Analysis of Evacuation Efficiency for Differently-Abled People in Multi-Layered Buildings Based on Assistance Ratio

Abstract

The term “differently-abled” refers to people with mobility difficulties, including the disabled and the elderly. In order to explore the optimal evacuation efficiency, in emergencies, of different floors in multi-layered buildings where differently-abled people reside, this study has established a mixed evacuation model based on the characteristics of the evacuation behavior of differently-abled people and non-differently-abled people. This model simulated the impact of evacuation strategies on different floors for differently-abled people at various assistance ratios. Through the comparative analysis of various evacuation strategies, an evacuation efficiency analysis model was constructed, which is suitable for multi-layered buildings where differently-abled people reside. The research indicates that, for stair-determined evacuation strategies, when the proportion of assisting personnel exceeds 70%, there is a noticeable improvement in overall evacuation efficiency. For elevator-determined evacuation strategies, evacuating middle floors with unrestricted methods can enhance evacuation efficiency. The analysis model for optimal evacuation efficiency on each floor that is presented in this study, using a five-story building as an example, can clearly and accurately determine evacuation strategies for multi-layered buildings where differently-abled people reside.

1. Introduction

With increases in population and the acceleration of the aging process, the number of disabled and elderly people has been gradually growing. Special housing for these individuals, such as nursing homes and care facilities, has also been on the rise. When emergencies occur, the inevitable mixed evacuation of differently-abled people and non-differently-abled people is a significant concern. Researching the efficiency of the mixed evacuation of differently-abled people and non-differently-abled people is crucial in reducing accident losses and preventing harm to individuals.

The term “differently-abled” refers to people with limited mobility, including the disabled and the elderly. These vulnerable groups are more susceptible to harm during emergencies. Differently-abled people often have mobility or safety information processing impairments, resulting in slower evacuation speeds and longer emergency response times, making their evacuation situations more complex. Additionally, the presence of care providers and other individuals alongside differently-abled people can significantly affect the evacuation of the general public.

Scholars worldwide have conducted extensive research on the characteristics of evacuations that involve differently-abled people. For instance, Proulx monitored the evacuation of elderly residents during an evacuation drill and recorded their movement speed [1]. Koo conducted a series of simulations on the evacuation of disabled individuals in typical scenarios, concluding that delaying the evacuation of wheelchair-bound individuals, or allowing non-differently-abled people to use stairs while the wheelchair-bound individuals use elevators, can effectively reduce evacuation time [1,2,3,4]. Studies by Min and Jiana have demonstrated that a combination of stair and elevator usage can significantly reduce evacuation time [5,6]. Pearson conducted a study on the evacuation capability of elderly people living with joint disorders who required wheelchair assistance [7]. Fujiyama conducted a speed study on the stair-descending situations of 12 female and six male individuals aged 60–81, by requiring them to descend stairs at their normal and fastest speeds [8]. Kwaw coupled evolutionary game models with pedestrian motion models to study the influence of collective assistance behavior on evacuation efficiency in emergency scenarios, concluding that a certain number of assistance actions can enhance evacuation efficiency [9].

In summary, in mixed evacuation scenarios involving both non-differently-abled and differently-abled people, assistance behavior can effectively improve evacuation efficiency; however, previous research primarily focused on the impact of differently-abled people on overall evacuation situations in environments largely occupied by the general public. There is a lack of research on evacuation scenarios in locations specifically designed for differently-abled people. This study establishes a model for differently-abled population residences, simulates the mixed evacuation of differently-abled and non-differently-abled populations, and considers the assistance provided by non-differently-abled populations to differently-abled populations as an important factor affecting evacuation efficiency. It analyzes optimal evacuation efficiency under different evacuation forms on each floor, and uses this analysis to determine the best mixed evacuation plan. This provides valuable insights for rescue personnel ratios and evacuation strategies in emergency evacuations for buildings that cater to differently-abled people, such as nursing homes and care facilities.

The structure of the rest of this study is as follows: Section 2 introduces the current status of relevant research on personnel safety evacuation. Section 3 introduces the evacuation objects studied, evacuation methods used, evacuation models created, and the relevant parameter settings. Section 4 simulates evacuation under different evacuation methods based on the established model. Based on the simulation results, it also conducts a macro-analysis of evacuation efficiency under various assistance ratios. Section 5 systematically analyzes the evacuation efficiency of different evacuation methods through the control variable method. Section 6 summarizes the research content of this paper.

2. Related Works

Current research on personnel safety evacuation mainly falls into two categories: one is to establish a safety evaluation model for existing safety evacuation patterns, conducting safety assessments based on relevant safety factors; the other is to apply certain technologies to plan evacuation methods for existing evacuation environments.

2.1. Emergency Evacuation Safety Assessment

Daniel investigated recent solutions for crisis management in smart cities, proposed a systematic definition for emergencies, and emphasized that, in the development of smart cities, the city should be viewed as a broader system with highly interconnected subsystems [10]. Zhang established an evaluation index system with 16 indicators including people, equipment, environment, and management factors, and constructed a comprehensive evaluation framework for the emergency evacuation capacity of urban subway stations based on the TOPSIS–GRA method [11]. Peng proposed a multi-disciplinary fusion algorithm based on a digital platform from the perspective of emergency evacuation, which included the reconstruction and analysis of population and urban elements, specialized evacuation simulations, and a quantitative assessment system for different layout schemes [12]. Li has proposed a dynamic risk assessment method combining dynamic target detection and risk assessment based on DNN (Deep Neural Network). This method utilizes a real-time detection approach based on the YOLO (You Only Look Once) algorithm to extract artificial hazard factors that have a significant impact on the evacuation process, thereby achieving real-time evaluation of the evacuation risk level [13].

2.2. Evacuation Route Planning

Oluwafemi analyzed the progress of current research on underground mine fire, constructed a priority-based network planning algorithm, and proposed a new method for an underground emergency evacuation management system, aiming to maximize the efficiency of evacuation exit utilization [14]. Using oblique photogrammetry technology, Xu generated an accurate 3D model scene of emergency shelters, providing an effective basis, in terms of space, for positioning emergency facilities to help emergency command and decision makers [15]. Sungwoo proposed a disaster evacuation route guidance system based on map API, which can identify flood situations in forest areas, recreational forests, and parks. This system calculates an evacuation route based on map API and sends it to the nearest shelter, to users, helping them safely evacuate [16]. Zhang, taking one subway station as an example, analyzed the fire development situation in different locations of the station, studied the safe evacuation of subway station personnel, and optimized the layout of the public area in the station based on the actual situation, thus improving evacuation efficiency [17].

From the aforementioned literature, it can be observed that current research on safe emergency evacuation mainly focuses on detailed analyses of the on-site environment, with less attention given to individual differences (such as varying mobility speeds) and detailed self-organizing phenomena during the evacuation process (such as assisting behaviors among personnel); however, these factors are crucial and cannot be ignored in safe evacuation, hence the need for further research.

3. Evacuation Scenario Setup

3.1. Software Introduction

Pathfinder 2021, a personnel evacuation simulation software, is a character-based simulator that achieves the simulation of each person’s escape path and the time it takes by defining key parameters (number of people, walking speed, and distance). Pathfinder enables pedestrians to continuously find new and better evacuation path curves while roughly following the current moving path, and can make adjustments to the constantly changing environment, helping pedestrians to, for example, avoid walls, plan passages, and avoid other pedestrians. It can simulate various types of buildings and disaster situations, and the calculation results are accurate. It is widely used in the design of evacuation paths and safety evacuation results assessment for various buildings [18,19].

3.2. Evacuees

Due to the fact that evacuation paths for differently-abled individuals with mobility impairments involve elevators, their evacuation time is not significantly affected by the assistance ratio; however, the focus of this study is on understanding variations in evacuation times for differently-abled people under various assistance ratios. Therefore, in the simulations, the evacuees considered only include the non-differently-abled public and differently-abled people without mobility impairments (including people with crutches, the blind, and others.). When non-differently-abled individuals provide assistance to differently-abled people through evacuation chairs, they form an assistance group. The ratio of assisting personnel to the number of differently-abled people is referred to as the “differently-abled people assistance ratio” or, simply, the “assistance ratio” [20].

3.3. Evacuation Methods

The evacuation design in this study is based on relevant regulations for residential buildings accommodating differently-abled individuals. In China, to ensure personnel safety, buildings for differently-abled populations should be equipped with fire-fighting elevators that can be used by differently-abled populations during emergency evacuation. Hence, the term “elevator” in the evacuation process specifically refers to accessible elevators that can be used in emergency situations.

Typically, multi-story buildings do not have specific emergency evacuation plans for staircases and elevators, leading to the inefficient utilization of evacuation routes during emergencies. Furthermore, directing individuals to different evacuation methods on each floor, during emergencies, is often inefficient. Therefore, it is necessary to research more scientifically sound emergency evacuation strategies to enhance evacuation efficiency. In the simulations, to ensure that people follow the designated evacuation plan, a method is employed of directing individuals towards designated evacuation routes by closing all other evacuation routes except for the specified ones during emergency situations.

3.4. Evacuation Scenarios

During the simulation of the evacuation of differently-abled groups, it was observed that, when the number of floors exceeded five, the safe evacuation time for differently-abled groups to evacuate to the first floor via stairs is more than 7 min. Considering safety, however, the latest Chinese building fire protection code, “Code for Fire Protection Design of Buildings” (GB50016-2014) [21], stipulates that the safe evacuation time for civil buildings with fire resistance grades of Level 1 and Level 2 cannot exceed 6 min.

Therefore, this study used Pathfinder software to create an evacuation model, taking a five-story building as an example to simulate the evacuation scenario for differently-abled people. The experimental simulation scenario is depicted in Figure 1. This experimental model consists of five floors, each with a height of 3.3 m. Because the subject of this study is the impact of evacuation methods on evacuation efficiency, and the personnel on the first floor do not need to evacuate via stairs or elevators, evacuation personnel are not set on the first floor. In the four-layer planar graph structure, there are a total of 240 people, including 30 differently-abled members and 30 non-differently-abled members on each floor. The positions of the 30 differently-abled members on each layer are random, and the 30 non-differently-abled members are placed near the differently-abled members.

Boyce and Kuligowski have contributed to the study of evacuation speeds for differently-abled people with mobility impairments [22,23]; however, physical differences exist between Caucasian and Asian individuals, leading to varying evacuation capabilities. Jiang examined the evacuation characteristics of differently-abled people in China, but their research only covered 29.07% of disabled individuals in the country at that time, and evacuation speeds for differently-abled people in their study significantly exceeded those of Boyce and Kuligowski and others [24].

As a result, there is a lack of specific reference data for the evacuation capabilities of differently-abled people in China. To ensure the validity of the research results, the evacuation speed of the non-differently-abled individuals in this study is taken as the average of the results of both Boyce and Kuligowski, and Jiang’s, studies, while the evacuation speed of the differently-abled people in this study is taken as the least favorable value, as per the study by Boyce and Kuligowski. According to Adams’s research on evacuation chair speeds and the evacuation width provided by Pathfinder software, the personnel parameters for this study are presented in

Table 1. Mixed individual evacuation parameters.

The Type of Ground	Evacuees	Egress Width: b (mm)	Maximum Speed: v (m/s)
level ground	non-differently-abled individuals	455	1.40
	differently-abled individuals	455	0.95
	assistance groups	900 × 455 (length × width)	0.95
staircase	non-differently-abled individuals	455	1.12
	differently-abled individuals	455	0.36
	assistance groups	900 × 455 (length × width)	0.75

[25].

Because pedestrians tend to reduce their width when navigating through congested areas, the model allows them to reduce their physical size to 80% of the original width when passing through crowded locations. Elevator parameters are set at a door width of 1.5 m, an operational acceleration of 1.2 m/s², a maximum speed of 2.5 m/s, and a waiting time of 7 s. Staircase parameters include a net width of 1.5 m for each flight of stairs. This simulation primarily investigates the impact of using elevators and staircases in multi-story buildings on evacuation efficiency; therefore, both the staircase and elevator lobbies on each floor are designated as safe exits.

4. Study of Optimal Evacuation Efficiency on Each Floor

Each floor has both staircase and elevator evacuation options, and using different evacuation methods results in varying evacuation scenarios. To accurately understand the specifics of the evacuation process, it is necessary to simulate each floor’s evacuation plans. By analyzing the connections and differences between these plans, we can determine optimal evacuation efficiency patterns for multi-story buildings.

4.1. Evacuation Efficiency under Different Evacuation Plans

To explore evacuation efficiency under different combinations of evacuation plans on each floor, this study conducted evacuation simulations for various scenarios. Since having individuals on the second floor take the elevator would reduce the number of elevator uses by individuals on other floors, decreasing the overall evacuation efficiency for the entire building, this study’s plan involved having all individuals on the second floor evacuate via the staircase. By using the enumeration method, we listed 27 other different scenarios; additionally, we set up a control group with no restrictions on evacuation methods. The evacuation times under different scenarios are shown in Figure 2. In the table, “L”, “D”, and “W” represent the use of stairs, elevators, and unrestricted methods for evacuation on each floor, respectively. For example, “2L3W4W5D” means that this scenario involves individuals evacuating using stairs on the second floor, unrestricted methods on the third and fourth floors, and the elevator on the fifth floor.

Based on the simulation results, curves depicting the variation of the shortest evacuation times, and evacuation times for scenarios closely matching the shortest time under various assistance ratios, are plotted, as shown in Figure 2. From the table, we can observe the following:

(1)

For a five-story building evacuation, when the assistance ratio is less than 40%, the time variation curve for scenario C6: “2L3W4D5L” closely matches the curve for the shortest evacuation time. This alignment is especially evident at 0% and 20% assistance ratios, where the curves completely overlap, and at 10% and 30% assistance ratios, where the evacuation times are within 3% of the shortest time. Therefore, for a five-story building evacuation with an assistance ratio below 40%, C6 is recommended as the optimal scenario.

(2)

For a five-story building evacuation, when the assistance ratio is equal to or greater than 40%, the time variation curve for scenario C21: “2L3L4W5L” closely matches the curve for the shortest evacuation time. This alignment is particularly notable at 40%, 60%, 70%, 90%, and 100% assistance ratios, where the evacuation time is the shortest. Even at 50% and 80% assistance ratios, evacuation times are within 3% of the shortest time. Therefore, when the assistance ratio is equal to or greater than 40%, C21 is recommended as the optimal scenario.

(3)

From the shortest evacuation times for various assistance ratios in Figure 3, it is evident that, when the assistance ratio is less than 70%, increasing the assistance ratio does not significantly reduce the minimum evacuation time; however, once the assistance ratio exceeds 70%, assistance has a notable impact on the evacuation of differently-abled people. Therefore, in multi-story buildings where differently-abled people reside and evacuation is required, the self-evacuation capabilities of differently-abled people can be effectively utilized when the assistance ratio is less than 70%. Therefore, due to the conditions of differently-abled people, assistance is needed. In order to enhance overall evacuation efficiency, the ratio of assisting personnel should be greater than 70%. When the assistance ratio is 100%, the evacuation efficiency is the highest. The reason for the lack of improvement in evacuation efficiency beyond 70%-assistance ratio in scenario C6 is explained in Section 4.2.

4.2. Efficiency of Different Evacuation Types

Based on the relationship between evacuation times for different scenarios and changes in the assistance ratio, evacuation types can be categorized into two groups: elevator-determined evacuation and staircase-determined evacuation.

Elevator-determined evacuation refers to scenarios where evacuation times do not decrease and, in some cases, even increase with an increase in the assistance ratio. In these scenarios, the individuals who use elevators are the last to exit in the simulation. Trends in evacuation times for elevator-determined evacuation with changing assistance ratios are shown in Figure 4.

Staircase-determined evacuation refers to scenarios in which evacuation times decrease as the assistance ratio increases. In these scenarios, individuals using the staircase are the last to exit in the simulation. Staircase-determined evacuation scenarios are illustrated in Figure 5.

(1)

Analysis of elevator-determined evacuation efficiency. Elevator-determined evacuation times are primarily determined by elevator evacuation times. In scenarios where elevators are available, evacuees are more inclined to use elevators for downward evacuation. This leads to a situation where the waiting queues at elevator entrances become excessively long, causing elevator evacuation times to be significantly longer than staircase evacuation times. Therefore, evacuation efficiency is relatively less affected by the assistance ratio in elevator-determined evacuation scenarios; however, when the assistance ratio is quite high, an increase in the number of assistance groups can lead to congestion at elevator entrances, resulting in longer evacuation times.

Furthermore, analysis of scenarios like C3, C12, C15, and others reveals that, within the same category of elevator-determined evacuation, if one or more floors employ unrestricted evacuation, the evacuation time is significantly shorter than in scenarios with exclusive elevator evacuation. A comparison of evacuation times for different elevator-determined evacuation scenarios is shown in Figure 6. When unrestricted evacuation is employed on intermediate floors, evacuees can make a reasonable choice of evacuation mode based on the specific congestion conditions of both elevators and staircases, thereby avoiding congestion-related decreases in evacuation efficiency.

(2)

Elevator-determined evacuation efficiency analysis. Elevator-determined evacuations occur due to limited elevator resources or unreasonable usage situations. Evacuation time, in this case, depends on the speed at which people descend the stairs. In staircase-determined evacuation, the overall evacuation speed for differently-abled people is influenced by the assistance ratio. Although the evacuation speed of non-differently-abled individuals decreases from 1.12 m/s to 0.75 m/s when assisting differently-abled people during staircase evacuations, the evacuation speed of differently-abled people doubles, increasing from 0.36 m/s to 0.75 m/s. Consequently, staircase-determined evacuation results in decreased evacuation times as the assistance ratio increases.

From the above, it is clear that staircase-determined evacuation is suitable when elevator resources are limited, and the assistance ratio for differently-abled people in these scenarios is relatively high. Elevator-determined evacuation is suitable for situations with a lower assistance ratio. It effectively reduces the time difference between evacuations with assistance and evacuations without assistance in low-assistance ratio scenarios. This effectively compensates for the slower evacuation speed of differently-abled people using stairs. Therefore, buildings accommodating a significant number of differently-abled people should be equipped with evacuation elevators that meet emergency requirements.

5. High-Rise Building Optimal Evacuation Efficiency

5.1. Optimal Evacuation Efficiency in High-Rise Buildings

During multi-story building evacuations, common practice is for the residents of the highest floors to use elevators while residents on lower floors use stairs for evacuation; however, this practice contradicts recommended scenarios C6: 2L3W4D5L and C21: 2L3L4W5L, where the fifth floor also uses stairs for evacuation. To study the efficiency of elevator use in high-rise buildings, considering the different efficiency trends of elevator-determined evacuation and staircase-determined evacuation with changing assistance ratios, the two evacuation modes are separated.

(1)

Staircase-determined evacuation for floors four and five. Evacuation modes for the fourth and fifth floors are determined. Based on scenario C27: 2L3L4L5L, the evacuation modes for the fourth and fifth floors are changed to elevators in scenarios C24: 2L3L4D5L and C26: 2L3L4L5D. Changes in time are visually represented by comparing scenarios C24 and C26. The result is reduced evacuation times, as shown in Figure 7.

From Figure 6, it can be observed that the time saved by using an elevator for either the fourth or fifth floor is approximately the same; therefore, the impact on efficiency is roughly similar when considering the use of an elevator for either the fourth or fifth floor. The recommended evacuation plan should take into account the evacuation efficiency for the fourth floor.

(2)

Determination of fourth- and fifth-floor evacuation methods in elevator-determined evacuation. The analysis method for elevator-determined evacuation is the same as that for staircase-determined evacuation. In order for third-floor evacuation to be an elevator-determined scheme (C18: 2L3D4L5L), we modified the evacuation methods of the fourth and fifth floors using elevators. This led to the creation of two schemes: C15: 2L3D4D5L and C17: 2L3D4L5D. By comparing changes in scheme duration, we determined the efficiency of using elevators on the fourth and fifth floors. The shortened times for each floor using elevators are shown in Figure 8. From Figure 8, we can see that the elevator-determined evacuation scheme C15 yields the most significant time reduction; therefore, when adopting an elevator-determined evacuation, the recommended evacuation method for the fourth and fifth floors is 4D5L.

5.2. Optimal Evacuation Efficiency for High Floors in the Building

When considering the efficiency of using elevators on the fourth and fifth floors in staircase-determined evacuation, we found that time savings are roughly equivalent. To further determine the optimal evacuation methods for the fourth and fifth floors, we modified the evacuation methods on the fourth floor while keeping the fifth floor as an unlimited method within the C27: 2L3L4L5L scheme. A comparison of the evacuation times for different methods on the fourth floor is presented in Figure 9. From Figure 9, we can observe that, when other floors are using stairs and the fourth floor uses an unlimited method, the evacuation efficiency is the highest. Similarly, by comparing C26 and C27, it can be deduced that, when other floors use stairs, the fifth floor using an elevator results in the shortest evacuation time, but it is still longer than the evacuation time compared to the scenario where other floors use stairs and the fourth floor uses an unlimited method. Therefore, to avoid any reduction in evacuation efficiency that can occur when the fourth and fifth floors simultaneously use elevators, in accordance with the stair-determined evacuation scheme, the recommended evacuation methods for the fourth and fifth floors are 4W5L.

(1)

Analysis of evacuation efficiency on the fifth floor. During the simulation process, it was found that there was more severe congestion among differently-abled people in stairwells compared to non-differently-abled individuals, especially on lower floors where congestion was more pronounced. When upper floors use stairs for evacuation, middle floors can make greater use of elevators. This approach has two benefits: it effectively alleviates the congestion that occurs in stairwells on middle floors during short periods; and it allows individuals on the highest floor to flexibly choose their evacuation method based on the situation in the middle floor stairwells. Therefore, it is recommended for upper-level buildings to use stairs for evacuation.

(2)

Analysis of evacuation efficiency on the fourth floor. Regarding evacuation methods for the fifth floor, when using stairs for the fourth floor, in the case of using an elevator-determined evacuation scheme, ample elevator resources make it effective for the fourth floor to entirely use elevators, which can compensate for the slower evacuation of differently-abled people. It also prevents congestion with fifth-floor occupants at the stairwells on the fourth floor. In the case of a stair-determined evacuation scheme, where elevator resources are limited, using the unrestricted evacuation method on the fourth floor has multiple advantages. First, it helps distribute the flow of people on the fourth floor, alleviating congestion at the elevator doors. It also fully leverages the evacuation capabilities of evacuees and allows high-floor occupants to choose their path based on the crowding status in the stairwells, easing congestion on the lower- and middle-floor stairwells.

5.3. Optimal Evacuation Efficiency on Intermediate Floors

Because the recommended evacuation method for the fourth and fifth floors with a stair-determined scheme is 4W5L, under the 2L4W5L evacuation scheme, the third floor’s recommended method was studied. A comparison of evacuation times for different third-floor evacuation methods is shown in Figure 10. According to Figure 10, using stairs for evacuation on the third floor provides the highest efficiency, and the optimal evacuation method is 2L3L4W5L, which is consistent with the best evacuation method for an assistance ratio of less than 40% in the simulation results.

Similarly, for elevator-determined evacuation on the fourth and fifth floors, the recommended strategy is 4D5L; therefore, under evacuation plan 2L4D5L, a comparison of evacuation times for different methods on the third floor is shown in Figure 11. From Figure 11, it can be observed that, on the third floor, the unlimited evacuation method results in the highest efficiency, and the optimal evacuation strategy is 2L3W4D5L, which aligns with the simulation result in which assistance ratio is greater than or equal to 40%, matching the conclusions drawn. This consistency supports the idea that stairwell-determined evacuation is suitable for low-assistance ratio evacuations, while elevator-determined evacuation is more effective for high-assistance ratio evacuations. Upon analysis, the reasons for this are as follows:

(1)

When the assistance ratio is low, evacuating all middle floors using elevators leads to excessive elevator time consumption, which is considered a waste of resources for those middle floors; however, relying solely on stairwells is less effective due to limited assistance for the middle floors, making it more challenging for differently-abled people to evacuate, resulting in longer evacuation times. Therefore, an unrestricted evacuation method is more efficient in this scenario. In this case, differently-abled people without assistance can use elevators for descent, while those with assistance, both differently-abled and non-differently-abled individuals, can effectively utilize stairwells for evacuation.

(2)

When the assistance ratio is high, most differently-abled people have assistance from non-differently-abled individuals. In the case of mid-level floors, the use of elevators is less effective compared to upper-level floors, and mid-level evacuees can efficiently and in an orderly fashion descend via the stairwells, reducing congestion.

To more concisely display the analysis process of the optimal evacuation plan for each floor, one stair-based evacuation is used as an example to create the flowchart, as shown in Figure 12.

6. Conclusions

This study, using a five-story building as an example, investigated evacuation strategies for differently-abled people in multi-story buildings under various assistance ratios. The research identified two types of evacuation strategies for differently-abled people: elevator-determined evacuation and stair-determined evacuation. Based on these, a comprehensive evacuation efficiency analysis model, specifically for multi-story buildings where with differently-abled reside, was proposed, leading to the following conclusions:

For stair-determined evacuation, when the assistance ratio is below 70%, improvement in evacuation efficiency is minimal, allowing differently-abled people to utilize their own evacuation abilities; however, if differently-abled people are unable to evacuate independently and assistance is needed to enhance overall evacuation efficiency, the assistance ratio should be greater than 70%.

For elevator-determined evacuation, adopting unrestricted evacuation on middle floors can enhance evacuation efficiency.

The multi-story building evacuation efficiency analysis model proposed in this paper can clearly determine the optimal evacuation method for each floor. This research can provide insights for the development of emergency evacuation plans for places where differently-abled people reside.

In the design of evacuation plans for five-story buildings, when the assistance ratio is below 40%, it is recommended to use high-level stairwells, mid-high-level elevators, middle-level unrestricted evacuation, and ground-level stairwells for evacuation. When the assistance ratio exceeds 40%, it is recommended to use high-level stairwells, mid-high-level unrestricted evacuation, and middle-level and ground-level stairwells for evacuation.