本文選題：樁承臺節(jié)點　切入點：擬靜力試驗　出處：《清華大學》2015年碩士論文　論文類型：學位論文

【摘要】：相比灌注樁,預制樁有著樁身質量高,經(jīng)濟環(huán)保等優(yōu)點,隨著建筑工業(yè)化進程推進,預制樁越來越多地被推廣使用。然而,國內預制樁抗震理論研究仍有欠缺,使其在高抗震烈度地區(qū)應用受限,這方面研究急需補充。在預制樁抗震性能研究中,樁-承臺后澆節(jié)點尤為關鍵,國外相關研究多采用理論分析、試驗研究以及數(shù)值仿真來評估預制樁承臺節(jié)點抗震性能。現(xiàn)階段國內建筑預制樁承臺后澆節(jié)點常采用樁端鋼筋錨固、樁身填芯、樁頂淺嵌固節(jié)點構造形式,這一構造設計意在通過錨固保證抗彎承載力,通過填芯提供截面抗剪及避免局部破壞并保證一定的節(jié)點變形能力。本文首先利用足尺擬靜力試驗,對采用這一構造形式的離心成型高強混凝土空心方樁-承臺節(jié)點進行抗震性能評估,對軸壓水平、加載方向、嵌固深度和樁身配筋率等參數(shù)進行試驗分析。試驗節(jié)點最終破壞形式為2倍樁徑以下的樁身塑性鉸破壞,試驗表明,從抗震設計角度,該構造下空心方樁軸壓比不宜超過0.5,建議工程使用控制軸向荷載上限。本文對采用相同構造方式的復合配筋管樁承臺節(jié)點進行擬靜力試驗研究,研究了軸壓變化、填芯構造、復合配筋等參數(shù)對承壓節(jié)點性能影響,同時評估了抗拔構造節(jié)點性能,另外還設計了一類簡化的半剛性節(jié)點構造形式,并對其進行節(jié)點抗震性能評估。試驗結果表明,該節(jié)點主要破壞形式為樁頭嵌固深度內承臺保護層破壞,嵌固失效后承載力由填芯和錨固提供。這一模式下,承壓節(jié)點表現(xiàn)出了較好的承載力和變形性能,但抗拔節(jié)點則表現(xiàn)出了承載力的突然下降和節(jié)點脆性破壞。建議工程使用保證一定軸壓,并對承臺保護層進行配筋加強。結合空心方樁試驗,說明樁身和承臺性能差異是節(jié)點最終破壞模式的決定性因素,同時軸壓也是重要因素,大軸壓下樁身承擔更多損傷。試驗結果同時還說明,本研究設計的半剛性節(jié)點構造在標準軸壓水平下表現(xiàn)出較好的抗震性能,延性較好,耗能指標優(yōu)異。本文最后利用Abaqus對空心方樁嵌固節(jié)點進行數(shù)值建模,采用預應力場還原了預制樁后澆節(jié)點的施工工藝,利用非線性彈簧模擬錨固鋼筋的粘結滑移。通過和試驗數(shù)據(jù)的比對,論證了模型單調加載結果的可靠性,并且指出了模型不適合往復加載的原因。結合數(shù)值模型單調加載,本文探討了軸壓、填芯和樁身配筋的影響,其中,軸壓對節(jié)點最終破壞模式影響最大,單調加載下填芯摩擦系數(shù)對性能無顯著影響,樁身塑性鉸破壞模式下增加配箍能有效改善節(jié)點力學性能。
[Abstract]:Compared with cast-in-place piles, prefabricated piles have the advantages of high quality, economic and environmental protection, etc. With the development of construction industrialization, prefabricated piles are more and more widely used. However, the theoretical research on earthquake resistance of prefabricated piles in China is still deficient. It is very important to study the seismic behavior of prefabricated piles, especially in post-cast-in-place joints of pile-cap. Experimental research and numerical simulation are used to evaluate the seismic behavior of prefabricated pile cap joints. At present, the post-cast-in-place joints of prefabricated pile caps are usually constructed in the form of reinforcement anchoring at the end of piles, core filling of piles and shallow embedded joints at the top of piles. The purpose of this structural design is to ensure flexural bearing capacity by anchoring, to provide shear resistance of cross-section through core filling, to avoid local damage and to guarantee certain deformation capacity of joints. In this paper, first of all, full-scale quasi-static test is used. The seismic behavior of hollow square pile-cap joints with centrifugally formed high strength concrete with this structure is evaluated, and the axial compression level and loading direction are evaluated. The test results show that the ultimate failure of the test joint is the plastic hinge failure of the pile body under 2 times the diameter of the pile. The test results show that, from the point of view of seismic design, Under this structure, the axial compression ratio of hollow square pile should not exceed 0.5. It is suggested that the upper limit of axial load should be controlled in engineering. In this paper, the pseudostatic test of composite reinforced pipe pile cap joints with the same structure is carried out, and the variation of axial pressure and the core-filling structure are studied. The effects of composite reinforcement and other parameters on the performance of bearing joints are also evaluated. In addition, a simplified structure of semi-rigid joints is designed, and the seismic behavior of joints is evaluated. The main failure form of the joint is the failure of the protective layer of the pile cap in the depth of the embedded pile head, and the bearing capacity after the embedded failure is provided by the core filling and the anchoring. In this mode, the bearing capacity and deformation performance of the bearing joint are better. However, the anti-jointing point shows a sudden drop in bearing capacity and brittle failure of the joints. It is suggested that certain axial compression should be guaranteed in the engineering, and reinforcement of the protective layer of the cap should be strengthened, and combined with the test of hollow square pile, It shows that the difference between pile body and pile cap performance is the decisive factor of the ultimate failure mode of the joint, and axial compression is also an important factor, and the pile body bears more damage under large axial compression. The test results also show that, The semi-rigid joint structure designed in this paper shows good seismic performance, good ductility and excellent energy consumption index at the standard axial compression level. Finally, numerical modeling of hollow square pile embedded joints is carried out by using Abaqus. The prestress field is used to reduce the construction technology of prefabricated post-pouring joint, and the bond-slip of anchor bar is simulated by nonlinear spring. The reliability of the monotonic loading result of the model is proved by comparing with the test data. The reason why the model is not suitable for reciprocating loading is pointed out. Combined with the monotonic loading of numerical model, the effects of axial compression, core filling and pile body reinforcement are discussed in this paper, in which axial compression has the greatest influence on the ultimate failure mode of joints. The friction coefficient of the core under monotonic loading has no significant effect on the performance, and the mechanical properties of the joints can be effectively improved by increasing the hoop under the failure mode of plastic hinge of the pile body.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU473.1

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