JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 2021, VOL. 20, NO. 3, 272–284 https://doi.org/10.1080/13467581.2020.1782918 BUILDING STRUCTURES AND MATERIALS Equivalent uniform live loads under transit vehicles for floor slab of long-span urban transportation hubs a b a,b c Yuhang Li , Yang Deng , Aiqun Li and Peng Sun a b School of Civil Engineering, Southeast University, Nanjing, China; Beijing Advanced Innovation Center for Future Urban Design, Beijing University of Civil Engineering and Architecture, Beijing, China; Department of Civil, Environmental, and Construction Engineering, University of Central Florida, Orlando, FL, USA ABSTRACT ARTICLE HISTORY Received 23 October 2019 Rapid development of long-span urban transportation hubs arouses higher requirements of Accepted 29 May 2020 structural design methods. However, the current design codes do not give effective provisions of the equivalent uniform live load for long-span transportation hubs. A revised equivalent KEYWORDS uniform live load is developed by considering the aspect (length-to-width) ratio of the one-way Long-span slab; heavy- slab system for the urban transportation hubs. The most unfavorable loading positions of the loaded bus; equivalent bus tires are determined, and the equivalent uniform live load is computed by using the uniform live load; urban Chinese Load Code. The structural response under equivalent uniform live load is further transportation hub; aspect ratio compared to that under actual load, then the original equation of the equivalent uniform live load with the Chinese Load Code is revised by considering the aspect ratio of one-way slab. An actual engineering computation of equivalent uniform live load is carried out. The results reveal that the calculation methods of the Chinese Load Code cannot reflect the force transmission characteristics of the small-area tire load on the one-way slab. The structural responses under the revised equivalent uniform load are in good agreement with that under the actual load. The revised calculation method is suitable for most areas in this urban transportation hub and similar structures. 1. Introduction arranging equivalent uniform load according to struc- ture, and they will be introduced in the next three In recent years, with the acceleration of China’s urba- paragraphs. Whichever method is selected, the design nization process and economic development, the vehi- of the hub slab should achieve the balance between cle number is increasing rapidly, and the urban traffic the structural safety and economy (Kamjoo and Eamon congestion is becoming common. To address this 2018; Junyuan, Deng, and Wei 2017). Therefore, the issue, The Central People’s Government of the rational calculation method of the live load for the People’s Republic of China (2013) decided to support urban transportation hub is of great importance in the development of urban transportation hubs that structural design. can integrate bus departure, transfer, parking, and The existing design specifications in national stan- arrangement. In those urban transportation hubs (as dards provide some provisions about the live load of shown in Figure 1), people can park their private cars in buses. ASCE7-16: Minimum Design Loads for Buildings the hub and transfer to the urban core area by buses and Other Structures (ASCE7-16, 2016) proposes the (Clifton et al., 2014; Aixia 2013). The features of such regulations in Tables 4–Table 1. The minimum uniformly urban transportation hub are: (1) the hub is subjected distributed the live load of the garages is 1.92kN/m for to the buses that have a large volume (the length of passenger vehicles only. And for trucks and buses, the the bus is about 18 m) and a large weight (about 27 t); design work should obey AASHTO LRFD Bridge Design (2) the column spacing and the slab span are also Specification (AASHTO 2012). This specification also sti- larger than the usual parking lot buildings. The bus pulates that bus loads are converted to lane line loads. load is the main source of the live load for the urban These national standard methods are not precise and transportation hub, which makes the calculation not suitable for the urban transportation hubs. method of bus load becomes a key issue (Conroy and Eurocode 1: Actions on structures Part1-1: General Tumialan 2015; Keyvani and Sasani 2015). The calcula- actions: Densities, self-weight, imposed loads for build- tion methods of slab system in urban transportation ings (EN1991-1-1, 2002) proposes specification in sec- hub mainly include three methods: arranging uniform tion 6.3.3 of the European Standard. The urban load in the whole area, arranging specific load at the transportation hub can be classified as Category most unfavorable position, and calculating and G. The loads are composed of a single axle load Q (it CONTACT Yang Deng firstname.lastname@example.org Beijing Advanced Innovation Center for Future Urban Design, Beijing University of Civil Engineering and Architecture, Beijing 100044, China © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of the Architectural Institute of Japan, Architectural Institute of Korea and Architectural Society of China. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 273 Figure 1. A prototype of urban transportation hub. Table 1. Dimensions of FE models. a vehicle is 35 kN/m when the one-way slab span is Group Model Length Width Length-width greater than 2 m or the two-way slab span is more than number number (m) (m) ratio 3 m. And the uniform live load of a vehicle is 20 kN/m D1 D1–1 16 5.4 3 D1–2 15 5 3 when the two-way slab span is more than 6 m. When D1–3 14 4.6 3 the above-mentioned conditions are not met, the tire D1–4 12 4 3 D2 D2–1 16 4 4 load of the buses should be converted into an equiva- D2–2 15 3.75 4 lent uniform live load according to the equivalent D2–3 14 3.5 4 D2–4 12 3 4 principle of the structural responses. D3 D3–1 16 3.2 5 The calculation method of equivalent uniform live D3–2 15 3 5 D3–3 14 2.8 5 load has already attracted attentions from researchers. D3–4 12 2.4 5 These studies mainly focus on some factors including D4 D4–1 16 2.7 6 slab span, thickness of cover soil (Le et al., 2018), D4–2 15 2.5 6 D4–3 14 2.4 6 number of buses, the aspect (length-to-width) ratio of D4–4 12 2 6 the two-way slab (Zhong, Hongmei, and Zhonghua 2011), column spacing (Bin, Guodong, and Jimin 2017), and different slab systems (Xin et al. 2019), etc. However, few studies focus on the equivalent uniform may be selected within the range 40 to 90kN) and live load for the slab systems of the urban transporta- a uniformly distributed load q (5.0kN/m ). The axle tion hubs (Duvanovaa, Bubnova, and Romanovich load should be applied to two squares with 2016). Many urban transportation hubs built or under 200 mm×200 mm at the most unfavorable loading construction are still designed by original code positions, and the spacing between two squares is method, however, the applicability of original code 1.8 m. Similarly, the Loading for buildings Part1 Code method is open to doubt. Improper use of calculation of practice for dead and imposed loads (BS6399: Part1: method of equivalent uniform live load may lead to 1996, 1996) proposes that urban transportation hub security risk (Nifu and Haitan 2019; Yang et al. 2018). shall be classified as Category G. The live load should Therefore, it is necessary to propose an improved cal- be determined according to specific use, and the load culation method. is applied on a square contact with a side length of In this paper, the most unfavorable loading posi- 50 mm. These national standard methods are accurate tions of the buses are firstly determined by applying and complicated but not straightforward and suitable different arrangements of the bus loads to slab system for structural designers. in the urban transportation hubs. Then, the structural According to the Chinese Load Code for the design responses under the equivalent uniform live load are of building structures (GB50009-2012, 2012), when the computed according to the current provisions of the vehicle design load is 300 kN, the following rules Chinese Load Code. The calculated responses are com- should be complied. The uniform live load of pared with those under the actual bus loads. Last, the Front Front Front Front 274 Y. LI ET AL. revised equivalent uniform live load calculation on the front axle are 0.2 m × 0.2 m. The long side of the method, which consider the aspect ratio of the one- projection is perpendicular to the driving direction of way slab, is proposed. the BRT, and the short side of the projection is parallel to the driving direction of the BRT. As shown in Figure 2, the spacing between the front axle and the 2. Finite Element (FE) analysis for the most center axle is 6 m; the spacing between the center axle unfavorable arrangement and rear axle is 6.2 m; the transverse spacing of tire groups is 1.8 m; the front and rear spacing between 2.1. Buses loads BRTs is at least 0.8 m; the left and right spacing According to the site investigations in most urban between BRTs is at least 1 m. transportation hubs of China, buses are mainly divided into two types: one is the ordinary bus with a length of 2.2. Most unfavorable loading positions 12 m, and the other is Bus Rapid Transit (BRT) with a length of 18 m. BRT shown in Figure 2 is of interest in According to the Chinese Load Code, the calculation this study. The total weight of the BRT is 280kN, of method of equivalent uniform live load for the slab is which the front axle weighs 65kN, the center axle to convert the bus load with the most unfavorable weighs 100kN, and the rear axle weighs 115kN. loading position into a uniform live load. Due to con- Because the center and rear axles are heavy, one axle struction convenience, the existing urban transporta- of them has two tire groups and one group has two tion hubs of China basically adopt the one-way slab tires side by side, while the front axle has also two tire system. Figure 3 shows a simplified FE model of a one- groups which have only one tire at one end (Figure 2). way slab system in the urban transportation hub. The number of tires mentioned in the article is the A group of one-way slabs compose five one-way number of tire groups. The dimensions of tire projec- slabs whose length are 14.6 m, and width are 2.5 m tion on the center axle and the rear axle are (as shown in Figure 3). The models are established by 0.6 m × 0.2 m, and the dimensions of tire projection using FE package SAP2000. The beams and slabs are Short side of tire Long side of tire 3240 6200 6000 2550 Figure 2. 18 m BRTs size and layout (unit: mm). Note: BRT is the abbreviation of Bus Rapid Transit. Applied load area Slab A Figure 3. FE model (unit: mm). 1800 Front Front JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 275 Front Front Slab A Slab A Center line Center line Stress: 1.32MPa Displacement: 1.18mm Stress: 1.44MPa Displacement: 1.11mm (a) (b) Slab A Slab A Center line Center line Stress: 1.45MPa Stress: 1.93MPa Displacement: 1.67mm Displacement: 1.64mm (c) (d) Front Front Front Front Slab A Center line Center line Stress: 1.00MPa Displacement: 2.20mm Stress: 1.00MPa Slab A Displacement: 2.05mm (e) (f) Figure 4. BRT arrangement and calculation results (unit: mm): (a) Case 1, (b) Case 2, (c) Case 3, (d) Case 4, (e) Case 5, (f) Case 6, (g) Case 7, (h) Case 8, (i) Case 9, (j) Case 10, (k) Case 11. simulated by using beam and shell elements, respec- and eleven cases of BRT arrangements are taken into tively. To reduce boundary effect, there are three spans account. The mid-span bottom stress (tension stress is in each direction in the FE models and the columns are positive) and vertical displacement (downward displa- set as rigid bodies. cement is positive) of slab A are calculated and shown As shown in Figure 4, the loads of one, two, or three in Figure 4. The results indicate that the structural BRTs are applied to one-way slab A in the middle span responses of slab A when the driving direction of the to determine the most unfavorable loading position, BRT parallels to the slab span are more than those 14600 Front Front Front Front Front Front Front Front Front Front 276 Y. LI ET AL. Center line Slab A Stress: 0.43MPa Displacement: 1.08mm Slab A Center line Stress: 2.17MPa Displacement: 3.02mm (g) (h) Slab A Slab A Center line Center line Stress: 2.60MPa Stress: 2.40MPa Displacement: 2.96mm Displacement: 3.92mm (i) (j) Slab A Center line Stress: 2.95MPa Displacement: 3.88mm (k) Figure 4. (Continued). when the driving direction is perpendicular to the slab 3. Calculation method of equivalent uniform span. The structural responses reach the maximum live load in the Chinese Load Code when the rear tires are placed at the intersection of 3.1. Chinese Load Code provisions the two centerlines of the slab. Therefore, Case 4, Case 9, and Case11 are the most unfavorable loading posi- In Chinese Load Code, the equivalent uniform live tions with one (Figure 4(d)), two (Figure 4(i)), and three load for the slab system can be determined according BRTs (Figure 4(k)), respectively. to Appendix C (GB50009-2012, 2012). Since the slab 3240 3240 1750 1750 Front JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 277 systems in the transportation hubs are generally one- where l is the one-way slab span (width). When e is less way slab systems, the equivalent uniform live load than the effective distribution width b, the effective can be calculated according to the Chinese Load distribution width can be written as: Code C0.4 and C0.5, which will be introduced in the b e following. When the driving direction of the BRTs is b ¼ þ (2) 2 2 parallel to the one-way slab width and one tire group is placed at the center point, the structural response is In order to calculate absolute maximum moment (M ), max the largest according to the results in Figure 4. When the one-way slab is simplified as a simply supported one- only one tire group load is applied to the slab, and the way slab and the long sides are the supports. The tire long side of loading projection is perpendicular to the loads are applied to the simply supported one-way slab width (as shown in Figure 5), the effective dis- slab, and M can be calculated through FE analysis. max tribution width should be calculated by using Thus, the equivalent uniform live load q is: Equation (1). In Figure 5, b is the loading projection cx width and b is the loading projection length. 8M cy max q ¼ (3) However, an axle of BRT actually has two groups of bl tires and more than one BRTs are arranged together where b is the effective distribution width of the slab as shown in Figure 4(k). Therefore, the revised effec - and M is absolute maximum bending moment of max tive distribution width is usually calculated by using the simply supported one-way slab. Equation (2) when the spacing between tire groups Four groups of 16 FE models are established to con- are less than the effective distribution width calcu- sider different aspect ratios. Each FE model group has the lated by Equation (1) (as shown in Figure 6). same aspect ratio, the dimensions of the FE models are The calculation procedures according to the shown in Table 1. The length of slab in the urban trans- Chinese Load Code are as follows: portation hub usually more than 10 m, therefore, three The effective distribution width b of the tire load on buses can be placed on the slab at the most unfavorable the one-way slab is: positions to obtain the equivalent uniform live load and the corresponding structural response, as shown in b ¼ b þ 0:73l (1) cy Figure 7. Figure 5. Effective distribution width under a tire load. Figure 6. Effective distribution width under adjacent local loads. 278 Y. LI ET AL. Figure 7. Tires arrangement at the most unfavorable loading position. Code are applied to the models listed in Table 1. The 3.2. Results of equivalent uniform live loads mid-span stress and the mid-span vertical displace- The effective distribution width, absolute maximum ment are obtained by FE analysis. The results from bending moment, and equivalent uniform live load of Figure 10 indicate that the mid-span stress under the each slab can be obtained according to the previously actual loads decreases with the increase of the aspect mentioned equations. Two or more BRTs are arranged ratio, and the mid-span stress under the equivalent side by side, thus the effective distributed width (as uniform load increases with the increase of aspect shown in Figure 6) is only related to the spacing of groups ratio. The mid-span stress of the equivalent uniform of tires. For example, there are six groups of tires on the load is less than that of the actual load, which means slab (Figure 7). One group of tires is in the centerline of unsafe. slab, and another group of tires in the same BRT is 1.8 m The mid-span vertical displacement under the away from it, while the group of tires in another BRT is actual tire load decreases slightly with the increase of 1.75 m away from it. The effective distribution width is the aspect ratio, and the mid-span vertical displace- 1.775 m as shown in Figure 7, and the effective distribu- ment of the slab under equivalent uniform live load is tion width of all FE models in Table 1 is similarly less related to the aspect ratio. The mid-span vertical a constant of which the value is 1.775 m. As shown in displacement is greatly related to the slab length, but Figure 8, the absolute maximum bending moment slightly related to the aspect ratio. approximately increases with the increase of slab span, The main reasons for the results from Figure 10 are while the calculated equivalent uniform load decreases as follows: (1) the actual tire load is applied to small with the slab span increasing (as shown in Figure 9). area around tire, but the structural responses under Both actual loads of the BRT tires and equivalent the actual tire load is extremely large. (2) According to uniform live loads calculated by the Chinese Load Equation (3), the effective distribution width leads to D1-1 D1-2 D1-3 D1-4 D2-1 D2-2 D2-3 D2-4 D3-1 D3-2 D3-3 D3-4 D4-1 D4-2 D4-3 D4-4 Model number Figure 8. Absolute maximum bending moment calculated by the Chinese Load Code. Absolute maximum bending moment (kN·m) JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 279 D1-1 D1-2 D1-3 D1-4 D2-1 D2-2 D2-3 D2-4 D3-1 D3-2 D3-3 D3-4 D4-1 D4-2 D4-3 D4-4 Model number Figure 9. Equivalent uniform live load calculated by Chinese Load Code. (a) Actual load Equivalent load D1-1 D1-2 D1-3 D1-4 D2-1 D2-2 D2-3 D2-4 D3-1 D3-2 D3-3 D3-4 D4-1 D4-2 D4-3 D4-4 Model number (b) Actual load Equivalent load D1-1 D1-2 D1-3 D1-4 D2-1 D2-2 D2-3 D2-4 D3-1 D3-2 D3-3 D3-4 D4-1 D4-2 D4-3 D4-4 Model number Figure 10. Comparison of structural response under actual load and equivalent uniform live load: (a) Mid-span stress, (b) Mid-span vertical displacement. the decrease of the equivalent uniform live load. (3) 4. Equivalent uniform live load with an aspect The equivalent uniform live load increases with the ratio aspect ratio increasing, resulting in an increase of mid- 4.1. Revised equivalent uniform live load span stress. However, the structural responses under the actual load may decrease with the aspect ratio Equation (3) reveals that the equivalent uniform live increasing because the loading diffusion effect gets load calculated by the current Chinese Load Code is bigger with the aspect ratio. only related to the span of the one-way slab. To prove It can be concluded that structural responses under that the structural response under the BRTs’ tire load is the equivalent uniform live load based on the current related to the length of slab, four one-way slab models Chinese Load Code is lower than that under the actual with the same width and different lengths are estab- load. This may result in an unsafe design of the slab lished, shown in Figure 11. The same tire load is system, and is not suitable for the slab design of urban applied to the mid-span of the middle slab in the transportation hubs. four models in Figure 11. Equivalent uniform live load (mm) Vertical displacement Mid-span stress (MPa) (kN·m- ) 280 Y. LI ET AL. (a) (b) Main beam Main beam Secondary beam Secondary beam Tire load Tire load Center line Center line 3000 3000 3000 3000 3000 3000 3000 3000 3000 3000 3000 Mid-span maximum stress: 2.40MPa Mid-span maximum stress: 2.32MPa Mid-span vertical displacement: 2.13mm Mid-span vertical displacement: 1.50mm (c) (d) Main beam Secondary beam Secondary beam Main beam Tire load Tire load Center line Center line 3000 3000 3000 3000 3000 3000 3000 Mid-span maximum stress: 2.22MPa Mid-span maximum stress 2.12MPa Mid-span vertical displacement: 0.93mm Mid-span vertical displacement: 0.59mm Figure 11. Structural arrangement of different lengths of the one-way slab and the structural response under the tire load: (a) 18 m one-way slab, (b) 15 m one-way slab, (c) 12 m one-way slab, (d) 9 m one-way slab. (unit: mm). The structural responses in Figure 11 reveal that the As shown in Figure 12, the selected strip under the mid-span bottom stress decreases with the decrease of local tire load can be equivalent to a simply supported the length of the one-way slab. The current Chinese beam. A local uniformly distributed live load is applied Load Code cannot effectively consider the effects of to the middle of the simply supported beam. The the one-way slab length, and it will lead to inaccurate absolute maximum bending moment of the beam is: results. Therefore, the revised equivalent uniform live � � 1 1 b cx load is proposed in this research. The detailed proce- M ¼ qb b l qb (4) max cy cx cy 4 2 2 dures of the revised calculation method are as follows: The effective distribution width can be still deter- where q is wheel distributed uniform load. mined based on the current provision in the Chinese Then, the relationship between the coefficient α Load Code. (α = q bl/8M ) and the aspect ratio is investigated. e max Simply support cx Short side of tire b cx Tire line load Simply supported beam Selected strip One way slab span l Tire distributed uniform load q note Tire line load= Tire distributed uniform load q Long side of tire b cy Figure 12. Calculation diagram of absolute maximum bending moment. 9000 15000 JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 281 1.2 where l is the span of the slab; b the effective distribu- tion width of load on the slab, calculated by Equation 1.1 (1) or Equation (2). -0.289 α= 1.4736ξ 0.9 4.2. Structural responses under revised equivalent uniform live loads 0.8 The structural responses under the revised equivalent 0.7 uniform live load of the models in Table 1 are calcu- lated. The effective distribution width is still a constant 0.6 2 3 4 5 6 7 of which the value is 1.775 m. Then, the absolute maximum bending moment and equivalent uniform live load are calculated by using Equations (4), (5) and Figure 13. Fitting of α and the length-width ratio. (6), respectively. The structural responses under the actual load and the revised equivalent uniform load b and M are obtained in Equation (1)/(2) and max are shown in Figure 14. Equation (4), respectively. q is determined by the The discussions can be made on the results from actual situation according to the equivalent principle Figure 14 as follows. (1) The mid-span slab stress of the of structural response. Figure 13 shows a scatter plot of revised equivalent uniform live load is in excellent α and ξ (the aspect ratio). A proper curve is selected to agreement with the actual load, and the structural model the relationship shown in the figure. The envel- response decreases with the increase of aspect ratio. oping curve is mathematically expressed as: In addition, the stress under the revised equivalent uniform live load is slightly more than that under the 0:289 α ¼ 1:474� (5) actual load. (2) The mid-span vertical displacements caused by both actual load and revised equivalent where ξ is the aspect ratio of a one-way slab. uniform load decrease with the increase of aspect Thus, Equation (3) could be rewritten as: ratio. 8M max The reasons for the results are as follows. (1) The q ¼ α (6) bl revised calculation method of absolute maximum (a) Actual load Equivalent load D1-1 D1-2 D1-3 D1-4 D2-1 D2-2 D2-3 D2-4 D3-1 D3-2 D3-3 D3-4 D4-1 D4-2 D4-3 D4-4 Model number (b) Actual load Equivalent load D1-1 D1-2 D1-3 D1-4 D2-1 D2-2 D2-3 D2-4 D3-1 D3-2 D3-3 D3-4 D4-1 D4-2 D4-3 D4-4 Model number Figure 14. Comparison of structural response under actual load and revised equivalent uniform live load: (a) Mid-span stress, (b) Mid-span vertical displacement. Vertical displacement (mm) Mid-span stress (MPa) 282 Y. LI ET AL. bending moment considers the features of the tire highlighted within the red-colored rectangles in load. (2) The revised equivalent uniform live load con- Figure 15. siders the influence of the aspect ratio of the one-way The effective distribution width, the absolute slab system. Hence, the revised method developed in maximum bending moment, the coefficient α and this research can accurately calculate the equivalent equivalent uniform live load of the urban transpor- uniform live load for the one-way slab systems of the tation hub slabs are calculated by using Equations urban transportation hubs. (2), (4), (5) and (6), respectively. Table 2 lists the results. Then, the revised equivalent uniform live load is applied to the slab system of a real urban 5. Verification of actual engineering transportation hub. The mid-span stress and vertical displacement under the revised equivalent uniform The revised equivalent uniform live load considering live load are compared with the structural the aspect ratio has been proposed above. However, responses under the actual load. The results of the aforementioned layout of structures in Table 1 are Figure 16 reveal that the structural responses relatively simple compared to a real urban transporta- under the revised equivalent uniform load with tion hub. Therefore, the structural response of a real the aspect ratio are in good agreement with the urban transportation hub is calculated to verify the structural responses under actual load. The revised accuracy of the revised calculation method. A central equivalent uniform live load has no relationship area and a boundary area are chosen from the slab with the location of the concerned slab areas. system of the real structure. The chosen areas are Central area Boundary area Applied load area Applied load area Figure 15. Slabs in the central and boundary area (unit: mm). JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 283 Table 2. Slab load parameters. Dimension Length-width Effective distributed Absolute maximum bending Equivalent uniform load −2 Area (m × m) ratio width (m) moment(kN·m) α (kN·m ) Central area 14.6 × 2.5 5.84 1.78 34.50 0.885 21.96 Boundary 16.2 × 2.5 6.48 1.78 34.50 0.859 21.31 area (a) (b) Actual load Actual load Equivalent load 10 Equivalent load 0 0 Central area Boundary area Central area Boundary area Selected area Selected area Figure 16. Comparison of structural response under actual load and revised equivalent uniform live load in central and boundary area: (a) Mid-span slab stress, (b) Slab vertical displacement. As mentioned in section 2.2, the most of the urban (4) The actual engineering verification shows that transportation hubs in China used the one-way slab the revised calculation method can apply to the system. This paper aims to provide a revised equivalent slab whether in the middle or edge of urban trans- uniform live load for the one-way slab system. It should portation hub. The revised equivalent uniform live be noted that for the two-way slab system, the equiva- load is suitable and efficient for the design of slab lent uniform live load needs further investigation. system in the urban transportation hub and similar structures. 6. Conclusions Disclosure statement This paper presented a revised equivalent uniform live load considering the aspect ratio of one-way slab sys- No potential conflict of interest was reported by the authors. tem for the urban transportation hubs. The main con- clusions could be drawn as follows: Funding (1) The calculation method of equivalent uniform live Supports from the National Natural Science Foundation of load is simpler than the method of arranging specific China under Grant No. 51878027, National Key Research and load at the most unfavorable loading position, and is Development Project under Grant No.2017YFC0703602, more accuracy than the method of arranging uniform General Project of Beijing Municipal Education Commission load in the whole area. Therefore, the equivalent uni- under Grant No. KM201910016013 and Youth talent support form load method is a useful and effective. program of Beijing Municipal Education Commission under (2) The absolute maximum bending moment calcu- Grant No. CIT&TCD201904060 are gratefully acknowledged. lated by the current Chinese Load Code is not suffi - cient to reflect the force transmission characteristics of the small-area tire load on the one-way slab. The Notes on contributors Chinese Load Code does not consider the effect of the one-way slab length, so the structural response Yuhang Li is a Ph.D. student and his principal research inter- under the equivalent uniform live load of Chinese ests include seismic and wind-resistant of civil engineering Load Code is smaller than that under actual load. structures, etc. (3) According to the force transmission characteristics Yang Deng is a Professor and his principal research interests of urban transportation hub slab, the revised equiva- include structural health monitoring, etc. lent uniform load is proposed considering the aspect Aiqun Li is a Professor and his principal research interests ratio of the one-way slab system. The structural include seismic and wind-resistant and seismic isolation of responses under the revised equivalent uniform live civil engineering structures, new engineering structure sys- load are in good agreement with those under the tem, structural health monitoring and safety assessment, etc. actual load. The results also indicate that the revised equivalent uniform live load method can balance the Peng Sun is an Assistant Professor and his principal research structural safety and economic cost. interests include structural health monitoring, etc. Mid-span stress (MPa) Vertical displacement (mm) 284 Y. LI ET AL. ORCID EN 1991- 1-1. 2002. “Eurocode1: Actions on Structures – Part1-1: General Actions - Densities, Self-weight, Imposed Yang Deng http://orcid.org/0000-0001-5807-1440 Loads for Buildings”. GB50009-2012. 2012. “Load Code for the Design of Building Structures”. (in Chinese) Junyuan, Y., L. Deng, and H. 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Journal of Asian Architecture and Building Engineering
– Taylor & Francis
Published: May 4, 2021
Keywords: Long-span slab; heavy-loaded bus; equivalent uniform live load; urban transportation hub; aspect ratio