Research on the Effective Sheltering Rates of Public Buildings in Villages in Western Sichuan, China—A Case Study of Ganbao Tibetan Village

Abstract

The western region of Sichuan Province, located in the Hengduan Mountains, is one of China’s most seismically active zones. Due to limited land resources, many villages in western Sichuan Province are situated in mountainous and valley areas, facing harsh climatic conditions, lagging economic development, and insufficient infrastructure. After experiencing seismic disasters, these villages often encounter challenges, such as cut-off mountain roads, difficulties in delivering relief supplies, and sharply a significant drop in nighttime temperatures due to the high-altitude climate. Consequently, in the case of the economic underdevelopment and limited resources, how to repurpose existing buildings for disaster relief has become a crucial issue for disaster prevention and mitigation in these villages. This paper takes Ganbao Tibetan Village, located in the alpine gorge regions of western Sichuan Province, as a case study. It evaluates the interior space utilization status of different types of existing public buildings during disasters, calculates the effective utilization rate of interior space disaster reduction conversion based on the spatial layout model, and extracts the typical interior space dimensions that are conducive to disaster relief and conversion of public buildings based on the interior space utilization characteristics of disaster relief. This study provides a reference for the design of public service buildings considering the requirements of disaster resilience transformation.

1. Introduction

In China, 81.8% of earthquakes primarily occur in the western regions [1]. Sichuan Province, located in the Hengduan Mountains, is a particularly earthquake-prone area. Additionally, due to limited land availability in western Sichuan, villages, including many ethnic minority settlements, are predominantly located in the alpine gorge regions. The irregular terrain and mountainous structures suffer more severe damage during earthquakes compared to plains, exacerbating earthquake disasters [2,3]. Irregular terrain significantly influences the distribution of earthquake damage [4,5] and has a notable impact on seismic activity [6], as evidenced by the numerous recorded seismic events and observed earthquake damage [7,8]. Therefore, rural areas in this region face greater earthquake threats and higher casualty rates than urban areas [9,10]. For example, the Wenchuan earthquake on 12 May 2008, caused massive casualties and economic losses in Sichuan Province. The “5.12” earthquake resulted in 70,000 deaths, 18,000 missing persons, 370,000 injuries, and up to 45 million people being left homeless [11]. The earthquake severely damaged 5.9325 million houses and caused the collapse of 5.4619 million houses [12], leading to a total economic loss of nearly 1 trillion RMB [13]. The Chinese government invested several years and nearly 1 trillion RMB to complete the post-disaster reconstruction work. Therefore, disaster prevention and mitigation efforts in ethnic villages located in earthquake-prone valley terrains must be given serious attention.

Currently, research on disaster shelters and the integration of normal and emergency usage in the fields of urban planning and architecture primarily focuses on urban areas. In the realm of architectural planning, significant achievements have been made in the study of disaster shelters, but the research subjects mainly concentrate on site selection distribution planning, capacity, and evaluation [14,15,16,17,18,19,20]. For instance, researchers such as K. Amini Hosseini [14] and Xu [17] have studied the land distribution and site selection of shelters using methods like a new index-based model and multi-criteria location model. Nagarajan [18] and Esposito [19] have conducted research on the capacity, allocation, and path optimization of shelters. Kusumo [20] and others have analyzed the spatial distribution differences between resident-selected shelters and official shelters.

Regarding research related to the seismic resistance of buildings, the focus is primarily on the seismic assessment and performance of structures. For example, Ruggieri et al. [21] presented a study on the seismic fragility of a sample of 15 reinforced-concrete school buildings built between the 1960s and 1980s in the province of Foggia. Additionally, Ruggieri et al. [22] used a methodology that allows assessing the seismic risk of reinforced concrete (RC) school buildings through the compilation of a factsheet. Figueroa et al. [23] conducted research on the seismic assessment of schools in El Salvador. You et al. [24] studied spatial correlation in building seismic performance for regional resilience assessment. Wang et al. [25] utilized lead rubber bearings (LRBs), which have been widely used in seismically isolated buildings to mitigate earthquake damages in highly earthquake-prone regions. Nicoletti et al. [26] provide insights into the usefulness of vibration data for damage detection in infilled frame structures.

In the research on village and town shelter sites, Chu et al. [27] conducted a quantitative study to determine the functional facility requirements of village-level shelters. Ma et al. [28], focusing on village earthquake evacuation capacity, discussed the main influencing factors and established an evaluation index system using an AHP adopting index scale and multi-level grey evaluation. Other researchers have focused on the issues and coping strategies of rural shelters. Karaye et al. [29] found that rural areas generally lack adequate shelters, so they proposed that disaster planning should consider increasing the area and number of shelters in certain locations. Bhattacharyya et al. [30] discovered that in the face of natural disasters such as cyclones, residents of coastal rural areas in India often find it difficult to convey accurate disaster information directly to the government, leading to poor rescue efforts. Therefore, they suggested establishing a knowledge information center within shelters to ensure digital resilience. Additionally, some scholars have focused on shelter configuration strategies. For example, Xie et al. [31] proposed area standards and configuration strategies for shelter buildings in rural communities in southwest China. The above study demonstrates the importance of utilizing public buildings or public service facilities in villages as shelters and addressing existing issues with these shelters. These measures are crucial for reducing disaster losses when disasters occur.

In summary, although academia has conducted extensive research on the conversion of public buildings into shelters, studies focusing on villages in underdeveloped, infrastructure-deficient, mountainous gorge regions are relatively scarce. The existing Chinese standards [32] also do not adequately meet the needs of rural areas; in particular, in-depth exploration at the architectural space level remains limited. In alpine gorge regions, there has been little discussion on how to effectively convert public building spaces into shelters during disasters and what forms can more efficiently provide shelter space for evacuees. Additionally, the shelter capacity in alpine gorge regions is relatively small, and the shelter area becomes even smaller after the conversion, resulting in insufficient capacity. Therefore, this study aims to take Ganbao Tibetan Village, a typical village in the mountainous gorge region of western Sichuan, as a case study to investigate the shelter efficiency of ethnic village shelters. This research aims to supplement the existing indicators of the efficiency of converting village public buildings for disaster use and provide data references for architectural design that considers both peacetime and disaster functions.

2. Research Subjects and Methods

2.1. Research Subjects

Ganbao Tibetan Village, characterized by its complex geographical environment, harsh climate, economic underdevelopment, and relatively concentrated population, serves as the focal point of this study. Specifically, this study selected Ganbao Tibetan Village as the research subject based on the following three factors: (1) Topographical Factors: Ganbao Tibetan Village is situated in an important location within the river valleys of western Sichuan. Its terrain is mostly hilly, and the village is densely constructed. Due to its unique topographical features, disasters can sever lifelines, disrupting the supply of water, electricity, food, and medicine. Therefore, temporary or short-term shelters are necessary during disasters. (2) Economic Factors: According to China’s 2023 economic development data, the gross domestic product (GDP) of Aba Prefecture is 50.319 billion Chinese Yuan (CNY), ranking last in Sichuan Province [33]. Due to the underdeveloped local economy, many residential buildings are self-built by villagers, often without standardized construction teams, resulting in poor residential safety. The public buildings constructed after the 2008 earthquake were funded by the state and built by local governments, resulting in higher construction quality compared to private buildings, making them more suitable for disaster prevention and evacuation. Although these buildings were designed according to China’s seismic requirements, ensuring safety, their efficiency in accommodating evacuees was not fully considered. (3) Cultural Factors: Ganbao Tibetan Village is the most well-developed village in terms of tourism facilities, with a relatively large population. Field surveys indicate that the permanent population of the village is over 1700 people. Considering the village’s age, scale, and development status, Ganbao Tibetan Village is particularly unique among the Garong Tibetans in the river valley region [34].

Ganbao Tibetan Village is one of the three characteristic ethnic villages in Lixian County, Aba Prefecture, Sichuan Province, China, alongside Taoping Qiang Village and Bajiao Carving Village. Its location is illustrated in Figure 1. Ganbao Tibetan Village (Figure 2) stands as one of the largest and most concentrated Jiarong Tibetan villages in Aba Prefecture. Situated approximately 8 km from Lixian County, Sichuan Province, it lies adjacent to National Highway 317, on the northwest bank of the Zagunao River [34]. Geographically, Ganbao Tibetan Village is positioned within a river valley flanked by mountains, exhibiting a layout characterized by “the river running through the village” [34], as depicted in Figure 3.

Due to the unique geographical location and climatic conditions of Ganbao Tibetan Village, the demand for indoor shelter space increases significantly during disasters and large diurnal temperature variations. Therefore, converting the function of public buildings to shelter buildings during disasters becomes crucial for accommodating evacuees. Additionally, when village residents face the need for shelter, it is essential to determine how many evacuees public buildings can accommodate and the efficiency of this accommodation. Thus, enhancing the effective sheltering efficiency of Ganbao Tibetan Village with minimal architectural modifications is a critical issue that needs immediate resolution.

2.2. Research Methods

This study primarily investigates the efficiency of transforming public buildings into disaster shelters using on-site surveys, measurements, drawings, and virtual layout illustrations of accommodation during disasters. Specifically, the approach involved using a laser rangefinder to measure the dimensions of three public buildings in Ganbao Tibetan Village and sketching them. Subsequently, these sketches were converted into electronic drawings using AutoCAD 2023, and AutoCAD 2023 area calculation techniques were used to obtain the area data of each public building.

The method for the determination of effective conversion rate of interior space in public buildings during disasters is based on relevant standard for disaster shelters in China [32] and scholarly research [31]. For emergency sheltering, it utilizes the per capita area specified in the norms, employing virtual layout designs based on the space occupied by individuals in standing and sitting positions during sheltering. For short-term sheltering, it uses the area occupied by disaster relief folding beds and aisle dimensions when individuals are lying down, also employing virtual layout designs. By using these virtual layout designs, the effective sheltering rate of public buildings can be calculated.

The effective sheltering rate in public buildings is defined as the ratio of the effective sheltering area to the total usable interior space. Here, the effective sheltering area is the sum of the ground projection area occupied by individuals during sheltering and the evacuation aisle area (during emergency sheltering, the aisle area is calculated as 0 square meters due to the fluid movement of people); the total usable interior space refers to the net area directly used for work or living purposes in the building’s floor plan.

Due to the possibility of rescue roads being cut off after disasters, this study considers the impact of different sheltering periods in virtual layout designs, including analyses of emergency sheltering and short-term sheltering scenarios. In both sheltering situations, the virtual layout design employs minimum per capita usage area.

2.3. Basis for Indicator Values

2.3.1. Basis for Indicator Values of Post-Disaster Conversion of Public Buildings

According to the provisions of the Chinese “Code for Design of Disasters Mitigation Emergency Congregate Shelter GB51143-2015”, public buildings should be designed to consider both regular use and post-disaster use whenever possible [32]. Given that Ganbao Tibetan Village is situated at an altitude of 3500 m, its climate exhibits typical high-altitude characteristics, with significant temperature differences between day and night, necessitating indoor shelter spaces for protection. Based on building standards, survey data, and census data for Ganbao Tibetan Village, the following indicators can be adopted, as shown in

Table 1. Domestic codes for sheltering buildings and their main area indicators.

Standardize	Maximum Opening Hours for Sheltering Design	Minimum Area per Capita	Area of Sheltering Buildings
GB51143-2015 Code for Design of Disasters Mitigation Emergency Congregate Shelter [32]	Emergency sheltering 1 day; temporary sheltering 3 days; medium-term sheltering 15 days; long-term sheltering 100 days	Effective sheltering area per capita for different sheltering periods: emergency, 0.5 m2; temporary, 1.0 m2; short-term, 2.0 m2; medium-term, 3.0 m2; long-term, 4.5 m2.	The total area of the public activity room should not be less than 200 m2; the area of the emergency medical and health center should not be less than 40 m2; the area of the room for emergency management and distribution of emergency materials should not be less than 40 m2.

.

2.3.2. Basis for Shelter Area Calculation

According to China’s “Code for Design of Disasters Mitigation Emergency Congregate Shelter GB51143-2015” [32], the design duration for emergency shelters is 1 day, with emergency sheltering primarily involving standing and squatting positions. The area per person for standing and squatting is set at 0.5 m², as shown in Figure 4. For short-term sheltering, which lasts from 3 to 15 days, lying down is required. Considering comfort, functionality, and economy, disaster relief folding beds are chosen as the lying down tool. Based on relevant scholars’ research and the referenced technical regulations [31,35], the dimensions for disaster relief folding beds are 1850 mm × 700 mm. The width of evacuation pathways should be no less than 0.60 m for every 100 people and should not be less than 1.00 m in total. The net width of single-sided pathways should not be less than 0.80 m, as shown in

Table 2. Dimensions of folding beds for shelter use.

Category	Foldable Bed Length (mm)	Foldable Bed Width (mm)	Single-Side Corridor Width (m)	Evacuation Passage Width (m)
Dimensions	1850	700	≥0.80	≥1.00

.

3. Selection of Sheltering Buildings and Calculation Results of Effective Sheltering Rate

3.1. Field Survey Results of Public Service Buildings in Ganbao Tibetan Village

Using a survey of the types of public service buildings in Ganbao Tibetan Village, it was found that the existing public service buildings include the village committee, health center, visitor center, and primary school (kindergarten). The village committee building is connected internally with the Boba Sengen Cultural Heritage Center; the visitor center and museum share the same building; and the health center primarily provides medical services to villagers, with a relatively small space. Since the primary school is abandoned, it is not included in subsequent discussions. The floor plans and current status of each public building are shown in Figure 5 and

Table 3. Basic information on the Village Committee in Ganbao Tibetan Village.

Content	Measured Area (m2)	Number of Floors	Area of Each Floor (m2)			Structural Type
Basic Information	523.70	3	First Floor Area: 243.18	Second Floor Area: 168.30	Third Floor Area: 112.22	Brick-Concrete Structure
Current Situation	Composition of Functional Spaces in the Building		Dimensions of Composing Spaces (m)			Plan Type
	Hall, Offices, Dressing Room		Interior Space Size Range		Corridor Width	“L-shaped”
			Length: 4.20–10.30 Width: 3.45–6.20		Width 1: 3.10 Width 2: 1.50
Floor Plan
First Floor Plan			Second Floor Plan		Third Floor Plan

Image Source: Drawn by the author.

,

Table 4. Basic information on the Health Center in Ganbao Tibetan Village.

Content	Measured Area (m2)	Number of Floors	Area of Each Floor (m2)		Structural Type
Basic Information	134.90	2	First Floor Area: 75.10	Second Floor Area: 59.80	Brick-Concrete Structure
Current Situation	Composition of Functional Spaces in the Building		Dimensions of Composing Spaces (m)		Plan Type
	Hall, Office, Consulting Room		Interior Space Size Range	Corridor Width	“I-shaped”
			Length: 4.60–8.00 Width: 3.10–5.80	Length: 11.00 Width: 1.20
Floor Plan
First Floor Plan				Second Floor Plan

Image Source: Drawn by the author.

and

Table 5. Basic information on the Visitor Center (Museum) in Ganbao Tibetan Village.

Content	Measured Area (m2)	Number of Floors	Area of Each Floor (m2)		Structural Type
Basic Information	187.90	2	First Floor Area: 137.50	Second Floor Area: 50.40	Brick-Concrete Structure
Current Situation	Composition of Functional Spaces in the Building		Interior Space Size Range (m)		Plan Type
	Hall, Exhibition Hall		Length: 6.80–9.20 Width: 2.70–8.60		“L-shaped”
Floor Plan
First Floor Plan			Second Floor Plan

Image Source: Drawn by the author.

.

3.2. Selection of Shelter Buildings in Ganbao Tibetan Village

Based on the survey results from on-site investigations, the relationship between public service buildings and population distribution was statistically analyzed, revealing that the population predominantly gathers near the activity plaza. Given the population distribution and in accordance with relevant Chinese national standards [32], the service area was delineated with the plaza at its center. This was done to ensure that public service buildings cover the majority of the population. Based on this delineation, it was found that the current public service buildings in Ganbao Tibetan Village, including the village committee, health center, and visitor center (museum), are all located within a 250-m radius from the village center and can serve as shelters during disasters. Specific details are illustrated in Figure 6.

3.3. Calculation Results of Effective Sheltering Rates for Ganbao Tibetan Village’s Sheltering Buildings

Based on field surveys and actual measurements, virtual layout designs were conducted for different public service buildings, resulting in the calculation of effective sheltering rates (the ratio of effective sheltering area to building usage area). The current public service buildings in Ganbao Tibetan Village, including the village committee, health clinic, and tourist center (museum), are all considered suitable for use as sheltering buildings during disasters. Following the relevant study [31] and current standards [32], virtual layout designs were implemented, with standing and crouching positions were adopted for emergency sheltering, utilizing a continuous arrangement based on a grid with a human body projection area of 0.5 square meters. For short-term sheltering, a lying position was utilized with disaster relief folding beds arranged accordingly. In both sheltering periods, aisle space needed to be reserved as evacuation routes, and areas around door openings were not designed for sheltering use due to potential evacuation obstacles. Different effective sheltering rates were obtained using these designs for various building types.

Based on the statistics of effective sheltering rates in public buildings in Ganbao Tibetan Village, two main types of spaces were identified: small spaces and large spaces. The effective sheltering rates of public buildings in Ganbao Tibetan Village are shown in

Table 6. Comprehensive table of effective sheltering rates for the Village Committee Building in Ganbao Tibetan Village.

Building Floors	Effective Sheltering Rate (Small Spaces)
	Emergency Sheltering Effectiveness Rate: 64.90%	Short-Term Sheltering Effectiveness Rate: 62.17%
First Floor Plan Layout
Second Floor Plan Layout
Third Floor Plan Layout

Source: Drawn by the author.

,

Table 7. Comprehensive table of effective sheltering rates for the Health Center in Ganbao Tibetan Village.

Building Floors	Effective Sheltering Rate (Small Spaces)
	Emergency Sheltering Effectiveness Rate: 51.20%	Short-Term Sheltering Effectiveness Rate: 56.78%
First Floor Plan Layout
Second Floor Plan Layout

Source: Drawn by the author.

and

Table 8. Comprehensive table of effective sheltering rates for the Ganbao Tibetan Village Visitor Center (Museum).

Building Floors	Effective Sheltering Rate (Large Spaces)
	Emergency Sheltering Effectiveness Rate: 61.91%	Short-Term Sheltering Effectiveness Rate: 54.60%
First Floor Plan Layout
Second Floor Plan Layout

Source: Drawn by the author.

. During emergency sheltering, the effective sheltering rates for small spaces range from 64.90% to 51.20%, while it is 61.91% for large spaces. It can be observed that there is no clear pattern in the effective sheltering rates between small and large spaces. During emergency sheltering, due to smaller per capita area occupancy and greater design flexibility, small and large spaces are less affected by traffic space and structural constraints. However, in emergency situations, certain specific spaces exhibit relatively lower effective sheltering rates, such as the small space in the health center, which is significantly influenced by functional layout and evacuation routes. In short-term sheltering situations, the effective sheltering rates for small spaces are 62.17% to 56.78%, while it is 54.60% for large spaces. Therefore, it can be concluded that small spaces have higher effective sheltering rates compared to large spaces. The primary reason is that in small spaces during short-term sheltering, the placement of shelter beds is less influenced by traffic space and structure. However, in large spaces during short-term sheltering, the arrangement of shelter beds is significantly affected by traffic space, structure, and evacuation doors. For example, the dimensions of column grids may restrict the placement of shelter beds, and the direction of door openings can affect aisle configurations.

Based on the effective utilization rate of disaster-to-peace conversion in public buildings, the study assessed the capacity to accommodate sheltered individuals during different sheltering periods. In emergency sheltering situations, existing shelter buildings can accommodate 1064 people, representing only 62% of the fixed population; during short-term sheltering, these buildings can only accommodate 268 people, representing 15% of the fixed population. Therefore, existing public buildings provide indoor shelter space for only a small portion of the population. Given the local climatic and topographical conditions, disasters occurring in winter or when rescue roads are cut off can lead to significant hazards. Hence, improving the effective sheltering rate of existing public buildings is necessary.

4. Strategies for Improving the Efficiency of Post-Disaster Conversion of Public Service Buildings

4.1. Strategies to Enhance the Effective Sheltering Rate in Typical Small Spaces of Ganbao Tibetan Village

After conducting on-site research, it was found that the typical small spaces in the village committee of Ganbao Tibetan Village are similar to those in the health center. Considering that individuals adopt a squatting posture during emergency sheltering, it is unlikely that modifying the sheltering space will significantly affect its effective utilization efficiency. However, for temporary or short-term sheltering situations, where disaster relief folding beds are needed and evacuation routes must be considered, modifications to the sheltering space will have a significant impact on its effective sheltering rate. Therefore, this study selected the typical office small space in the village committee as the research object. By adjusting the dimensions of this office for temporary and short-term sheltering, the study calculated the changes in effective sheltering rates under different layout configurations and aspect ratios and investigated the influence of evacuation doors on the effective sheltering rate.

As shown in

Table 9. Comprehensive analysis of effective utilization of small spaces in multiple comparisons.

Village Name	Original Length and Width Dimensions (Length: 5.70 m, Width: 4.50 m)	Adjustment Method Two (Length: 5.80 m, Width: 4.90 m)
Ganbao Tibetan Village (Village Committee)
Effective Shelter Area Zone
Effective Sheltering Rates	Highest Effective Sheltering Rate: 69.90%	Effective Sheltering Rate (Outward Opening Doors): 100%

Source: Drawn by the author.

, the original width of the typical office small space in the village committee of Ganbao Tibetan Village is 4.50 m, and the length is 5.70 m. Through virtual layout design, the maximum effective sheltering rate for temporary and short-term sheltering in the typical office small space of the village committee is 69.90%. To enhance the effective sheltering rate of the small space, the width dimension was increased by 0.50 m to 4.90 m, and the length was increased by 0.40 m to 6.10 m based on its original dimensions. Additionally, evacuation doors were set to open outward. With these adjustments, the effective sheltering rate of this small space can reach 100%. Moreover, outward-opening evacuation doors facilitate faster and safer evacuation of people, reducing the risk of crowd congestion and blockage.

By adjusting the length and width dimensions of the typical office small space, the effective sheltering rate has been significantly improved. The dimensions and positioning of evacuation doors have a significant impact on the effective sheltering rate of small spaces. When the evacuation door of the small space is placed at the evacuation corridor position and opens outward, the effective sheltering rate of the typical office small space reaches 100%. Overall, although some small spaces have high effective sheltering rates, they may not be considered their use for shelter during disasters, leading to some degree of resource wastage. However, through certain modifications, their effective sheltering rates can be increased effectively.

By enhancing the effective sheltering rates of small spaces in Ganbao Tibetan Village and formulating optimization strategies, similar approaches have been identified for neighboring villages such as Taoping Qiang Village and Bajiao Diao Village in western Sichuan. Four optimization models for typical small spaces in short-term sheltering scenarios have been summarized, as presented in

Table 10. Table of spatial optimization models for effective sheltering rates in typical small spaces of characteristic villages in Western Sichuan.

Category	Original Length and Width Dimensions (Length: 4.60 m Width: 3.21 m)	Adjusting Dimensions and Door Opening Direction (Length: 4.40 m Width: 3.15 m)
Pattern 1
Sheltering Efficiency	Maximum Sheltering Efficiency: 71.80%	(Outward Opening Door) Sheltering Efficiency: 100%
Category	Original Length and Width Dimensions (Length: 5.70 m Width: 4.50 m)	Adjusting Dimensions and Door Opening Direction (Length: 5.80 m Width: 3.75 m)
Pattern 2
Sheltering Efficiency	Maximum Sheltering Efficiency: 69.90%	(Outward Opening Door) Sheltering Efficiency: 99.84%
Category	Original Length and Width Dimensions (Length: 5.70 m Width: 4.50 m)	Adjusting Dimensions and Door Opening Direction (Length: 5.80 m Width: 4.90 m)
Pattern 3
Sheltering Efficiency	Maximum Sheltering Efficiency: 69.90%	(Outward Opening Door) Sheltering Efficiency: 100%

Source: Drawn by the author.

. For instance, concerning a typical small space in Taoping Qiang Village, originally measuring 4.60 m in length and 3.21 m in width, adjusting the dimensions to 4.40 m in length and 3.15 m in width allows for the horizontal arrangement of shelter beds, resulting in a 28.2% increase in effective sheltering rate, as depicted in Model 1. Similarly, for a medium-sized small space in Ganbao Tibetan Village, initially measuring 5.70 m in length and 4.50 m in width, adjusting the dimensions to 5.80 m in length and 3.75 m in width enables the horizontal and vertical arrangement of shelter beds, leading to a 29.94% increase in effective sheltering rate, as illustrated in Model 2. Furthermore, adjusting the dimensions to 5.80 m in length and 4.90 m in width allows for the placement of two horizontal rows of shelter beds, resulting in a 30.10% increase in effective sheltering rate, as shown in Model 3. For larger spaces, merging traffic spaces and controlling the length of the space based on the length of the shelter bed modules can enhance the effective sheltering rate.

4.2. Strategies to Enhance Effective Sheltering Rates in Typical Large Spaces in Ganbao Tibetan Village

Based on on-site investigations and measurements, the tourist center in Ganbao Tibetan Village mainly consists of large spaces. Therefore, this study will focus on discussing the effective sheltering rate of the tourist center as a typical large space. The first floor of the tourist center was selected as the research subject, and short-term virtual layout designs were generated to calculate the impact of different layout methods, aspect ratios, and the positioning of traffic evacuation doors and spaces on its effective sheltering rate.

As shown in

Table 11. Comprehensive analysis of effective utilization of centralized large spaces.

Village Name	Original Length and Width Dimensions (Length: 6.80 m Width: 6.00 m; Length: 9.20 m Width: 8.60 m)	Adjustment of Traffic Space and Dimensions (Length: 6.80 m Width: 6.20 m; Length: 9.20 m Width: 8.60 m)
Ganbao Tibetan Village (Visitor Center)
Effective Sheltering Area Zone
Effective Sheltering Rate	Highest Effective Sheltering Rate: 62.60%	Effective Sheltering Rate (Wall Movement): 72.30%

Source: Drawn by the author.

, the virtual layout design of the typical large space in the tourist center of Ganbao Tibetan Village follows the same approach as that for typical small spaces. Using a virtual layout design, the highest effective sheltering rate for short-term sheltering in the large space is 62.60%. By implementing local modifications and size adjustments to the original space, including repositioning walls and evacuation doors, and placing evacuation pathways and doors at the edges of walls, the original width dimension was adjusted from 6.00 m to 6.20 m. The optimized space achieved an increased effective sheltering rate of 72.30%. Through these optimization designs, the effective sheltering rate of the large space has been partially enhanced. In large spaces, due to functional design requirements, there are multiple entrances, corridors, and evacuation stairs, which segment the overall space and significantly affect sheltering layouts, thereby reducing the effective sheltering rate. Hence, the positioning of traffic spaces and evacuation doors is identified as one of the primary factors influencing the effective sheltering rate in large spaces.

Simultaneously, regarding the large spaces around Ganbao Tibetan Village and Taoping Qiang Village, virtual layout designs were conducted, and optimization strategies for large spaces were summarized. For short-term sheltering situations, there are two typical optimization models for effective sheltering rates in large spaces, as shown in

Table 12. Table of spatial optimization models for effective refuge rates in typical large spaces of characteristic villages in Western Sichuan.

Category	Original Length and Width Dimensions (Length: 6.80 m Width: 6.00 m; Length: 9.20 m Width 8.60 m)	Adjustment of Dimensions and Traffic Space (Length: 6.80 m Width: 6.20 m; Length: 9.20 m Width 8.60 m)
Pattern 1
Sheltering Efficiency	Maximum Sheltering Efficiency: 62.60%	(With Wall Movement) Effective Refuge Rate: 72.30%
Category	Original Length and Width Dimensions (Length: 13.40 m Width: 8.50 m; Length: 19.00 m Width: 15.68 m)	Adjustment of Dimensions and Traffic Space (Length: 13.40 m Width: 8.90 m; Length: 19.00 m Width: 15.68 m)
Pattern 2
Sheltering Efficiency	Maximum Sheltering Efficiency: 77.30%	Sheltering Efficiency: 79.00%

Source: Drawn by the author.

. For the typical large space in Ganbao Tibetan Village, adjusting the positioning of traffic spaces and doors, with a width dimension set at 6.20 m, resulted in the highest effective sheltering rate as depicted in Model 1. For Taoping Qiang Village’s typical large space, resizing to a width dimension of 8.90 m achieved the highest effective sheltering rate as shown in Model 2. Based on this, optimizing the size and traffic space design through these two models for large spaces can enhance the effective sheltering efficiency of shelter buildings. However, the conclusions indicate that significant improvements in the effective sheltering rate were not observed after adjustments were made to typical large spaces.

In summary, the effective sheltering efficiency of typical small spaces significantly improves after dimensional modifications, while that of typical large spaces does not show notable improvement. The effective sheltering efficiency of small spaces is clearly influenced by dimensions, whereas in large spaces, it is affected by various factors beyond just length and width. There are likely two main reasons for this. First, the internal functionality of large spaces is complex, with numerous traffic hubs that limit the placement of shelter beds, thus constraining modifications. Second, the large span of these spaces makes shelter beds more susceptible to interference from structural columns. Therefore, in the design process, the effective sheltering efficiency of large spaces can be enhanced by making safe and rational adjustments to the distance and layout of columns through structural calculations.

5. Conclusions

This paper addresses the inadequacy of existing Chinese regulations for certain village settings by studying the effective sheltering rate of public buildings in typical villages in western Sichuan, characterized by complex geographical environments, harsh climates, underdeveloped economies, and relatively concentrated populations. Furthermore, it explores the optimization of indoor spaces and identifies the following three key points.

First, based on the virtual layout design of public buildings in Ganbao Tibetan Village, the effective sheltering rate was calculated. In emergency sheltering situations, the effective sheltering rate for small spaces ranged from 51.20% to 64.90%, while it was 61.91% for large spaces. For short-term sheltering situations, the effective sheltering rate for small spaces ranged from 56.78% to 62.17%, while it was 54.60% for large spaces. The data indicate that both large and small spaces have an effective sheltering rate between 51% and 65%. Some areas within the buildings are unusable for sheltering, accommodating only a small portion of people indoors.

Second, through the study of the effective sheltering rate in Ganbao Tibetan Village, it was found that there is a discrepancy between the effective sheltering rates of large and small spaces, with the effective sheltering rate for large spaces not being significantly higher than that for small spaces. This is due to the influence of internal functional use, building internal structure, and the location and opening direction of evacuation doors on the effective sheltering rate of large spaces. Meanwhile, by adjusting the dimensions, evacuation door positions, and structural walls of small and large spaces in Ganbao Tibetan Village, the effective sheltering rate for small spaces was increased to nearly 100% (excluding structural space), and it was increased to 72.30% for large spaces.

Third, in the small-space model, through exploration of space optimization patterns, it was found that minor adjustments in dimensions from the perspective of disaster-to-peace conversion can significantly enhance the effective sheltering rate. Furthermore, optimal strategies for improving the effective sheltering rate were discussed across various dimensions. For short-term sheltering, based on survey data, small-space dimensions range from 2.50 m to 6.00 m in width and from 4.00 m to 7.00 m in length. In disaster-to-peace integrated architectural design and renovation, when the width ranges from 2.50 m to 3.40 m, the recommended optimal width is 3.15 m. This involves arranging disaster relief folding beds in a single horizontal row, maximizing both effective sheltering rate and capacity. For widths ranging from 3.40 m to 4.10 m, the optimal width is 3.75 m, utilizing a combination of one horizontal row and one vertical row of disaster relief folding beds to achieve peak effective sheltering rate and capacity. When widths range from 4.10 m to 6.00 m, the optimal width is 4.90 m, employing a layout of two horizontal rows of disaster relief folding beds to achieve maximum effective sheltering rate and capacity. In larger spaces, evacuation doors should be positioned at the edges of walls and opened towards the aisles. Regarding column grid layout, it is recommended to design column spans based on the modular dimension of disaster relief folding beds, with a short side dimension of 0.7 m, to maximize accommodation of sheltering individuals.

Overall, this study derived a “commonalities“ model for improving the effective refuge rate based on the “individualistic” optimization methods applied in Ganbao Village. The model can be utilized to enhance the effective refuge rate in similar spaces. However, the study primarily focused on investigating the effects of size adjustments and local modifications on the effective refuge rate of public refuge buildings, without fully considering the stability and reliability of the structures of residential and public buildings after the modifications. This includes calculations and assessments of the structural strength and seismic performance of the modified buildings. In future research, an emphasis will be placed on examining the rationality of building structures under suitable refuge building sizes in the context of disaster mitigation, ensuring that the modified refuge buildings can provide sufficient safety assurance during disasters.