,b, Jinjun Ceng 1 Scool o civil Engineering, Congqing Univerity, Congqing 445, P. R. Cina Key Laboratory o New Tecnology or Contruction o Citie in Mountain Area o te Minitry o Education, Congqing 445, Cina a gy67@tom.com, b @qq.com Keyword: reinorcement concrete; lab-column connection; puncing ear perormance; inite element analyi; longitudinal reinorcement ratio. Abtract. In order to olve puncing ear trengt problem o reinorced concrete lab-column connection, an improved puncing ear capacity ormula i preented. Firt, puncing ear capacity o reinorced concrete lab-column connection i analyzed. Ten, a comparion o puncing ear capacity calculation metod i tudied baed on te code: GB51-1, ACI318-8 and EN Te eect o longitudinal reinorcement ratio i analyzed by uing ANSYS inite element otware. Finally, an improved puncing ear capacity ormula i propoed. Te reult indicate tat becaue o te conideration o longitudinal reinorcement ratio, te calculation capacity o te improved puncing ear capacity ormula i more reaonable. Introduction Te lat lab tructure i alo called a lab-column tructure, wic a good economic advantage o eectively reduced torey and can take ull ue o te ouing pace. However, a lat plate i uceptible to puncing ear ailure at it lab column connection. Ti puncing ear ailure igniicantly degrade te overall reitance o te tructure againt gravity load, and tu te tructure may collape. For ti reaon, many tudie ave been perormed to evaluate te puncing ear trengt o lab-column connection. Teodorakopoulo et al [1] preented a imple analytical model to predict te ultimate puncing ear trengt o lab column connection. Te model i baed on te pyical beavior o te connection under load, and i tereore applicable to bot ligtweigt and normal weigt concrete. Coi et al [] perormed a teoretical tudy to invetigate te puncing ear trengt o interior lab-column connection made o teel iber reinorced concrete. Park et al [3] developed a trengt model to predict te direct puncing ear trengt o interior lab-column connection witout ear reinorcement. At lab-column connection damaged by lexural cracking, it wa aumed tat te puncing ear orce wa reited mainly by te compreion zone o te critical ection. Abdulla et al [4] invetigated te eectivene o bonding non-pretreed and pretreed carbon iber reinorced polymer plate to te tenion urace o concrete column-lab connection in bot te erviceability and ultimate limit tate. However, te puncing ear capacity calculation metod o everal national building code are dierent, te puncing ailure mecanim i till not clear yet. Epecially te eect o longitudinal reinorcement ratio in t conidered in our code GB51-1. Tereore, te puncing ear calculation metod o reinorced concrete lab-column connection i tudied in ti paper. Puncing ear capacity Puncing ear perormance o lab around te joint area o reinorced concrete lab-column tructure i very important. Here, we jut conider te puncing ear capacity o reinorced concrete lab witout tirrup or bent-up reinorcement. Dierent puncing ear capacity calculation metod are propoed by tee code[5]: GB51-1 (Cina), ACI318-8 (USA) and EN (Europe). For tee code, te puncing ear capacity ormula can be imply written a V = Cηµ (1) c m 15. Te autor - Publied by Atlanti Pre 44

2 in wic, η= η 1,η ; µ m i critical ection perimeter; i ectional eective eigt. For dierent code, te puncing ear coeicient C and inluence coeicient η are lited in Table 1. Table 1. Calculating parameter o puncing ear capacity witout abdominal reinorcement C i puncing ear coeicient; min ( ) Code C η 1 η GB51-1.7β t ACI318-8 EN '.333λφ c 1/3 Rd, c 1 ck min cp.4 1. α β 4 µ m ( β ) β α.5 + d 4b C k(1 ρ ) v +.1σ in wic, t i concrete tenile trengt, c i concrete compreive trengt, ck i tandard value o concrete compreive trengt, β i inluence coeicient o ectional eigt, β i long ide to ort ide ratio, α i inluence coeicient o column type. In general, te puncing ear capacity i related to many inluencing actor uc a concrete trengt, ape o loading area, longitudinal reinorcement ratio, anti-punc reinorcement placing etc. For dierent code, te main inluencing actor are lited in Table. Table. Main actor in dierent national code inluencing actor GB51-1 ACI318-8 EN concrete trengt ape o loading area Ye Ye No perimeter-eigt ratio Ye Ye No longitudinal reinorcement ratio No No Ye puncing ear cone angle and critical d 45 or 45 or 14 or widt d From Table, it can be een tat te eect o longitudinal reinorcement ratio an t been conidered in te code GB51-1 and code ACI Te code EN conider te eect o longitudinal reinorcement ratio but doen t conider te ape o loading area and perimeter-eigt ratio. Tereore, it i neceary to improve te puncing ear capacity ormula. Calculation analyi A reinorced concrete lab-column connection tructure i conidered in ti paper. In te connection tructure, lab dept =mm, column ize a b= 35mm 35mm, concrete trengt i C3, two-way longitudinal reinorcement coniguration i Φ1@1, reinorcement area per metre i A = 1131mm, teel reinorcement trengt tandard value i 335MPa. ANSYS inite element otware i applied to calculate te puncing ear capacity o reinorced concrete lab-column connection. Te reult o numerical calculation are own in Figure 1 wit te longitudinal reinorcement ratio plotted againt te capacity value. From Figure 1, it can be oberved tat te longitudinal reinorcement ratio doen t ave an eect on puncing ear capacity or te code GB51-1 and ACI In addition, it a a linear cange or te code EN Te puncing ear capacity value o te code GB51-1 i lowet in te tree code. Tereore, te code GB51-1 i more conervative tan te code ACI318-8 and code EN Tu, it i neceary to conider te eect o longitudinal reinorcement ratio. t ' c ck 45

3 Improved puncing ear capacity equation ACI318-8 EN :4 GB51-1 Capacity /kn longitudinal reinorcement ratio Fig. 1. Inluence curve o longitudinal reinorcement ratio In our code GB51-1, te eect o longitudinal reinorcement ratio in t conidered. Tu, te calculation value i too conervative. Troug te comparion o puncing ear capacity ormula o te tree code: GB51-1, ACI318-8 and EN , it can be een tat te puncing ear capacity ould include our main part: correction coeicient, inluence coeicient, concrete trengt, and critical ection area. Tu, Vc = γη µ m () In order to olve te problem tat te puncing ear capacity and te longitudinal reinorcement ratio are uncorrelated in our code GB51-1, te puncing ear capacity equation ould be 13 improved. In te code EN , te puncing ear capacity i proportional to ρ. b Tereore, we can ue te itting equation orm y = ax, in wic, x i reinorcement ratio, y i puncing ear capacity. Te itting reult are own in Figure and Figure 3. Capacity (kn) Data dot Fitting curve 95% conidence interval 95% prediction interval longitudinal reinorcement ratio (%) Fig.. Fitting curve o te equation Te itting value o b i.445, te correlation coeicient i.659. It can be een tat te itting correlation coeicient i cloe to tat o te code EN :4. Tu, te inluence coeicient o longitudinal reinorcement ratio can be given by.445 ξ = (1 ρ L ) (3) In order to avoid te calculation reult o ξ i le tan tat o te old code, it i required tat ξ 1. Tu, te improved puncing ear capacity can be written a V =.7βξ ηµ (4) c t m 46

4 1. α η = min η, η, η =.4 +, η =.5 + (5) β 4µ in wic, { } ξ = ρ.1 L.445 (1 ρl) ρl >.1 m Capacity reidual ditribution (6) Capacity (kn) longitudinal reinorcement ratio (%) Fig. 3. Reidual ditribution Concluion In ti paper, a comparion tudy o puncing ear capacity baed on GB51-1, ACI318-8 and EN , i perormed and an improved puncing ear capacity ormula i preented. By taking into account te analyi reult o te reinorced concrete lab-column connection, te ollowing concluion can be drawn: (1) Te code GB51-1 and ACI318-8 don t conider te eect o longitudinal reinorcement ratio or puncing ear capacity. () Te code EN conider te eect o longitudinal reinorcement ratio but doen t conider te eect o loading area ape and perimeter-eigt ratio. (3) Te improved puncing ear capacity ormula conider not only te eect o longitudinal reinorcement ratio but alo te eect o loading area ape. Tereore, te improved puncing ear capacity ormula i cloer to te act o reinorced concrete lab-column connection. Acknowledgment Project upported by Contruction cience and tecnology Foundation o Congqing (Grant No. 14-5) and upported by te National Natural Science Foundation o Cina (Grant No ). Reerence [1] D.D. Teodorakopoulo, R.N. Swamy. Ultimate puncing ear trengt analyi o lab-column connection, Cement & Concrete Compoite, 4() [] K.K. Coi, M.M.R. Taa, H.G. Park et al. Puncing ear trengt o interior concrete lab-column connection reinorced wit teel iber, Cement & Concrete Compoite, 9(7) [3] H.G. Park, K.K. Coi, L. Cung. Strain-baed trengt model or direct puncing ear o interior lab-column connection, Engineering Structure,, 33(11) [4] A. Abdulla, C.G. Bailey, Z.J. Wu. Tet invetigating te puncing ear o a column-lab connection trengtened wit non-pretreed or pretreed FRP plate, Contruction and Building Material, 48(13)

5 [5] Minitry o ouing and urban-rural development o te People Republic o Cina. Code or deign o concrete tructure (GB51-1), Cina Arcitecture & Building Pre, Beijing, 1. 48