本文選題：鋼筋混凝土靶板 + 彈丸��； 參考：《中國科學(xué)技術(shù)大學(xué)》2014年博士論文

【摘要】：鋼筋混凝土廣泛應(yīng)用于國防和民用(如核電廠)工程中,研究鋼筋混凝土結(jié)構(gòu)在彈丸撞擊下的響應(yīng)和破壞,對工程防護設(shè)計和安全評估具有重要的意義。本文的主要目的是預(yù)測鋼筋混凝土靶板在彈丸撞擊發(fā)生不同破壞模式時所需要的臨界能量,并對鋼筋混凝土結(jié)構(gòu)響應(yīng)進行數(shù)值模擬。本文的研究內(nèi)容主要包含以下幾個方面： 基于彈丸侵徹力和鋼筋混凝土靶板沖擊實驗數(shù)據(jù)的基礎(chǔ)上,在統(tǒng)一框架內(nèi)修正了UMIST公式。修正的UMIST公式不僅能適用于平頭彈丸,而且適用于非平頭彈(如尖頭彈、卵形彈和半球形彈等)；不僅能適用于低速撞擊,而且也適用于高速撞擊；不僅適用于低強度混凝土,而且也適用于高強度混凝土。結(jié)果證明修正的公式能在很廣的沖擊條件內(nèi)預(yù)測在彈丸撞擊下鋼筋混凝土靶板產(chǎn)生厚度方向開裂破壞、痂斑破壞和貫穿破壞。 對剛性平頭彈丸撞擊下半無限混凝土靶的深侵徹問題進行研究。通過對實驗現(xiàn)象的觀察,平頭彈丸在侵徹過程中會在彈丸前部產(chǎn)生一個“死區(qū)”。因此,作為一階近似可以將平頭彈丸侵徹半無限混凝土靶的問題看成是錐形彈侵徹半無限混凝土靶的問題來處理。通過采用剛塑性不可壓縮的介質(zhì)模型,利用滑移線理論方法和虛功率原理,得到了混凝土介質(zhì)對平頭彈丸靜阻力部分；再加上由速度效應(yīng)引起的動阻力,得到混凝土介質(zhì)對平頭彈丸的侵徹阻力。根據(jù)所求的混凝土介質(zhì)阻力,代入到彈丸的運動方程,得出彈丸的侵徹深度公式。該公式預(yù)測的彈丸侵徹深度與實驗數(shù)據(jù)吻合得較好。 對鋼筋混凝土板抗沖剪強度問題進行研究。由于現(xiàn)有的鋼筋混凝土板的抗沖剪強度公式中的失效面與真實的失效面并不一致且公式本身并不是無量綱化的,因此現(xiàn)有的公式的適用范圍受到一定的限制。本文提出了一個預(yù)測鋼筋混凝土板在圓柱沖頭壓入荷載作用下發(fā)生沖剪破壞時剪切強度的經(jīng)驗方程,方程中考慮了鋼筋量、鋼筋間距和跨厚比的影響。通過與實驗數(shù)據(jù)比較,以及與現(xiàn)有的經(jīng)驗公式比較,可以看出本文提出的經(jīng)驗公式具有一定的優(yōu)越性。 基于實驗觀察和板厚與彈徑之比的不同,對鋼筋混凝土靶板在平頭彈丸低速撞擊下的厚度方向開裂破壞進行研究。鋼筋混凝土靶板受到平頭彈丸低速沖擊時一般會發(fā)生兩種破壞模式,即直接厚度方向開裂破壞,彈丸無明顯的侵入；彈丸侵入一定深度后的厚度方向開裂破壞。本文首先建立了彈丸沖擊混凝土靶板的侵徹和厚度方向開裂二階段破壞半分析模型,其次利用本文提出的平頭彈丸侵徹混凝土靶板的分析模型得到的侵徹阻力和引入動態(tài)增強因子的鋼筋混凝土靶板的抗沖剪承載力,得到鋼筋混凝土靶板的兩種破壞模式的轉(zhuǎn)化條件(破壞模式圖)。模型預(yù)測與實驗數(shù)據(jù)吻合得較好 利用本實驗室新建立的混凝土動態(tài)本構(gòu)關(guān)系對鋼筋混凝土結(jié)構(gòu)在彈丸撞擊下的響應(yīng)和破壞進行數(shù)值模擬。該混凝土動態(tài)本構(gòu)模型考慮了壓力相關(guān)性、應(yīng)變率效應(yīng)、Lode角效應(yīng)、剪切損傷效應(yīng)和拉伸損傷效應(yīng),通過對平頭彈丸撞擊下的鋼筋混凝土靶板響應(yīng)的數(shù)值模擬,得到的鋼筋混凝土靶板的破壞形貌與實驗觀察非常相近,結(jié)果令人滿意。同時,利用該混凝土動態(tài)本構(gòu)模型對鋼筋混凝土板的厚度、鋼筋間距和尺寸進行數(shù)值模擬研究,得出各因素對鋼筋混凝土靶板受到平頭彈丸撞擊下發(fā)生的破壞模式的影響。由于核電廠中的鋼筋混凝土結(jié)構(gòu)主要為圓柱殼體和球形殼體,利用數(shù)值模擬技術(shù)對殼體結(jié)構(gòu)在平頭彈丸撞擊下產(chǎn)生的破壞情況進行初步研究,結(jié)果表明曲率的存在對鋼筋混凝土結(jié)構(gòu)的抗沖擊能力有利。
[Abstract]:Reinforced concrete is widely used in national defense and civil engineering (such as nuclear power plant), to study the response and damage of reinforced concrete structures under projectile impact. It is of great significance for engineering protection design and safety assessment. The main purpose of this paper is to predict the need for the reinforced concrete target plate in the different failure modes of the projectile impact. The numerical simulation of the response of reinforced concrete structures is carried out.
Based on the experimental data of the impact of the projectile impaction and the impact of the reinforced concrete target plate, the UMIST formula is modified in a unified framework. The modified UMIST formula is not only applicable to flat head projectiles but also for non flat heads (such as pointed projectiles, oval shells and hemispherical projectiles). It is not only applicable to low velocity impact but also for high speed impact. It is not only suitable for low strength concrete, but also suitable for high strength concrete. The results show that the modified formula can predict the thickness of the reinforced concrete target plate under the impact of the projectile in a very wide range of cracking, scab damage and penetration.
The deep penetration problem of a semi infinite concrete target impacted by a rigid flat projectile is studied. Through the observation of the experimental phenomenon, a "dead zone" will be produced in the front of the projectile during the penetration process. Therefore, as a first order approximation, the problem of the penetration of a flat head projectile into a semi infinite coagulant target is considered to be the penetration of a conical projectile. By using the rigid plastic incompressible medium model, by using the theory of slip line theory and the principle of virtual power, the static resistance part of the concrete medium to the flat head projectile is obtained by using the rigid plastic incompressible medium model. The penetration resistance of the concrete medium to the flat head projectile is obtained by the dynamic resistance caused by the velocity effect. The resistance of the condensing medium is replaced by the motion equation of the projectile, and the penetration depth formula of the projectile is obtained. The penetration depth of the projectile predicted by this formula is in good agreement with the experimental data.
In this paper, the problem of the shear strength of reinforced concrete slab is studied. Because the failure surface in the formula of the existing RC plate is not consistent with the actual failure surface and the formula itself is not dimensionless, the applicable scope of the existing formula is limited. In this paper, a prediction of reinforcement coagulation is proposed. The empirical equation of the shear strength of the soil plate under the action of the pressure of the cylindrical punch under the impact of the punching shear is taken into account. The effect of the amount of steel, the spacing of the steel bar and the ratio of the thickness to the thickness is considered. By comparing with the experimental data and comparing with the existing empirical formulas, it can be seen that the empirical formula presented in this paper has some advantages.
Based on the experimental observation and the difference between the thickness of the plate and the diameter of the projectile, the cracking and failure of the reinforced concrete target plate under the low velocity impact of a flat projectile is studied. In the case of the low velocity impact of the flat head projectile, two types of failure modes will occur, that is, the direct thickness direction cracking and the failure of the projectile; the projectile is not intruded. In this paper, the two stage failure semi analysis model of the penetration and thickness direction cracking of the projectile impact concrete target plate is first established. Secondly, the penetration resistance of the projectile penetrating the concrete target plate and the reinforcement coagulation with dynamic enhancement factor are obtained by using the analysis model of the flat head projectile penetrating the concrete target. The resistance to the punching shear capacity of the target plate is obtained by the two failure modes of the reinforced concrete target plate (failure mode diagram). The model prediction is in good agreement with the experimental data.
A numerical simulation of the response and damage of reinforced concrete structures under projectile impact is carried out by using the new dynamic constitutive relation of concrete in our laboratory. The dynamic constitutive model of the concrete is taken into consideration of pressure correlation, strain rate effect, Lode angle effect, shear damage effect and tensile damage effect, through the impact of steel on the flat head projectile. The numerical simulation of the response of the reinforced concrete target plate is very close to the experimental observation, and the results are satisfactory. At the same time, the concrete dynamic constitutive model is used to simulate the thickness of the reinforced concrete slab, the distance and size of the steel bar, and the factors are obtained for the target plate of the reinforced concrete. The effect of the failure mode of a flat head projectile under impact. The reinforced concrete structure in the nuclear power plant is mainly a cylindrical shell and a spherical shell. The damage of the shell structure under the impact of a flat projectile is preliminarily studied by numerical simulation. The results show the impact of the existence of the ratio of curvature to the reinforced concrete structure. Ability is good.

【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU375;TM623

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本文編號：1867598