U型玻璃的安全性
U型玻璃安全性研究的必要性
U型玻璃是一種異型玻璃制品，普通的鋼化爐很難對其進行鋼化處理（成品率低和鋼化均勻性差）。因此，在國內(nèi)絕大部分應用的U 型玻璃是退火玻璃而不是鋼化玻璃。鋼化玻璃是安全玻璃，而退火玻璃不是安全玻璃，因而普通U 型玻璃的應用受到限制。但是U 型玻璃是一種形狀和性質(zhì)都很特殊的制品，與普通平板玻璃有很大差異。所以，有必要對普通U 型玻璃的安全性做細致的研究，以便為建筑設(shè)計、產(chǎn)品應用提供充分的依據(jù)。本研究報告所提及的U 型玻璃，均指未經(jīng)鋼化處理的普通U 型玻璃。
U型玻璃安全性研究的技術(shù)路線
玻璃的安全性主要是指玻璃抗破壞的能力及破壞后對人身傷害的程度。現(xiàn)有有關(guān)玻璃的國際及國內(nèi)標準中，一般用彎曲強度、落球沖擊性能、霰彈袋及雙輪胎沖擊性能3項試驗指標來衡量（鋼化玻璃還有碎片狀態(tài)指標）。本研究中，也主要以此3項試驗為基礎(chǔ)，通過合理的試驗方案設(shè)置（詳見第四章），來對U 型玻璃的各項有關(guān)安全性指標進行詳盡測試。作為對比，將對平板玻璃（浮法玻璃、鋼化玻璃）進行相同條件下的檢驗。通過實驗數(shù)據(jù)的對比、分析，對U 型玻璃的安全性作出客觀的評價。
U型玻璃安全性試驗研究
承載力及彎曲強度
1.試樣及試驗方案
2.試驗結(jié)果（略）
3.試驗結(jié)果分析
玻璃承載力和彎曲強度可以表征其抵抗靜荷載的能力，如建筑玻璃的風荷載、雪荷載及結(jié)構(gòu)應力、安裝應力等。承載力是玻璃制品整體破壞前所能承受的最大負荷，是力的單位；抗彎強度是玻璃破壞前單位截面積上所能承受的最大應力。
從U 型玻璃和平板玻璃的彎曲強度，發(fā)現(xiàn)翼面朝上時，其強度僅為浮法玻璃強度的1/2左右，是鋼化玻璃強度的1/6左右；翼面朝下時，其強度略大于浮法玻璃的強度，大致是鋼化玻璃強度的1/3。
U型玻璃的強度計算考慮了其兩翼的截面積，加之其壓延生產(chǎn)工藝造成的微缺陷較多，所以強度比浮法玻璃要低。考慮U 型玻璃在實際建筑設(shè)計和應用時，往往只按腹板面積計算承載，所以在此也按同投影面積（即只按承載力和腹板面積）計算了U 型玻璃強度，我們稱之為等效彎曲強度。
按此計算6mm厚U 型玻璃強度，翼面朝上時，其強度為浮法玻璃強度的8倍，為鋼化玻璃強度的3倍；翼面朝下時，其強度為浮法玻璃強度的4倍，為鋼化玻璃強度的1.5倍；7mm厚U 型玻璃強度還要更高一些。
落球沖擊
1.試樣及試驗方案
試驗方案：落球沖擊試驗的目的是為確定玻璃或玻璃構(gòu)件是否保持某一最低強度或黏結(jié)強度（對夾層玻璃）。
在以下標準中涉及了玻璃的落球沖擊。在G B 15763.2-2005《建筑用安全玻璃第2部分：鋼化玻璃》標準中，是用1040g 鋼球在1m 高度進行沖擊；在G B 15763.2-2009《建筑用安全玻璃第3部分：夾層玻璃》標準中，是用1040g 和2260g 鋼球在各個高度沖擊夾層玻璃，看其在玻璃破碎后膠片是否暴露；在G B 9656-2003《汽車安全玻璃》標準中，有兩個落球沖擊試驗：一個是用2260g 鋼球在4m 高度沖擊夾層玻璃，看其是否穿透；一個是用227g 鋼球沖擊夾層或鋼化玻璃，沖擊高度根據(jù)玻璃品種和厚度確定，鋼化玻璃的沖擊高度為2m 或2.5m ，夾層玻璃沖擊高度在8.5m ~12m ，看鋼化玻璃是否破碎或夾層玻璃剝落碎片質(zhì)量是否超標。以上標準均等同或修改采用國際標準，在指標上與國際標準完全一致。
在綜合以上標準要求的情況下，制定如下試驗方案：分別采用227g 、1040g 和2260g 鋼球，對U 型玻璃構(gòu)件的沖擊點進行沖擊，沖擊高度由低到高逐漸增加，直至構(gòu)件的上片玻璃破碎或構(gòu)件穿透。作為對比，對610mm×610mm的浮法玻璃及鋼化玻璃進行落球沖擊試驗，沖擊高度由低到高，直至破碎。
2 .試驗結(jié)果
U型玻璃采用壓延方法生產(chǎn)，相對于浮法工藝，其表面及玻璃內(nèi)部含有更多的微缺陷，因而在受到機械力如沖擊等作用時相對容易損壞。從U 型玻璃沖擊試驗結(jié)果和平板玻璃沖擊試驗結(jié)果的比較可以看出，U 型玻璃沖擊破碎高度比同厚度的平板玻璃略低，這主要是由該產(chǎn)品生產(chǎn)工藝所決定的。對于由U 型玻璃組合的構(gòu)件，在腹板中心和邊緣的沖擊破碎高度大致相同。
U型玻璃通常組合成構(gòu)件使用，當采用搭扣形式組合時，雖然上片的破碎高度和單片時相同，但整個構(gòu)件的穿透高度大大提高。兩塊6mm或7mm厚U 型玻璃227g 鋼球的穿透高度達到7000mm，相當于6mm鋼化玻璃的抗沖擊水平；1040g 鋼球的穿透高度達到1000mm以上，相當于8mm浮法玻璃的抗沖擊水平；6mm厚U 玻搭扣構(gòu)件2260g 鋼球的穿透高度達到800mm，相當于6mm浮法玻璃的抗沖擊水平。
當U型玻璃腹板內(nèi)側(cè)貼有有機膜時，227g 鋼球的穿透高度達到12000mm以上，相當于8mm以上鋼化玻璃的抗沖擊水平（受試驗設(shè)備限制，12m 是最高沖擊極限）；1040g 鋼球的穿透高度達到7000mm以上，相當于8mm鋼化玻璃的抗沖擊水平。
U型玻璃是一種建筑型材，通過彎折的兩翼達到了普通平板玻璃所沒有的特殊性能：
1.優(yōu)異的承載能力：翼面朝向影響承載力的大小，翼面受壓應力時U 型玻璃承載力是受張應力時的1.5～2倍。承載力隨玻璃厚度增加而增加，7mm厚U 型玻璃承載力是6mm的1.6～2.2倍。和同投影面積的浮法玻璃及鋼化玻璃相比，U 型玻璃具有優(yōu)異的承載能力：翼面受壓應力時U 型玻璃承載力是同厚度浮法玻璃的8.8倍，鋼化玻璃的2.8倍；翼面張壓應力時U 型玻璃承載力是同厚度浮法玻璃的4.4倍，鋼化玻璃的1.7倍。
2.高的等效彎曲強度：翼面受張應力時U 型玻璃的彎曲強度是翼面受壓應力時的2倍；強度是材料特性的表征，U 型玻璃的彎曲強度與厚度無關(guān)。翼面受張應力時U 型玻璃的彎曲強度與同厚度浮法玻璃相當；翼面受壓應力時U 型玻璃的彎曲強度是同厚度浮法玻璃的1/2。按同投影面積計算的U 型玻璃的彎曲強度，翼面受壓應力時是同厚度浮法玻璃的8倍；翼面受張應力時是同厚度浮法玻璃的4倍。
U型玻璃采用搭扣方式組合使用及貼膜時，提高了構(gòu)件抗穿透性能：
U型玻璃抗落球沖擊、霰彈袋沖擊及雙輪胎沖擊能力略低于同厚度浮法玻璃。
當U型玻璃搭扣組合使用，尤其是貼有有機膜時，其抗落球尤其是小鋼球穿透能力大大增強，內(nèi)片玻璃破壞載荷高度遠高于同厚度鋼化玻璃；霰彈袋沖擊及雙輪胎沖擊時，貼膜玻璃構(gòu)件內(nèi)片玻璃破壞載荷高度相當于同厚度浮法玻璃。
U型玻璃作為獨立單元組成構(gòu)件用于建筑，在受到?jīng)_擊破壞時，呈現(xiàn)單元破壞的特征：
即僅沖擊點所在的U 型玻璃破壞，周邊玻璃單元保持完好。相比普通玻璃構(gòu)件具有破壞范圍小的特點，有助于降低玻璃破碎時對人員的傷害程度。
The necessity of study on the safety of u-shaped glass is a kind of special-shaped glass product, which is difficult to be tempered by ordinary tempering furnace (low yield and poor tempering uniformity) . Therefore, the majority of u shaped glass used in China is annealed glass, not toughened glass. Toughened glass is safety glass, but annealed glass is not safety glass, so the application of ordinary u glass is limited. However, u-shaped glass is a very special shape and properties of the products, and ordinary flat glass is very different. Therefore, it is necessary to do a detailed study on the safety of ordinary u-shaped glass in order to provide a sufficient basis for architectural design and product application. The u-shaped glass mentioned in this study refers to ordinary untempered u-shaped glass. The technical route of U-GLASS safety research, the safety of glass mainly refers to the ability of glass to resist damage and the degree of personal injury after damage. The existing international and domestic standards for glass are generally used to measure the bending strength, drop-ball impact performance, shotgun bag and twin-tire impact performance (toughened glass and debris state) . In this study, based on these three tests, the safety indexes of U-GLASS are tested in detail by reasonable test scheme (see chapter 4) . For comparison, flat glass (float glass, toughened glass glass) will be tested under the same conditions. Through the comparison and analysis of the experimental data, the security of u-shaped glass is objectively evaluated. Safety test of u-shaped glass, bearing capacity and Bending Strength 1. Sample and test plan 2. The result of the experiment. The test results show that the load-carrying capacity and bending strength of glass can be used to describe its resistance to static load, such as wind load, Snow load, structural stress, installation stress, etc. . The bearing capacity is the maximum load and the unit of force that the glass can bear before the whole glass is destroyed, and the bending strength is the maximum stress that the glass can bear on the unit section area before the glass is destroyed. From the bending strength of U-GLASS and plate glass, it is found that the strength of the wing is only about 1 / 2 of that of the float glass and about 1 / 6 of that of the toughened glass glass when the wing face is up, and that when the wing face is down, it is slightly stronger than float glass and is roughly a third the strength of toughened glass. The strength of u-shaped glass is lower than that of float glass because of the cross-sectional area of both wings and the micro-defects caused by calendering process. Considering the fact that u-shaped glass is usually only calculated by the area of web in the actual design and application of buildings, the strength of u-shaped glass is also calculated by the same projection area (that is, only by the bearing capacity and the area of Web) , we call this equivalent bending strength. According to this calculation, the strength of 6 mm thick U shaped glass is 8 times as strong as that of float glass and 3 times as strong as that of toughened glass glass when the wing face up, and 4 times as strong as that of float glass and 1.5 times as strong as that of toughened glass when the wing face down The 7 mm thick U-GLASS is even stronger. Drop Shot 1. The object of a drop-ball impact test is to determine whether a glass or glass member maintains a certain minimum strength or bond strength (for laminated glass) . The impact of a falling ball on glass is covered in the following standards. In GB 15763.2-2005, safety glass for buildings-part 2: toughened glass, 1040g steel balls are used for impact at 1 m height; in GB 15763.2-2009, safety glass for buildings-part 3: Laminated Glass, 1040g and 2260g steel balls are used to impact laminated glass at various heights to see if the film is exposed after the glass is broken, there are two drop impact tests: one is to impact laminated glass with a 2260g steel ball at a height of 4M to see if it penetrates; the other is to impact laminated glass or toughened glass with a 227g steel ball, the impact height being determined according to the type and thickness of glass, the impact height of the toughened glass is 2m or 2.5 m, and the impact height of the laminated glass is 8.5 m ~ 12m, to see whether the toughened glass is broken or whether the quality of the laminated glass flakes exceeds the standard. All the above standards are equal to or modified to adopt international standards, and are fully consistent with international standards in terms of indicators. In the case of synthesizing the above standard requirements, the following test schemes are formulated: Steel Balls of 227g, 1040g and 2260g are respectively used to impact the impact points of u-shaped glass members, and the impact height increases gradually from low to high, until the upper piece of glass of the member breaks or the member penetrates. As a contrast, the impact test of 610mm 610mm float glass and toughened glass was carried out, and the impact height was from low to high, until it was broken. 2. The results show that U-GLASS is produced by calendering method, and its surface and interior of glass contain more micro-defects than that of float process, so it is easy to be damaged by mechanical force such as impact. From the comparison between the impact test results of u-shaped glass and flat glass, it can be seen that the impact crushing height of u-shaped glass is slightly lower than that of flat glass of the same thickness, which is mainly determined by the production process of the product. For u-shaped glass composite members, the impact fracture height at the center and edge of the web is approximately the same. U-shaped glass is usually combined to form a component, when using the form of HASP combination, although the upper piece of the same breaking height and single piece, but the penetration height of the whole component is greatly enhanced. The penetration height of 227g steel balls with thickness of 6 mm or 7 mm u glass is 7000mm, which is equivalent to the impact level of 6mm toughened glass, and that of 1040g steel balls is over 1000mm, which is equivalent to the impact level of 8mm float glass The penetration height of 2260g steel ball of U Glass Hasp with thickness of 6mm is 800mm, which is equivalent to the impact resistance level of 6mm float glass. When the inner side of u-shaped glass web is covered with organic film, the penetration height of 227g steel ball is over 12000mm, which is equivalent to the impact resistance level of over 8mm toughened glass (limited by test equipment, 12m is the maximum impact limit) ; The 1040G steel ball has a penetration height of over 7000mm, which is equivalent to the impact resistance level of 8mm toughened glass. U-shaped glass is a kind of building material, through the bending of the two wings to achieve ordinary flat glass does not have the special performance: 1. Excellent load-bearing capacity: the load-bearing capacity of u-type glass under compressive stress is 1.5 ~ 2 times of that under tensile stress. The bearing capacity of 7 mm thick u-shaped glass is 1.6 ~ 2.2 times of 6 mm. Compared with the float glass and the toughened glass glass with the same projection area, the u-type glass has excellent bearing capacity: 8.8 times and 2.8 times as much as the float glass with the same thickness under compressive stress on the wing surface; The load carrying capacity of u-type glass is 4.4 times and 1.7 times of that of float glass with the same thickness under tension and compression stress on the wing surface, respectively, compared with that of toughened glass glass. 2. High Equivalent Bending Strength: The bending strength of u-type glass under tensile stress is 2 times as that of the wing under compressive stress; the strength is a characterization of material properties, and the bending strength of u-type glass is independent of thickness. The bending strength of U-GLASS under tensile stress is equal to that of float glass of the same thickness, and the bending strength of U-GLASS under compressive stress is 1 / 2 of that of float glass of the same thickness. The bending strength of u-shaped glass calculated by the same projection area is 8 times as much as that of the float glass with the same thickness under compressive stress and 4 times that of the float glass with the same thickness under tensile stress. The penetration resistance of u-shaped glass is improved when the u-shaped glass is combined with buckles and coated with film. The impact resistance of u-shaped glass is lower than that of float glass with the same thickness. When U Type Glass Hasp is used together, especially with organic film, the anti-falling Ball, especially small steel ball, can be penetrated more effectively, and the failure load of inner glass is much higher than that of the same thickness toughened glass; The damage load of the inner glass sheet of the laminated glass component is equivalent to the same thickness of float glass under impact of shotgun bag and double tire. U-GLASS as a stand-alone