Figure showing Hong-Kong-Zhuhai-Macau Bridge

This paper examines and evaluates the Hong-Kong-Zhuhai-Macau Bridge in terms of the detailed designs which needs to be considered in the construction of the bridge as well as in the overall maintenance. The Hong-Kong-Zhuhai-Macau Bridge mainly illustrated as indicated in the figure below (Kou et al.  2013 p.99).

 

Figure showing Hong-Kong-Zhuhai-Macau Bridge(Shen  and Luo 2013 p.946).

The following are some of the essential aims of this project (Wu and Peng 2013).

1. To design the detailed drawings for the components used in the construction of the bridge
2. To identify and assess the various winds loads associated with the designed bridge and their effects in the long run

• To establish the various foundations considerations and the materials which should be used in setting the elements

1. To identify and  establish the towel design aspect  employed and the associated aesthetics effects which it has in the long run

The bridged mainly designed is a cable-stayed system with the total estimated length of 1600m. Furthermore, there is a parametric Rambler Channel in the design and this is termed as the main span.  The Rambler Channel has four distinct back spans and these have 80m, 72m, 72m as well as 71m respectively. Subsequently, there are freestanding towers mainly used in the design and these are made of the concrete materials.  The leveling performed using the concrete mainly established  at the +176m whereas the steel-concrete used in the process mainly made from the steel-concrete and this levels estimated to be ranging from the +176m to the overall +295m. The steel-concrete tend to have outer layers mainly made of the stainless steel. Notably, the top layer mainly rose to about 5m and this is glazed using the steel equipment.   The structure not only acts ass the parametric storage facilities for the maintenance equipment but also forms the essential architectural lighting in the bridge system.  Essentially, the stay cables used mainly designed  with two  planes and the critical role of these planes is to  offer the fan arrangement and  this system have deck mainly spaced at the intervals of 18m from the main  span as well as 10m in line with the overall back spans. Stonecutters Bridge is cable-stayed with a total length of 1596m. It has a main span of 1018m across Rambler  Channel  with  four  back  spans  on  each  side,  of  79.75m,  70m,  70m  and  69.25m.  The freestanding  towers  are  in  concrete  up  to  level  +175m  and  steel-concrete  composite  from  level +175m to level +293m  with  the outer steel skin being stainless  steel.  The top 5m is a glazed steel structure, which acts as an architectural lighting feature and provides storage space for maintenance equipment. The 2 planes of stay cables take a modified fan arrangement, anchored at the outer edges of the deck at 18m spacing in the main span and 10m spacing in the back spans  (Zhang, Ma and Zhao 2013.  p. 952). The detailed design diagram for the bridge mainly indicated as shown in the diagram below

Essential aims of the project

First and foremost,  it is important to note that the span for the overall cable-stayed bridge mainly estimated to be 1.2km. this is the length which used in the conducting the detailed design for the overall specifications and works in line with the project. However, various changes are imminently performed and adjusted on the structure basing on the particular challenges that one is likely to report in the work process.  Furthermore, the changes also introduced as a result of the typhoon winds as well as the busy nature of the harbour in the area. The effects of such phenomena mainly depicted to have iminient impacts on the project works a whole.  Also, the design incorporated the considerations on the heavy vehicles.

The essential design considerations mainly used in this project mainly summarised and documented in the overall Design memorandum.  The design criteria used is the Hong Kong manual on the structural design for the Railways and the Highways and this document mainly issued by the HyD. It gives the BS5400 standards and codes which are fundamental to this project work. Furthermore, various operations and computations mainly conducted with the aim of establishing the effects as well as the impacts of the accidental ship impact, wind loads and seismic effects.

Wind loads mainly considered to be the dominated aspect essentially considered in this design work.  In essence,  the bridge mainly considered to be large spatial with high flexible structure. Thus, wind model concept mainly used in computing the dynamic wind effects in line with this project.  This study not only uses the SDM mechanism alone but it integrates the given data with other related wind climate data available in the other sources. Some of the additional sources utilized in the evaluation include turbulence data, on-site wind information as well as terrain model in line with the wind tunnels. Notably, the ocean exposure established to be affected by both the low turbulence and the high velocities of wind. Contrary to the mountainous or urban terrain in which the wind velocities often termed as low but tend to have high velocities in the return.  Thus, the  high   turbulence associated with the wind actions and loads formed the ingredient and the basis for the whole design  in line with the wind loads. The critical  wind velocities  associated with the flutter as well as the deck levels in the  design mainly indicated as shown  in the table below

Wind loads and their impacts

Furthermore, wind loads and the design include the aerodynamic instability check and this was performed based on the stipulated wind velocity thresholds.  Thus, the summary of the whole process decisively given in the table above. From the analysis of the table, it is expected that one minute in line with the wind speed gives the overall speed thresholds at the designated deck level of the bridge. The analysis of the wind essentially conducted empirically.

Subsequently, the empirical study on the stonecutters regarding the risk levels established that there are three core states which one must consider in the limit states.  The crucial three aspects include the 120 years for the elementary SLS return period,  ULS 2400 years as well as  SILS 6000 years.  The three aspects and limits mainly classified as integrity Limit state.  The consideration incorporates that analysis that the bridge must be in a position to stand the earthquakes and thus, should not require maintenance afterwards. Moderate earthquakes occurring should only lead to fewer repairs on the bridge without actually closing it. Finally,  the deformations occurring at the state of severe earthquakes should not lead to any structural integrity loss as well as should not compromise the emergency traffic network in the area. However, the severe earthquakes could lead to the closure of the overall bridge to perform and carry out certain repairs on the bridge system.

The design of the foundations in this project is not only important but also essential.  The designed process used in the foundation sections mainly described as an iterative concept. This is essentially applied with the aim of ensuring that the decisive compatibility mainly achieved in line with the substructure and the makeable superstructure (Hu et al.  2018 p.143).

The foundation type used in the process is the pile and it is designed to accommodate any actions and impacts resulting om the friction loads. The friction loads in the project mainly estimated to result from the soil down darg due to the actions of the reclamations of the ground for long-term settlement.  The bearing pressure for the bridge mainly estimated at approximately 3.1MPa in the moderate sections. For the decomposed rock sections the value mainly estimated at 7.6Mpa (Duan et al. 2018 p.8). Furthermore, considerations often incorporated for ensuring that bored pile design optimum essentially achieved.  The process incorporates the enlargement of the overall bell-out to ensure that there is sufficient bearing capacity  (Yu et al. 2018  p.1045).

Design considerations for seismic effects

Karczmarski et al. (2016) reported that  aesthetic appealing of the bridge mainly achieved by the application of the towel design.   In essence, the parametric freestanding towers developed with metallic materials. The upper sections of the bridge mainly intended to have visual and distinctive features. The circular shapes fundamentally used because of the susceptible nature of the materials.  Additionally, the materials tends to offer shielding effects to the stay cable vibrations as well as vortex shedding in line with the induced vibrations. The vibrations considered in the process often  results  from both the parametric excitations and linear resonance (Hu et al. 2018 p.189).

According to Cai et al. (2018 p.35) it is important to note that the back spans utilized in the process mainly described as monolithic. In essence, the spans have both the stress and the piers which are often caused by the permanent loads upon which they are subjected to in the process. The material selection mainly considered based on the construction sequence adopted in the erection of the various elements in the project (Yan et al.  2016 p.117). Additionally, there is the connection of the stays on the outside deck levels and this mainly carried to reduce the chances of having transverse state bending. Also, consideration mainly was taken in line with the two longitudinal configurations and this process mainly performed by having the box grinders primarily connected at the across the mortars. Subsequently,  conditions also incorporated in line with the torsion combinations depicted for the slagging bending and the longitudinal boxes. Notably,  the ration which is used in the establishment of the bending and torsions effects mainly depend on the available stiffness ratio value. The ration computed in line with the members as well as the overall relative torsion stresses in the system. The design for the Concrete Back Span Design mainly indicated  as illustrated  in the diagram  below

Li et al. (2015) note that the parametric materials used in the designing of the stay cables are the elementary prefabricated PWS. The typical diameters used in the process are  7mm with imminent galvanised wires. Furthermore, the stay cables used has to be extruded in line with the outer sections of the HDPE sheathing. The tensile stress of the wire materials to be used in the construction should at least be 1770 Mpa. Also, the allowable stress in line with the server load should approximately be 770Mpa.  The diameter of the intended stay cable to be used should range from the overall 113mm up to 192mm. The analysis mainly considered from the in sections and towards the outer sections of the back spans. The longest intended cable which can be used in the process should be 54om long as well as weigh approximately 70 tonnes. However, the wind tunnel test in line with the design mainly establishes at the scale of about 1:1.  The essential recommendation of conducting the wind tunnel scale is to come up with the diameters of the stay cables which conforms with drag element coefficient used in the designing the process.   Furthermore,  it is important to investigate and established the surface  profile effects and how they can be used in counteracting the rain-water induced in line with the vibrations.  Also it is important to have the internal dampers mainly installed at the overall deck stay and some situated at the tower anchorages (Li et al. 2015 p.9).

Foundation design and type

Conclusion

In summary, it important to note that this section mainly tackled the detailed design for the bridge. In essence, the bridge  aesthetics forms the essential output and it has to  confirm with the detaailed design consdieration  discussed and computed. Furthermore, the manaul of the highways and the bridges structural for  the Hong-Kong engineering works mainly used in establishing the set criteria  for the overall process. The designed considerations mainly means that it will last and the bridge  will be in a position to accommodate the traffic as well as heavy vehicles while at the same time used  for anchorage.

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