Optimum Design of the Box Frame Tunnel of the Underground Line Palma-UIB

Transcription

1 X INTERNATIONAL CONGRESS ON PROJECT ENGINEERING Optimum Design of the Box Frame Tunnel of the Underground Line Palma-UIB Perea, Alcalá, Martínez, Yepes (p) and González-Vidosa Group of Methods of Construction, Optimization and Analysis of Structures GPRC Technical University of Valencia Department of Construction Engineering. Spain.

2 Index 1. Introduction 2. Heuristic optimization procedures a. Simulated annealing optimization procedure b. Threshold accepting optimization procedure 3. Optimization of RC road box frames 4. Optimization of Palma- UIB underground tunnel 5. Conclusions

3 Introduction Present design of RC structures is much conditioned by the experience of structural engineers Heuristics methods are a clear alternative to experience: Automatic design Economic optimization Structures: Jenkins (1991) RC: Coello et al. (1997) GPRC (2004) MIN s. a. g i x S ( x) f ( x) 0 R n. i = 1,..., m

4 Introduction Box and portal frames are used with spans between 3 and 20 m Preferred when: Low bearing strength terrain Risk of scour due to flooding Depth of the top and bottom slap: 1/10-1/15 Depth of the walls: 1/12

5 Heuristic optimization procedures Unit Cost ( ) kg of steel (B-500S) m 2 of lower slab formwork m 2 of wall formwork m 2 of upper slab formwork m 3 of scaffolding m 3 of lower slab concrete (labour) m 3 of wall concrete (labour) m 3 of upper slab concrete (labour) m 3 of concrete pump rent m 3 of concrete HA m 3 of concrete HA m 3 of concrete HA m 3 of concrete HA m 3 of concrete HA m 3 of concrete HA m 3 of earth removal m 3 of earth fill-in 4.808

6 Heuristic optimization procedures Working Solution P 0 Current Solution P 1 SA-TA Acceptanc e Criterion Yes No Structural Performan ce Yes No Methodology step 1 Generation of random solutions (random walk) step 2 Study of best moves by descent local search step 3 Calibration of simulated annealing / threshold accepting methods (9 runs per analysis: minimum, mean and standard deviation)

7 Simulated annealing optimization procedure Cost (euros) Cost (euros) Temperature Temperature Time (min)

8 Threshold accepting optimization procedure s 0 ; T i=0 Choose s N(s i ) i=i+1 Stop criteria? YES NO NO f(s )<f(s i )+T? YES s i+1 =s Local optimum s i

9 Feasibility of solutions Loads according to national IAP prescriptions for road bridges ULS SLS Flexure Shear Flexure (cracking control) Deflexions 1/250 for quasipermanent loading Fatigue of concrete

10 Optimization of RC road box frames 44 variables of the RC box frame 2 geometrical values 2 different grades of concrete 40 type of reinforced bars and bar lengths

11 Optimization of RC road box frames Run SA t in sec SA cost in TA t in sec TA cost in R1 30, ,36 15, ,94 R2 27, ,96 15, ,34 R3 26, ,14 15, ,48 R4 26, ,41 17, ,75 R5 30, ,69 15, ,33 R6 32, ,79 16, ,46 R7 32, ,18 17, ,77 R8 24, ,57 17, ,92 R9 25, ,23 13, ,49 MEAN 28, ,59 16, ,28 OPTIMUM DEV, 1,78 2,12 Comparison of results of SA-TA-TS algorithms for case study 1

12 Optimization of RC road box frames 1.5 m of earth cover 1/ /12.34 Optimized design of RC box frame for case study 1 15 seg TA algorithm in a Pentium IV of 2.4 GHz

13 Optimization of Palma- UIB underground tunnel 900 m artificial box tunnel 2. HEURISTIC Horizontal free span of 8.90 m Vertical free span of 6.00 m Earth cover 4.00 m Traffic loading on top RC Concrete ROAD BOX grade of 25 MPa No stirrups in the lateral walls A general spacing of reinforcement of 200 mm Same thickness for the top and bottom slab 5. CONCLUSIONS Cost 3941 /m Savings about 5% Under construction Completed by the end of 2006

14 Optimization of Palma-UIB underground tunnel 1/ m earth cover 1/10.91 Design of 900 m artificial box tunnel Underground Line Palma-UIB

15 Conclusions Structural results have shown to be slender and highly reinforced Span/depth ratio of the top slab = 19 Common values = kg/m 3 in the top slab is high The inclusion of the deflections and fatigue limit states has shown crucial Neglecting them leads 7.9% economic reduction (but unsafe designs) The example of this tunnel shows the practical applicability of the model 3941 /m and savings from tentative design 5%

16 Current and future work Cantilever earth retaining walls Portal road frames Building frames Vaults Abutments of bridges Bridge hollow piers Prestressed concrete slab-decks for flyovers Composite decks for flyovers

17 The authors would like to acknowledge the founding received from the Spanish Ministry of Public Works under research project 80016/A06 Optimum Design of the Box Frame Tunnel of the Underground Line Palma-UIB Perea, Alcalá, Martínez, Yepes (p) and González-Vidosa Group of Methods of Construction, Optimization and Analysis of Structures GPRC Technical University of Valencia Department of Construction Engineering. Spain.