What is the Advantage and Disadvantage of Xindian Construction

1、Overview of categories of maintenance hangars and space frames

Maintenance hangars are generally divided into wide-body machine hangars and narrow-body machine hangars in terms of service objects ; in terms of the number of service objects, they are generally divided into single-position hangars, double-position hangars and multi-position hangars ; The layout of the hall and maintenance auxiliary rooms is generally divided into surround type and front-to-back type; from the structural point of view, the general maintenance hangar column adopts the column form, the maintenance hangar roof adopts a spherical space frame structure, and the maintenance hangar door head A local truss structure is adopted.

The main limitation affecting the selection of the maintenance hangar lifting scheme is the span and depth of the maintenance hangar itself. Generally, the span ranges from 70 to 150m, and the depth is generally controlled at 60 to 90m ; the height of the space frame is generally determined by the calculation of the structural design after being determined by the first two, and the common ones are single-layer space frame or double-layer space frame. The lifting height of the space frame is generally between 24 and 35m.

2、Common lifting methods for maintenance hangar space frames

According to the different spans and depths of maintenance hangar space frames, different construction conditions, differences in construction quality and cost factors, generally the main hangar space frame lifting schemes include lifting and jacking; different lifting methods are considered The support carrier can be divided into two types: in-situ lifting using the original structure and new point lifting of newly built lattice columns.

2.1、The in-situ hoisting technology of the maintenance hangar space frame The core of the in-situ hoisting technology is to use the originally designed structural column, arrange the hoisting oil pump on the top of the structural column, and synchronously lift the ground-assembled space frame to the top of the structural column through multi-stranded steel cables Design elevation. In this construction process, most of the force of the lifting space frame is borne by the main structure columns, which has great requirements on the main structure itself. The program has been practiced in the construction of the space frame structure of the maintenance hangar of Wuhan Eastern Airlines, and has great reference value in terms of overall project economy.

2.2、Upgrading technology for new points in the maintenance hangar

The core of Xindian’s lifting technology is to build a number of lattice columns slightly higher than the structural columns in the hangar hall according to the calculation, and install a lifting oil pump above the lattice columns, and synchronously lift the space frame assembled on the ground through multi-stranded steel cables. to the design level. During this process, the force of the space frame itself falls entirely on the newly-built lattice columns, without any impact on the original structural system.

This scheme has been successfully practiced in the construction of the space frame structure of the new hangar of Beijing Eastern Airlines, and has accumulated a lot of experience.

2.3、Hangar space frame lifting technology

The core of the space frame lifting technology is to build multiple jacking nodes in the hangar hall according to the calculation, and further subdivide the one-time space frame lifting according to the lattice column modulus, and carry out through multiple lifting rounds: jack “jacking “Liter” – add “standard section” – oil return climbing jack of pumping station – after fixing the force parts of the jack, raise the maintenance hangar space frame to the target design elevation.

This scheme has been successfully practiced in the construction of the maintenance hangar space frame structure of China Eastern Airlines in Qingdao New Airport, and has accumulated a lot of experience.

3、Decision-making analysis of space frame lifting methods

3.1、Conditions and advantages and disadvantages analysis of three space frame lifting schemes

(1) Conditions and advantages and disadvantages analysis of the in-situ lifting scheme. Since the in-situ lifting scheme arranges the oil pump and the lifting device on the original structural column, the reserved load requirements for the structural column are much higher than the normal working conditions of the column. At the same time, in order to facilitate the construction and later repair welding of the space frame, the lifting point is generally cantilevered at a distance of 1~2m outside the structural column, and the force on the column is eccentrically compressed. Therefore, in addition to recalculating the compressive load during structural design, a special recalculation or reservation should be made for the bending and shearing capacity of the column (especially the middle part of the column).

In addition, due to the layout of the original structural system and the load limit of the construction equipment, the in-situ lifting scheme has certain restrictions on the lifting of the large-span two-position or even three-position wide-body machine hangar space frame. Lifting lattice columns are added in the centralized area or the hangar door area to assist in the lifting.

Compared with the other two lifting schemes, economy is the biggest advantage of the in-situ lifting scheme. This scheme can maximize the use of the original structural system without the need for new lattice columns or jacking columns and the lower foundation and cast-in-situ piles, which makes this scheme have a greater advantage in cost sharing.

The second is to improve quality control. The in-situ lifting is carried out synchronously through the computer and the mechanical oil pump after the first leveling of the hangar structural column top after the first installation. Therefore, the construction quality is less subject to human interference, and the construction quality is more reliable.

Relatively speaking, the in-situ lifting scheme has higher requirements on the vertical accuracy of the original structural column. The reason is that when the entire structural system is stressed, the structural column is deformed under force, and the elastic deformation will further aggravate its eccentric compression, thereby further aggravating the overall risk to the original structural system. In other words, in-situ lifting has relatively high requirements for the unit that compiles the construction plan and the unit that designed the original structure. On the other hand, the in-situ lifting scheme requires that the construction of the original structural column be completed and the concrete curing be completed before construction. This will bring more organizational requirements to the construction process and construction schedule.  

The acceptable thermal comfort range for predicted mean vote (PMV) from the ASHRAE 55-2010 is between −0.85 and +0.85 [ 35 ]. Further, the ASHRAE has developed an industry standard, which is known as the Thermal Environmental Conditions for Human Occupancy/ASHRAE Standard 55-2017. PMV and PPD models are the main thermal comfort modules used by ASHRAE Standard 55-2010, which are also adopted by Comité European de Normalization (CEN) and by International Standardization Organization (ISO) standards [ 34 ].

Above all, Jin et al. [ 30 ] remarked that in order to improve user comfort, PMV is the most widely used model and was developed by Fanger in the 1970s through expensive laboratory experiments [ 31 ]. The PMV model is the basis of the International Organization for Standardization (ISO) 7730 standard, which was available in 1994 and 2005 versions [ 32 33 ]. A personal comfort model is in response to individual thermal comfort, which comments or interprets the comfort level based on the person’s surrounding environment. In detail, there are six variables in defining the PMV thermal comfort, namely air temperature, relative air velocity, mean radiant temperature, mean air humidity, clothing insulation, and metabolic rate. Albatayneh et al. [ 34 ] summarized that the first four of these variables can be obtained through measurement sensors; and the remaining two variables of metabolic rate and clothing insulation are dependent on individual users: ISO 9920 (clothing), ISO 8996 (metabolic rate), and ISO 7726 (instruments and methods) [ 32 ]. The PMV is established using heat balance principles and data gathered in a controlled climate environment under steady-state conditions. The PMV index predicts the mean response of the general public, as outlined by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) thermal sensation scale, as shown in Table 1

The analyzed items, formulated based on the existing buildings, were sunlight, solar radiation, natural daylighting, indoor and outdoor airflow conditions, predicted mean vote (PMV), predicted percentage dissatisfied (PPD) Index, building cooling load, annual energy consumption, and energy use intensity (EUI). The analysis results were then compared with relevant specifications in Taiwan and other countries for evaluation and optimization. Among the nine items, solar radiation, building cooling load, annual energy consumption, and EUI were directly analyzed for their energy consumption. By contrast, sunlight, natural lighting, indoor and outdoor airflow conditions, PMV, and PPD were related to people’s comfort in an environment; however, they were also indirectly related to energy consumption. If the comfort analysis results reflected dissatisfaction or discomfort, then the building’s energy consumption required improvement.

The traditional Xindian Central Public Retail Market in northern Taiwan was chosen as the case study [ 29 ], in which a BIM model was constructed to conduct airflow condition, sunlight, and energy consumption analyses, after which the results of each item were assessed. For environmental simulation analysis, project data should first be prepared for each case, including parameters such as building geometry models, adjacent building volumes, impact factors for energy consumption, and climate. A suitable energy analysis software package should be evaluated and chosen for the energy analysis based on the conditions required by this study.

Based on the functions and features of each software package as well as the integrity of information conversion between the BIM model and energy analysis software, IES VE 2018 (Integrated Environmental Solutions Ltd., Glasgow, UK) was employed by this study as the green energy analysis software. IES VE 2018 can read gbXML files converted by Autodesk Revit, and its energy consumption analysis is more specific. The integrated software module is extremely flexible and adaptable, and the parameters can be adjusted according to the current situation, such as the number of people, equipment, exterior wall and window materials, and air-conditioning equipment. It could be used to simulate PMV and PPD, thereby enabling the identification of the reasons behind comfort issues and the comparison through simulated data with comfort requirement standards [ 37 38 ]. Accordingly, simulations using IES VE closely resemble actual situations, and the configurations that consider different situations can be directly fed back into the energy consumption data. Therefore, this study selected IES VE as its main energy analysis model.

The development of BIM, from its original two-dimensional (2D) plane operation to the current three-dimensional (3D) information modeling, has led to the integration of multidisciplinary talents, enabling them to participate in the entire life cycle of a building through BIM-related software and technology [ 36 ]. However, at present, the analysis and simulation functions of green building applications in BIM-related software are relatively simple and imperfect, requiring assistance from other professional energy analysis software packages to complete all necessary processes. Many such packages can now be linked with BIM models, such as Vasari, Ecotect, Green Building Studio, and IES VE. Table 2 provides an overview of the functions of each software package in its application to green building analysis.

After the energy model was constructed according to the abovementioned criteria, the gbXML file was exported and opened with IES VE for subsequent energy simulation analysis.

In addition to modeling the main building, adjacent buildings are a crucial factor in building energy consumption. They affect sunlight, solar radiation amount, and outdoor airflow conditions. Thus, the construction of surrounding building volumes is also critical. The construction of adjacent buildings in IES VE also follows a set of criteria listed as follows:

This study involved a green BIM process in the subsequent reconstruction phase, and the completed BIM model was drawn using Autodesk Revit 2018. Before modeling, the requirements of the BIM model that could be subjected to energy analysis in IES VE had to first be understood to serve as criteria for modeling. Therefore, the general model roll-out criteria were as follows:

Certainly, introducing the BIM model at different stages results in different workflows and required designs. Thus, a BIM model constructed when implementing various engineering applications should be individually designed according to the needs of the project.

The floor areas of each space in Xindian Central Public Retail Market were calculated through the Revit sheet list. Combining the obtained floor areas with the energy consumption density of the internal heat source in the space template ( Table 3 ) revealed the indoor load of each space ( Table 4 ).

In this study, most of the market equipment analyzed was old and unverifiable. Although the lighting, equipment, and air-conditioning system were inconsistent with the actual situation, the cited data were still based on credible sources; thus, the analysis results were consistent with common situations.

The energy configuration criteria were based on the standards of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, and the IES VE default values were used as the criteria for those not covered by the aforementioned standards. The sources of energy value assumptions were as follows:

The internal settings concern various parameter configurations, such as structural materials, types of use, windowing conditions, open-window conditions, and air-conditioning systems, which may all affect the energy performance of the model.

The meteorological information cited in this study was the “Hourly Typical Meteorological Years 3 (TMY3) for Taiwan Green Building Energy Simulation Analysis,” which covered eight locations in northern, central, southern, and eastern Taiwan, namely Taipei, Hsinchu, Taichung, Chiayi, Tainan, Kaohsiung, Hualien, and Taitung. TMY3 comprises months from various years that form 1-year hourly meteorological data. Each weather station acquires a long-term average status while simultaneously excluding abnormal climate conditions from 1990 to 2012 (23 years in total); this serves as the screening period for TMY. The selected months are determined based on a screening procedure known as the Sandia method, which was developed by the National Renewable Energy Laboratory in the United States. The research process includes analyzing the sensitivity of various meteorological elements (i.e., sunlight volume, temperature, wind velocity, wind direction, and humidity) for the building energy simulation [ 39 ].

Simulation analysis of green building energy consumption requires information such as building geometry volume, meteorological data, air-conditioning systems, and indoor load (i.e., people, equipment, and lighting) as well as a clear understanding of the parameters required for the analyzed items; some require actual surveying. Complete collection of the parameters can accelerate the analysis process and enhance the accuracy of the results.

2.5. Optimization Analysis

In this study, the following indicators were adopted as criteria for optimizing the analysis results. However, because of limitations of the existing conditions in the traditional market, not all analyzed items could be improved. Without changing the original usage of the market, this study proposed optimization suggestions for envelope heat radiation, energy consumption of the air-conditioning system, and indoor airflow. The remaining analyzed items were subjected to energy consumption evaluations to serve as reference for subsequent research and reconstruction.

2.5.1. Sunlight Analysis

• Purpose of the analysis

Sunlight directly affects the external radiation and indoor natural daylighting of the building, and the analysis results revealed the position that had the most sunlight, as well as shadow relationships with the adjacent buildings.

2.

Evaluation indicators and optimization plans

Improvements in people’s quality of life have led to an increasing emphasis on the right to enjoy sunshine [ 40 ]. The indicator used in this study was to examine sunlight during winter solstice and the effective hours of daylighting in adjacent houses (more than 1 h). According to the Taiwan’s Building Technical Regulations [ 41 ], for newly built buildings or additional constructions that exceed a height of 21 m, more than 1 h of effective sunlight during winter solstice should be ensured for the neighboring housing sites to guarantee their right to enjoy sunshine. Therefore, this indicator was adopted to discuss the relationship between the traditional market and adjacent buildings. However, because the case study involved analyzing an existing building with somewhat limited relationships with surrounding buildings, little improvement could be made in terms of sunlight. Therefore, this study only provides analysis results for the reference of subsequent reconstruction designs.

2.5.2. Envelope Heat Radiation Analysis

• Purpose of the analysis

If the wall and window materials are prone to heat absorption and have difficulty in heat insulation, indoor heat storage will result in increased temperatures. The analysis results revealed the amount of envelope heat radiation, based on which an improvement approach was proposed to reduce the effect of indoor heat storage, namely wall insulation. Wall insulation can reduce energy consumption and has a positive effect on building energy consumption.

2.

Evaluation indicators and optimization plans

Heat insulation is crucial in the design of green buildings because it enables rooms to retain their original internal heat while simultaneously avoiding excessive envelope heat as well as decreasing the design capacity of the building’s heating, ventilation, and air conditioning (HVAC) system [ 42 ].