icccbe2010© Nottingham University PressProceedings of the International Conference on Computing in Civil and Building Engineering W Tizani (Editor)

Abstract Building performance-based design usually includes structural, fire and energy performance assessment. Currently performance simulation is mostly carried out at the end of the design stage and thus not integrated into design decision-making. Building Information Model (BIM) stored multi-disciplinary data could greatly simplify and execute the performance-based design at the preliminary and detailed design stages. An integrated BIM design platform was established based on AutoCAD Architecture (ACA). In addition to the general design software the platform was integrated with structure, fire and energy analysis codes including the elastic-plastic time history earthquake analysis code ABAQUS, energy analysis code EnergyPlus, Computational Fluid Dynamics code StarCD and etc. The platform extracted the necessary model data and parameters from BIM to corresponding performance-based analysis code and activated the computational procedures automatically on the server computers. The relative results were returned to ACA platform and formed graphical visualization. The platform took the advantages of BIM and greatly improved the design quality and efficiency in practice.

Keywords: BIM, performance-based analysis, earthquake analysis, energy analysis, CFD, design

1 Overview A lot of buildings with complex shapes and structures have been emerged in China’s Olympic Games, World Expo and other international events. For these kinds of building traditional design methodologies have a lot of limitations. And performance-based analysis and design methods could help designers overtake the challenges and achieve efficient, safe and environmentally friendly designing.

Performance-based design is a need-based designing method for safe, comfortable, economy and some other performance criteria. Designers need to work in different subsystems with different performance indexes, including the goals on architecture, structures and environment, and cooperate to achieve the established goals (Francoise 2005, Iwasaki 1997 and Dillenboijrg 1995).

Building performance-based design usually includes structural, fire and energy performance assessment. Currently performance simulation is mostly carried out at the end of the design stage and thus not integrated into design decision-making. Building Information Model (BIM) stored multi-disciplinary data could greatly simplify and execute the performance-based design at the preliminary and detailed design stages. An integrated BIM design platform was established based on AutoCAD Architecture (ACA).In addition to the general design software the platform was integrated with architecture, structure, fire and energy analysis codes including parametric modeling code CATIA,

Performance analysis and design platform based on BuildingInformation Model

Wang Guo-jian Shanghai Xiandai Architectural Design (Group) Co.,Ltd. , Shanghai, China

Wang Cong-jun & Zhang Xin Shanghai CAD Simula Design Technologies Co.,Ltd., Shanghai, China

in-house curtain wall generation code, the elastic-plastic time history earthquake analysis code ABAQUS, energy analysis code Energyplus and DOE2, Computational Fluid Dynamics code StarCD and etc. The platform extracted the necessary model data and parameters from BIM to corresponding performance-based analysis code and activated the computational procedures automatically on the server computers.

2 Performance-based analysis platform architecture

2.1 Concept of performance-based analysis platform Traditional design methods are usually based on design standards for the drawing and specification. For performance-based design designers take a series of performance criteria, functional design and a lot of advanced analytical tools to help decision-making in the various stages of designing. The work flow of performance-based design is shown in Figure 1. The multiple way of comparison between performance criteria and performance evaluation would help to reach consensus, which involves a large number of analysis. In performance-based design the following performances are usually considered. (1) Comfort, which includes temperature, air quality and noise (2) Security, which includes typhoons, earthquakes, fire and emergency evacuation. (3) Economy, which includes material, cost, operation and maintenance plans. (4) Environment, which includes energy consumption, air pollution, sunlight, solar. (5) Architecture, which includes residential planning, curtain wall Building design usually includes conceptual design, preliminary design and construction design. During the stage of conception and preliminary design the consideration on the performance is critical, which would involve the work on design process and revision. So the performance-based analysis would provide the important reference on the decision-making. (Sun 2003, Lam 2001 and Lam 2002) Performance-based analysis involves different types of problems, some of which are related. The integrated platform with a variety of codes including in-house codes could improve the efficiency of analysis and hardware in the enterprise. The integrated platform could shorten the design cycle, reduce the costs and improve the design quality and capabilities.

Figure 1. Concept of performance-based design

2.2 Performance-based analysis platform Overall performance-based analysis technique in China at present is still in its infancy. Performance-based assessment indicators are still at the exploratory stage. A variety of performance-based analysis solutions are still under development. Performance-based analysis relates to the multi-disciplinary engineering fields and professional calculation and analysis. Integrated simulation environment could quickly perform a variety of analysis, to provide references for rapid decision-making. If performance-based analysis is combined with optimization algorithms and tools, it is also able to achieve some functions of the auto-optimization and design optimization. The performance-based analysis platform packages various disciplines analysis software into reusable components, which can be implemented in an integrated environment. Through the task manager to complete analytical tasks by multiple CPUs, multiple computers distributed deployment, perform parallel computing to achieve performance-based analysis of the various disciplines to work together. Optimization and comparison of different proposals in the phase of preliminary architectural design is a very complex system engineering, to use parametric modeling, optimizing processes, the various disciplines professional software to analyze and automatically analyze the key results. At present the platform integrates many commercial CAD / CAE / CFD and professional software, including the ACA / AutoCAD / CATIA、FEM(ANSYS/ABAQUS/SDT)、 MESH(HYPEMESH) 、DATA(MATLAB)、 CFD(STAR CD) 、Professional Software (Energyplus/DOE2) and so on. At the same time it integrates a number of self-compiled software,

Figure 2. Performance-based analysis platform

Through the development and integration technology the platform has the following characteristics: （1）The platform could help get the best analysis process. Each experienced professional analyst has his own working process in their mind. But perhaps we never considered what kind of process is the best? Through the development of automation process it can be sorted out and saved by a set of best processes and records. （2）The analysis processes could be standardized. The platform tool could help fix the processes and form a standard set of processes. （3）The platform could help improve analysis efficiency and accuracy. The computer could automatically complete a lot of repetitive manual work, free the designers to engage in other more meaningful work, and reduce simple mistakes in their manual operation. Through automated processes for analysis platform the time required for manual operation could probably be shorten by 50% -80%. （4）The platform could help reduce the loss of experience and the time to train new employees. Many companies have some problem with new engineers’ training, and are faced with job-hopping problem

when the employees can independently take up work. Through customization process on the integrated platform we can greatly reduce the loss of experience and shorten the time to train new employees.

3 Case study

3.1 Curtain wall of high-rise building Wuhan Center will be 428 meters height. The outer walls are all the complex curved surfaces. The performance-based analysis is used to support the decision-making in the early stages of architecture design. Using CATIA’s parametric modeling technology, the arbitrary curved of surface could be described using a few characteristic parameters. Based on the functional requirement we could bind several key parameters. The architects can adjust other parameters to create the different shapes, plan and facade. It makes the architects’ workload of modeling be reduced greatly. The parameterized geometrical model is shown in Figure 4. Outer surface includes building wall surface and curtain wall surface. The key points on the curtain wall are determined on the basis of the geometric characteristics and used as the constraints for analysis. We can create a regular distribution of control points using the numerical calculation method, which seeks to evenly distribution. The control points are treated as the intersection point of the glass wall. Due to large amount of calculating the coordinates of control points we need to complete the work by writing a computer program instead of by hand. After coordinates of the control nodes on wall surface are generated, four nodes are connected to form rectangular surface and visualize the results by AutoCAD development codes. Based on the statistics for all classified curtain wall designers can adjust key points or other constraints according to the difficulty of manufacturing and construction of curtain wall, and compare the results of multiple programs by repeating computation, to obtain the most optimal way of dividing curtain wall. If it’s necessary designers need to adjust building shape. The performance-based design work flow for shaping the building is shown in Figure 3.

Figure 3. Performance-based design process of building outer surface

Figure 4. Parameterized geometric （a）Curtain A (b) Curtain B model of high-rise building Figure 5. Dividing scheme of curtain wall

Table 1. Statistics result of curtain walls

Curtain A Curtain B Size Deflection Amount Size Deflection Amount

1200×4200 0.003 3940 1200×4200 0.003 3940 1200×5000 0.002 182 1200×5000 0.002 182 1200×6200 0.002 126 1200×6200 0.002 126 700×4200 0.01 50 800×4200 0.01 75 400×4200 0.15 30 400×4200 0.01 5

Yes

No

CATIA Three-dimensional

surface model

Determine the key points of shape (Constraints)

Numerical calculation of wall division

Statistical result of wall division

Convenience of manufacturing and construction

Determine curtain wall division, realize visualization results by in-house program

Determine building shape

The main parameters on the model of Wuhan Center are the surface radius (R1 and R2), which are shown in Figure 4. By adjusting the value of R1 and R2, the division output result of curtain walls could evaluate from various programs. The program’s performance requirements have two aspects. (1) The deflection of each curtain wall doesn’t exceed 0.01. (2) The types of curtain wall are at minimum. The examples of division program and statistical results are shown in Figure 5 and Table 1. Through comparison of different diameters and dividing scheme designers could get the optimal building model with curtain wall division.

3.2 Structural analysis Design theory of seismic resistance of structure experienced four phases, including static design, response spectrum design, dynamic design and vibration control design. The current seismic design in the world is based on deformation of the structures under the seismic beyond the probability of different levels. The elastic-plastic time history earthquake analysis becomes necessary during the seismic design. Earthquake-resistant design comes into a truly age of dynamic analysis. Performance-based seismic design concept aims to meet the various pre-set performance targets and requirements during the usage of engineering structures. Seismic response of building structures is not only to ensure safety, but also to ensure that the minimum economic loss in the context of design of expected requirement, which is a kind of design method to control the response of building structure and damage. Elastic-plastic time-history analysis can predict the losses of structure under earthquake. The structural design can help strengthen the weak part of the structures, achieve better construction safety performance and reduce life-cycle maintenance costs. Table 2 shows the levels of performance indicators for a high-rise building with the height of 180 meters, shown in fig.6. After accomplishing elastic-plastic analysis we found the main wall was not apparently damaged.

Figure 6. A residential high-rise building and elastic-plastic time-history analysis results under strong earthquakes

Table 2. Definition of level performance Capacity level Performance Level Good usage Harmless Safety No Collapse Collapse Extent of damage No damage A little Medium Serious Totally damage Index of damage 9-10 7-8 5-6 3-4 1-2 Limit of instantaneous inter-story deformation <0.2% <0.5% <1.5% <2.5% >2.5% Limit of permanent inter-story deformation — — <0.5% <2.5% >2.5%

3.3 Energy We simulated the annual energy consumption of a shopping mall construction on the platform. After survey we got the distribution law of the local energy conservation parameter (including construction orientation, ratio of window to wall area, shape factor, the external retaining of the structure construction and some other aspects). Using DOE-2 to simulate the energy consumption status, the results show that the local energy consumption status generally exceeding the demand of The Energy-saving Design Standards. After a large number of simulations, we detailed analyzed affecting laws of the orientation, shape coefficient, the performance to the structure external retaining to the various types of building air conditioner energy consumption, and get the difference rate between the best orientation and worst orientation varies from 0.08% to 6.00%. The shape coefficient has little effect to the air conditioner energy consumption of the building. External walls, roof, and windows in different building type have different contribution rate of energy-saving. Finally based on the results of a large number of simulations we proposed to use efficient and energy-saving design programs to the architects.

Figure 7. Energy Analysis Model of Shopping Mall

Figure 8. Results of Energy Analysis

3.4 CFD Analysis Wind-resistant design is one of the great challenges in the high-rise building design. The wind loads is one of the main effect factors in the design of the main structures and curtain wall. Structural design must consider the wind-along direction and crosswind response of the structures, and also consider the living comfort under the dynamic wind loads. Meanwhile, the numerical results of the calculation can be used for shape optimal design of curtain walls.

Wind-resistant design applications by numerical wind tunnel test on the high-rise building mainly include: (1) Providing the shape coefficient of wind loads for optimizing the outer shape of the building in the preliminary design; (2)Providing the wind loads for the designing of curtain walls; (3) Providing the wind loads for the cantilevered member of the building; (4) Considering the wind environment impact from the neighbor buildings; (5) Estimating the living comfort under strong wind; (6) Assessing the pedestrian comfort at the construction vicinity. The numerical wind tunnel model of the ultra high-rise building named Wuhan Center was made according to the actual size of the structure. By using CFD calculation we got the pressures on each point of the building, which could be used to design the structure and curtain walls. By Unsteady Reynolds-Averaged Navier-Stokes method we got the unsteady base forces of the whole building. For Fig.9 we can see the main period of vortex shedding from the building is about 8s. So the natural vibration period of structure should avoid 8s.

Figure 9. Wind pressure coefficient distribution on Building surface and base shear time history

4 Conclusion The performance-based analysis has played an increasingly important role in the phase of buildings’ conceptual design, including sunlight, energy-saving, typhoon, earthquake, fire, air pollution, temperature and humidity, noise, cost, curtain walls and other performance-based analysis. Based on the AutoCAD Architecture models, we can complete some performance-based analysis by performance-based analysis platform. Combining performance-based indicators, we completed part of the performance-based design, and provided design assistance to architects, and played a certain role in a number of projects. As the platform functions get richer, performance-based analytical platform will be provide greater benefits in the stage of design.

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