【正文】 stability is ultimately dictated by its affect on the crane’s performance and, in some jurisdictions, by local laws or regulations.Another important consideration is how the crane is secured to the barge. In many places, there is no guidance in the regulations that defines the magnitude of forces that should be used to design the crane securements. We can, however, develop a reasonable design load from the way the barge lists and trims while lifting.Here, we must return to the marine analyses performed to determine the barge’s orientation throughout the lift range of the crane. The slope of the barge deck will result in a horizontal force acting in the plane of the deck that is created by the vertical weight of the crane plus its lifted load and the angle from horizontal of the deck. A design force can be calculated by conservatively ignoring the benefit of friction between the crane and the deck. Developing a design vertical load to the securements will most likely be more subjective. A suitable design load must be determined by empirical means.If the barge crane is to be used in an environment where significant barge motions may occur, dynamic loads must also be considered. Unless the crane is to be used offshore, however, such dynamic loading is unlikely and, as an operational restriction, should be avoided.A fundamental need in the engineering of a barge installation of a mobile crane is the establishment of the load chart. Most crane users intuitively recognise that the normal load charts cannot be used when the crane is mounted on a floating barge. First, the barge will continually move as the crane lifts and swings its load, thereby failing to provide the firm and level support that is required by the normal load chart. Second, the movement of the barge and crane can result in the development of dynamic loads that are not considered in standard crane design.Consider first the outoflevel support. The typical crane operator’s manual requires that be l the crane eveled to within 1% ( degree). A crane mounted on a floating barge will experience continuous changes in trim and list (Figure 8). This usually makes impossible keeping the crane level to within 1%. So we ask the question: How do we develop mobile crane load charts for barge service? The short answer is: We don’t.As previously noted, crane load charts normally cannot be developed by the crane user. The most significant reason for this is that most crane users do not have enough information about the crane to accurately assess its structural and mechanical limitations. Many ponents of the crane will be stressed differently when the crane is out of level. Determination of the crane’s capacity requires detailed knowledge of the strength of all of these ponents.Some crane manufacturers publish barge service load charts for some of their models. If such charts are available, the planning of a barge installation is much more efficient. If such charts are not available, then the manufacturer must be contacted for assistance. Crane and barge bination239。?184。Typically, the contractor will propose a crane and barge bination and perform the necessary analyses to develop a table of data for each lift to be made. This table must include the radius and load for each lift and the angles by which the crane is out of level both sidetoside and front to back. This information is provided to the manufacturer for evaluation. This process will be time consuming, particularly if the first setup is found to be inadequate. A number of iterations may be needed to arrive at a crane and barge bination that is acceptable to the manufacturer for the proposed lifts.There is one last point that must be made regarding barge service load charts. The standard barge charts are based on out of level only. The lifting capacities do not account for any dynamic loads other than those normally considered in crane design. If a bargemounted crane is to be used in exposed waters, wave action may cause barge motions that will create additional dynamic loads. The possibility of dynamic loads may require additional derating. The crane manufacturer should be consulted for guidance.Once the crane is secured on the barge and barge service load charts have been established, the time has e to make the lifts. As with conventional lifting on land, planning is the primary key to success and, at this point, the planning that is unique to marine work has been pleted. A few final points to remember are worth listing here.1. The barge will move. As the load is lifted and swung, the constantly moving centre of gravity will cause the barge’s list and trim to change.2. Movement of the barge will affect the crane’s radius. The crane operator must be aware of what to expect so that he can pensate.3. Movement of the barge may cause the load to sway more than is normal on land. This, too, must be recognised by the operator so that he can adjust the crane’s movements to control the load.4. And last, you can’t do it alone. A safe mobile crane installation on a barge cannot be engineered without the assistance of the crane manufacturer to establish the crane’s rated capacities. This may be as simple as requesting barge service load charts or it may be as plex as asking the manufacturer to develop special charts for one installation.附錄B浮吊的設計與安裝當工作發(fā)生在水面上時起升計算是很復雜的，正如大衛(wèi)Duerr的解釋。重型結構的需求偶爾把起重承包商帶到水邊或更遠處. 這可能是部分建設結構，如橋梁，在水體或一個部分的海洋運輸項目，把貨物從一個容器到另一個?？缭竭@一邊界創(chuàng)建需要一個浮動起重機或井架。雖然現(xiàn)有的海洋重型船只有時被雇用，通常需要進行升降機使用起重機的駁船組成臨時安裝的移動式起重機。正是這種形式的浮吊具有這樣的好處。移動式起重機在駁船上的安裝的設計可分為4個步驟。首先是起重機的選擇。起重機的正常負荷圖表不適用于駁船，因此最初的起重機選擇，必須做一些假定降額。二是選擇駁船。駁船必須強大到足以支持起重機，并必須具備一定程度的穩(wěn)定性，使駁船能正常的浮在水面上。三是設計起重機在駁船上的安裝。這項工作的適用原則，由造船學和結構工程決定。第四是發(fā)展負荷圖表以適用于特定的安裝。起重機選擇的主要問題，從表面上看，這些起重機的選擇看起來和陸基升降機完全一樣。起重機必須在縱向和橫向達到負荷，它必須有能力安全地提升重量。然而，海洋環(huán)境的改變影響這兩個方面。首先，讓我們考慮一下范圍。除了通常的關注熱潮干擾等，駁船本身也影響起重機的性能。駁船起重機幾乎總是解除其負荷上或關閉一些鄰近結構，如另一艘船只或碼頭。因此，有用半徑測量起重機邊緣的駁船（見圖