Discussion on Design Method of Prestressed Concrete Frame Joints with Spread-Ended Beams

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1 4th International Conferene on Sutainale Energy and Environmental Engineering (ICSEEE 2015) Diuion on Deign Method of Pretreed Conrete Frame Joint with Sread-Ended Beam LIU Qing-wena, LI Wen-Xv, XU Qing-yun, LV Chaod Shool of Civil Engineering and Arhiteture, Nanhang Hangkong Univerity, nanhang , China a qingwenliu@126.om @qq.om @qq.om d @qq.om Keyword: retreed onrete, frame oint, deign method Atrat. Baed on the reviou exerimental and numerial analyi tudie, the deign menthod for retreed onrete frame oint with read-ended eam are rooed aording to home and aroad related deign ode and referene, and the deigned method i verified y tet data. The reult how that the method i feaile and an meet the need of engineering. Thi method an e ued in engineering deign in engineering ratie. Finally, the deign meaure for the eam-olumn oint ore and the read-ended region are reommended. Introdution In the eimi deign of retreed onrete truture, frame truture mut have good dutility. In order to otain etter dutility, a large numer of horizontal tirru mut e in the ore area of frame oint. For retreed onrete frame truture, overly dene tirru will lead to diffiulty in ontrution of retreing tendon through the ore area of oint. Adoting oint with read-ended eam for the deign heme rovide many advantage for ontrution. Reinfored onrete eam-olumn oint i a omliated and imortant memer in frame truture, and take a very imortant role in eimi reitane. Sine the 1960, numerou exerimental and analytial tudie have foued on the ehavior of RC eam-olumn oint ueted to eimi loading and to etalih guideline for deign[1-3]. However, mot of tudie have een onduted on the onventional oint. retreed onrete oint with read-ended eam, whih are widely alied in uilding, are eldom reorted in the literature. For oint with read-ended, retreing tendon do not take a diret ation on the ore area of oint eaue of anhorage and tendon emedded in the haunhed. The otential advantage and aliation of read-ended eam i often ignored due to the lak of undertanding in the erformane of oint under eimi demand. In thi aer, aed on home and aroad deign ode and related referene literature, the deign menthod for retreed onrete frame oint with read-ended eam are rooed aording to my reviou exerimental and numerial analyi tudie. Deign method of oint urrent onrete ode in China In ode for deign of onrete truture (GB )[4] in hina, the eimi hear aaity of frame oint i omoed of two art of onrete trut and horizontal tirru. Aording to GB , the hear earing aaity of the eam olumn oint hould e in aordane with the following roviion. For 9 degree eimi reautionary intenity h a V [0.9η ft h + f Av 0 ] / γ (1) For other ondition The author - Pulihed y Atlanti Pre 288

2 h a V fh + N + f A (2) [1.1 t v ]/ Where γ i the adutment oeffiient of eimi aaity, η i the influene oeffiient of the ontraint of the orthogonal eam, when onrete floor are at-in-lae, the eam-olumn enter line i overla, the width of four ide eam i not le than 1/2 of the olumn width, and the height of the orthogonal diretion i not le than the height of 3/4, η =1.5. For 9 degree eimi reautionary intenity, η =1.25. when not meet the aove ontraint, η =1.0. f t i deign value of tenile trength of onrete. f i tenile trength of teel ar. h i the ro etion height of the oint ore area. i the etion effetive width of the oint ore area. N i the axial fore of the oint. A v i the ro-etional area of tirru in the ore area of the effetive width. h 0 i the effetive height of the eam etion, whih an take the average value of the two ide of the eam. Other deign method in the literature R.ark had done omarative retreed onrete oint tet [5]. Study howed that a eam eimen didn t et u retreing tendon, another eimen et u retreing tendon in the middle of the eam, the eam ize and flexural trength of two eimen were the ame. Although oth had the ame tirru in oint, oviouly eimen with non-retreing tendon detroyed muh eriouer than retreed eimen. In China, Southeat Univerity rofeor Tang JiuRu alo arried out reearh on retreed onrete frame oint. Aording to the tet reult, referring to rofeor Tang JiuRu, Eq.(3) to alulate the hear trength of oint onidering retreing tendon [6]. V = 0.4N = 0.4σ A (3) e Where V i tendon ontriution to the hear trength of oint, Reetively, N i the fore of oint ore region y effetive retreing tendon, σ i the effetive retre, and A i the area of the retreing tendon through oint ore region. For ontriution of retreed tendon to the hear aaity, the reult how that the hear trength of oint hould not take into aount the ontriution of retreing tendon through oint outer region, otherwie overetimate the hear aaity of oint, therefore, A i only the area of retreing tendon through oint ore region. The tre of the onrete i retrained y the omreive tre of the retreing tendon, and the hear trength of onrete i imroved. Aording to the exerimental data, the ontriution of hear trength an e omoed of onrete, retreing tendon and tirru and the exreion i a follow: N h0 a V 0.1 ψ(1 + ) fh + fyah + 0.4N (4) hf e Shear deign method of retreed onrete frame oint with read-ended eam Aording to the reviou exerimental and Numerial analyi tudie [7-8], We an know hear trength of onrete oint onit of three art, namely hear aaity of onrete i V, hear aaity of reinforement i V and effet of retreing fore i V. Shear aaity of onrete and tirru i till in aordane with the urrent tandard alulation formula. For the ake of afety, the enefiial effet of the addition of the axillary to the hear trength of oint i not onidered when alulating the ultimate hear trength of oint. V = (1.1η fh t ηn ) (5) 289

3 h0 a V = fav (6) The ontriution to the hear aaity of oint i known in the reviou exeriment and theoretial analyi. The effetive retre ha little ontriution to the imrovement of the hear trength of the oint. The hear trength of the oint hould e onidered. Eq.(3) i ued to alulate the hear trength of the eam olumn oint. In ummary, the hear trength of the retreed onrete frame oint with read-ended eam an e alulated y Eq.(7): 1 h0 a V [1.1η fh t ηn + fav ] + 0.4N (7) γ where N i the effetive retreing fore of tendon through oint ore region. Comarion of exerimental reult and theoretial reult In order to verify Eq.(7), it an e ued to alulate the hear trength of the retreed onrete frame oint with read-ended eam. In thi aer, we an take three eimen a examle in the exerimental tudie [8]. The model olumn length of 1650 mm. The ditane of the loading oint on the eam end to the olumn etion enter i 1250mm. Column etion ize i 300mm 300mm. Pretreed onrete eam etion ize i 200mm 450mm. Conrete rotetion layer thikne i 25mm. The oint in the ore area of the tirru i φ6@60. We an know the arameter of the eimen and material detail from the literature [8]. Aording to Eq.(7) to hek the oint hear aaity of three eimen. f The earing aaity of the eimi adutment oeffiient γ i 1.0. η = 1, ft = 2.52MPa, = 393.9MPa, = = 300mm, h = 300mm, h 0 = 425mm, a = 25mm, A / = 1.88 We an know: V = (1.1η fh t ηn ) =261.48kN h a V f A For eimen J1 : 0 = v = kn V = V + V = = kN u ol ol ol h0 α M V 1650 P V = V = V = P= 2.367P (425 25) (425 25) 1650 When V =V u,we an edue ultimate aaity of J1 whih i detroy under vertial loading P= 235.6kN. The ultimate aaity of J1 in the exeriment wa kn, more than 235.6kN. For eimen J3 : V = V + V + 0.4N = /3= 604.8kN u M V 1650 P V = V = V = P= 2.367P (425 25) (425 25) 1650 ol ol ol h0 α When V =V u,we an edue ultimate aaity of J1 whih i detroy under vertial loading P= 255.5kN. The ultimate aaity of J1 in the exeriment wa kn, more than 255.5kN. From tirru train urve derived from the exeriment we an know when the eam reahe the yield load and tirru train of the oint ore area alo reahed the yield [8]. v 290

4 In the ame way, it an e verified that J5 alo meet the requirement.therefore, Eq.(7) and tet reult i in good agreement. Suggetion for ontrution meaure In order to revent the lateral ollae of the retreed onrete read-ended eam, the trength of onrete mut e heked. Generally, the thikne of onrete rotetive layer i mall, and the effet of onrete an not e onidered for afety. The horizontal radial load hould e aumed y the additional teel ar, and the area of additional ar hould e et u. The ro-etional area of ingle lim tirru an e alulated a follow: Fl v A v f (8) Where F l i horizontal load, A v1 i etion area of additional teel ar, v i the ditane of additional teel ar, and f i the tenile trength of additional teel ar. In engineering aliation, the etting of additional U haed teel ar i mainly ued in read-ended region. The ontrutional detail i hown in fig.1. The anhorage length of U ar hould e alulated from the enter of the hannel, and the minimum anhorage length of teel ar hould meet the requirement of the deign ode for onrete truture. Conluion Fig.1 Contrutional detail 1. The eifi deign method for retreed onrete frame oint with read-ended eam i rooed aording to the author reviou reult of exerimental and numerial analyi tudie. The deigned method i feaile y omarion of exerimental reult and theoretial reult. 2. The U haed teel ar an e et u in the read-ended region to revent the lateral ollae of the retreed onrete read-ended eam, and the minimum anhorage length of U haed teel ar hould meet the requirement of ode. Aknowledgement Thi work wa finanially uorted y the National Natural Siene Foundation of China( ), the Natural Siene Foundation of Jiangxi (20114BAB206013), Jiangxi Eduation Commiion Siene Foundation (GJJ13510) and Graduate Innovation Fundation of Jiangxi Eduation Commiion (YC2014-S405). Referene [1] Teerahot Suaviriyakit, Amorn Pimanma. Comarative erformane of u-tandard interior reinfored onrete eam olumn onnetion with variou oint reinforing detail. Material and Struture, Volume 41(3), [2] Aaru Biwal, A. Meher Praad, Amlan K. Senguta. Invetigation of Shear Behaviour of Vertial Joint Between Preat Conrete Wall Panel. Advane in Strutural Engineering, Deemer 2014, [3] TANG Jiu-ru. Seimi deign of reinfored onrete frame oint. Naning :South- eat Univerity Pre,1989. in Chinee [4] GB , Code for deign of onrete truture. in Chinee [5] R.Park,and K.J.Thomon,yli Load Tet on Pretreed and Partially Pretreed Conrete Beam-Column Joint. Journal of PCI, 1977,Vol.22(5),

5 [6] TANG Jiu-Ru, PANG Tong-he, HUA Xia-ing. Exerimental tudy on retreed onrete frame oint Journal of Naning Intitute of Tehnology,1988, 18(1), in Chinee [7] LIU Qing-wen, WU Fu-qiang. Finite-element analyi of retreed onrete frame oint with read-ended eam, advane in ivil truture. Vol (2014), [8] LIU Qing-wen, WU Fu-qiang. Charateriti analyi of retreed onrete frame oint with read-ended eam, rogre in indutrial and ivil engineering. Vol (2014),