Modeling and optimization of concurrent execution process of coupled design-construction tasks under design-build mode

Concurrent execution of design and construction tasks is an important way to realize the integration of them in design-build (DB) mode, but it may bring about period risk due to multiple rework and frequent information transfer in local scope. To solve this problem, this study constructs a concurrent execution strategy model from the perspective of quantitative analysis with the decision goal of minimizing the total execution duration. The results show that: first, when the probability of information change between design and construction tasks decreases gradually, the optimal overlap degree increases and the optimal parallelism decreases. Second, learning effect can effectively shorten the minimum duration corresponding to the optimal overlap degree under any degree of parallelism. Thirdly, with the decrease of the probability of information change between design and construction tasks and the strengthening of learning effect, the shortening rate of the actual execution duration corresponding to the optimal parallelism will be gradually greater than the increasing rate of the actual execution duration. The findings of the study provide suggestions for exploring the mechanism of concurrent execution in DB mode, and also provide countermeasures for better realization of integration of design and construction in DB mode.