Modeling Construction Competitive Bidding: An Agent-Based Approach

The construction industry is a complex, multi-level system that includes a large collection of independent, heterogeneous organizations and institutions and is associated with several economic sectors and markets. Because of its unique characteristics, the construction industry as one of the major economic sectors and contributors to the economic development of the nation needs its own specific and dedicated economics. The shortcomings of the existing methodologies call for the use of more sophisticated modeling tools that can capture more important aspects of the real world and its complexity in particular the interconnections among elements of the system, their idiosyncrasies, and emergent behavior. As a pioneer attempt in the exploration of a new theory of construction economics, this study aims to found the first building blocks of the comprehensive economic model of the construction industry. In this dissertation, an agent-based approach is applied to model the low-bid lump-sum construction competitive bidding by which most construction works are allocated. This model has several advantages over the previous analytical and empirical models including the capability of observing the bidding process dynamics, the interaction between the heterogeneous and learning agents, and the emergent bidding patterns arising from multiple scenarios of market conditions and contractors’ attributes. Then the model is used as a virtual laboratory for conducting a variety of experiments to answer several important research questions in the field of construction economics. The main research objectives of this study are to: (1) analyze the effectiveness of major quantitative methods in the bidding environment under a variety of market conditions (2) study the effect of contractors’ risk behavior, cost estimating and project management skills, and complexity of projects on contractors’ choice of optimal markup, long-term financial growth and market share (3) investigate the impact of risk behavior and need for work on contractors’ performance. The results presented in this dissertation offer new understandings and insights on the construction bidding environment and recommendations for both owners and contractors’ competitive success, which are not available using conventional approaches. In particular, results suggest that (1) using Friedman model can result in considerably higher market share whereas using Gates model can result in higher profit per project, (2) the optimal policy for contractors is moderation in both dimensions of risk attitude and need for work, (3) the comparative performance of slightly and extremely risk averse contractors are depending on level of cost estimating accuracy and project execution skills of contractors as well as the level of project complexities

Effective Criteria for Seismic Rehabilitation Planning of Road Transportation Infrastructures

While seismic rehabilitation process for road infrastructures has been traditionally based on seismic factors, consideration of non-seismic factors is necessary for reliable project ranking. Non-seismic factors include socioeconomic criteria, determining the value of a project to its users’ community. Based on the information obtained from a questionnaire survey and literature review, this paper identifies a set of effective rehabilitation criteria (ERC) for seismic rehabilitation decision-making to develop a priority index that is applied to determine the rehabilitation priority. The identified RC will then be weighted for four types of road structures including bridges, tunnels, retaining walls, and buildings. The results can be generalized to provide valuable insights for policy makers concerned with transportation infrastructure planning, especially in developing countries where project prioritization is often an issue. To underline the value of the study, the weighted RC are applied in ranking road rehabilitation projects in an illustrative example

A new class of mixed monotone operators with concavity and applications to fractional differential equations

In this article, we investigate a class of mixed monotone operators with concavity on ordered Banach spaces. As applications, we utilize the main results obtained in this paper to study for solutions of fractional differential equations. An example is also considered to illustrate the main result.Publisher's Versio

Impact of considering need for work and risk on performance of construction contractors: An agent-based approach

Competitive bidding is the main mechanism of allocating projects in the construction market. In the traditional single criterion bidding method, the markup decision has a significant impact on a contractor's business success. Contractors usually take into consideration several factors in the process of determining their markup. This study has reviewed the literature and identified a range of contractors' behaviors when making their markup decision within a competitive bidding environment. An additive markup function consisting of three components, namely competition, risk, and need for work, was developed in order to replicate markup behaviors of contractors. Then, agent-based modeling has been employed for simulating the bidding process within a market formed of a set of heterogeneous contractors with different risk attitudes and defined markup behaviors. This model was used to study the impact of considering need for work and risk allowance in markup determination on financial performance of contractors in various market scenarios. Results suggest that the optimal policy is moderation in both dimensions of risk attitude and need for work

Experimental Study on the Effect of Fibers on Engineered Cementitious Composite Short Square Columns

Recent earthquakes severely damaged short columns due to high lateral stiffness and low ductility. Some conditions, such as reductions in the heights of some columns compared to others on the same floor, deep beams, partially buried basements, and non-structural walls, cause short column effects. The prominent characteristics of engineered cementitious composites (ECCs) reinforced with polyvinyl alcohol (PVA) fibers – including their high tensile strength, micro and multiple cracks, energy dissipation, high ductility, and strain hardening – lead to improved seismic performance and economic efficiency in structure elements. In this study, 11 ECC columns with different fiber fractions (0–1.5%) and aspect ratios (3–7), as well as one conventional concrete column, were tested and evaluated. The results showed that increasing fiber friction and shear aspect ratio increased the length of the plastic hinge zone and ductility by at least 50% and 100%, respectively. Furthermore, the failure mode changed from brittle shear to ductile shear

GENERALIZED BESSEL AND FRAME MEASURES

Considering a finite Borel measure $\mu$ on $\mathbb{R}^d$, a pair of conjugate exponents $p, q$, and a compatible semi-inner product on $L^p(\mu)$, we have introduced $(p,q)$-Bessel and $(p,q)$-frame measures as a generalization of the concepts of Bessel and frame measures. In addition, we have defined the notions of $q$-Bessel sequence and $q$-frame in the semi-inner product space $L^p(\mu)$. Every finite Borel measure $\nu$ is a $(p,q)$-Bessel measure for a finite measure $\mu$. We have constructed a large number of examples of finite measures $\mu$ which admit infinite $(p,q)$-Bessel measures $\nu$. We have showed that if $\nu$ is a $(p,q)$-Bessel/frame measure for $\mu$, then $\nu$ is $\sigma$-finite and it is not unique. In fact, by using the convolutions of probability measures, one can obtain other $(p,q)$-Bessel/frame measures for $\mu$. We have presented a general way of constructing a $(p,q)$-Bessel/frame measure for a given measure

Leisure Questionnaire of People with Multiple Sclerosis

Background: Leisure activities are an important part of life for people with multiple sclerosis )MS). Unfortunately, there are no proper assessment tools for evaluating the leisure activities of MS patients. The current research purposed to develop such a questionnaire and to determine its factor structure.Methods: This psychometric study aimed to determine the factor structure of a questionnaire for evaluating the leisure activities of MS patients and was conducted in explanatory and confirmatory phases.Results: The questionnaire was completed, and the data were entered in SPSS for the explanatory phase and using linear structural relations (LISREL) for the confirmatory phase. The lowest Eigenvalue was 1.01, which corresponds to the Kaiser criterion. The validity coefficients of the extracted factors are considerable. There is a very slight difference between the highest coefficient thatis related to the third factor (0.846) and the lowest coefficient that is related to the fifth factor (0.799), indicating the number of factors was correctly determined. Confirmatory factor analysis illustrated that the goodness-of-fit (GFI) and the comparative fit index (CFI) indices were considerable (higher than 0.95),showing good fit of data. RMSEA was 0.024.Conclusion: It can be concluded that the 5-factor structure (difficult, social,spiritual/religious, outdoor-physical, and cultural-artistic activities) of the multiple sclerosis leisure questionnaire with 50 items is confirmed