Sivakumar Palaniappan

Special purpose simulation template for workflow analysis in construction

Workflow analysis is an important component in the simulation of construction operations. It involves creating a specific number of work requests for a crew every time period, computing outputs such as work arrival rate for a downstream crew and plotting work in process (WIP). These outputs are not directly provided in many construction simulation software tools. Determining these outputs is generally considered a time consuming and tedious undertaking. Developing modeling constructs that automate the computation of these workflow outputs will be useful for construction modelers. This paper presents a special purpose simulation (SPS) template developed for workflow analysis. The SPS template consists of four modeling constructs that implement the workflow analysis functionalities mentioned above. The SPS template logic was verified using two simulation experiments. Use of this SPS template for analyzing different workflow based issues as well as to test the production management principles in construction is also highlighted.

A Discrete Event Simulation Model to Analyze the Residential Construction Inspection Process

Inspections performed by code enforcement officials (building inspectors of a code enforcing jurisdiction) to confirm building code compliance are an important part of the home building production process. In 2003, an estimated 10 to 15 million code compliance inspections for residential construction were performed in various jurisdictions around the nation. The inspection process and its outcome have a significant impact on all the stakeholders, including city building departments, homebuilders, and trade contractors. This paper focuses on the inspection process in production homebuilding and provides critical analysis via a discrete event simulation model. The design of the simulation model is at the subdivision level and provides a mechanism through which a critical analysis of the process can be performed and waste due to inefficiencies can be identified. The simulation model has been developed in SLAM-II. Input data for the simulation model was obtained from municipal jurisdictions within the Phoenix metropolitan area. Key output parameters include inspection failure rates, impact of failure rates on the production cycle time, and impact of inspection failure on resources provided by individual stakeholders. Even though the model is developed at a subdivision level its results can be extrapolated at the city level and broad conclusions can be drawn.

Carbon Emissions Based on Transportation for Post-Tensioned Slab Foundation Construction: A Production Home Building Study in the Greater Phoenix Arizona Area

There is significant focus on sustainable development of the built environment. Previous studies on sustainable construction have focused primarily upon improving the energy efficiency of buildings during the operational phase, recycling/reuse of building materials, and minimizing wastes. The environmental performance of onsite construction processes is not currently measured or reported as an industry standard practice. Measurement of carbon emissions is one way to understand and improve the environmental performance of onsite construction processes. This study provides an estimation of carbon emissions for transportation in post-tensioned slab foundation construction. Data were collected from a concrete trade contractor and sub-trade contractors in the Greater Phoenix Arizona area. First, carbon emissions are quantified for a typical production home using regional average data. Second, the influence of material and equipment transportation on the relative contribution of trades toward total carbon emissions is quantified. Ready-mix concrete transportation is found to be one of the most significant components and accounts anywhere from 25% to 63% of the total carbon emissions. Third, what-if scenario analysis is presented to study the influence of floor slab size and the travel distance on carbon emissions based on ready-mix concrete supply. Finally, an example is presented to demonstrate the aggregate level impacts.

Modeling construction safety as an agent-based emergent phenomenon

research in construction safety focused on accident data analysis, identification of root cause factors and safety climate modeling. These research efforts did not study the dynamic repetitive interaction among multiple root cause factors. Recently safety research focuses on developing accident causation models. These models attempt to explain how the interaction among multiple project factors gets translated into safety incidents. Agent based modeling and simulation (ABMS) is an appropriate technique to develop computational models of accidents causation because of its ability to model human factors and repetitive decentralized interactions. This paper presents a conceptual framework for developing agent based models of construction safety. The key components of the model such as construction crew, management, work environment, material and equipment related quality issues, project/process level complexities, interaction rules and adaptation have been discussed. Further the adaptation of agents in response to the safety culture has been demonstrated using a simple ABMS experiment

CARBON EMISSIONS OF ON-SITE EQUIPMENT USE IN POST- TENSIONED SLAB FOUNDATION CONSTRUCTION

This paper quantifies carbon emissions due to on-site equipment use in the post-tensioned slab foundation construction process of production homes in Phoenix Arizona. The construction activities performed during post-tensioned slab foundation construction, trades/sub-trades/vendors and the list of construction equipment used for every activity are identified. Data collection involved field visits to several subdivisions, interviews with trades, quantification of use time and the fuel use rate for each equipment as well as the fuel type used for every construction activity. Emissions from fuel consumption were quantified using the guidelines provided by the U.S. Environmental Protection Agency. Analysis of emissions indicates that the concreting trade, the plumbing trade and the grading sub-trade are the three most significant trade components. Activities ‘set floor’, ‘plumbing’, ‘pour floor’ and ‘backfill and grading’ are the four most significant construction activities. Emissions of on-site equipment use are in the range of 4 to 15% of emissions due to transportation. This study is useful for home builders, trade contractors and vendors involved in production home building construction to measure emissions of on-site construction processes, identify significant construction activities and trade components and plan for improvement.

Life cycle energy analysis of a low-cost house in India

ABSTRACT There is tremendous focus in the construction industry to quantify and minimize energy footprint, carbon footprint, material footprint and water footprint and undertake initiatives toward a sustainable built environment. The Economically Weaker Section (EWS)-type residential buildings represent 82% of India’s total housing shortage. It is aimed to meet this housing need by 2022 through the scheme ‘Housing for All’. There is huge demand for materials and energy at the aggregate level and the need for conserving them during the planning, design, construction and operation of residential buildings. This article presents a case study on life cycle energy analysis of a residential building constructed for EWS community in Southern India. Cement, brick and rebar represent more than 3/4th of the total embodied energy of building materials. The structural frame and the building envelope are identified as major hotspots of the total initial embodied energy. The life cycle energy is found to be 0.46 GJ/m2/year for 50 years’ service life. The influence of operation energy and the building service life on the relative significance of construction energy is evaluated. The construction energy represents 29–62% of the life cycle energy for 50 years’ service life.