The effect of polypropylene fibres within concrete with regard to fire performance in structures

Purpose – The purpose of this paper is to examine the effect of various polypropylene fibre additions (types and volume) to concrete with regard to explosive spalling when subject to high temperatures similar to those experienced in building or tunnel fires. Design/methodology/approach – Medium strength concrete was manufactured with varying proportions of polypropylene fibres. Plain control samples were used to determine the original concrete strength and this was used as a benchmark following high temperature heat tests to evaluate the surface condition and final compressive strength. A pilot study was used to determine an appropriate heat source for the test. This was three Bunsen burners, however sufficient heat could not be generated within 150mm concrete cubes and the concrete was shown to be a significant insulator and fire protection for structural members. The concrete test cubes were tested in a saturated condition which may reflect conditions where concrete is used in an external environment and thus is subject to soaking. Findings – One hundred and fifty millimetre concrete cubes with and without fibres were placed into a furnace at 1,000°C. Explosive spalling was shown to be reduced with the use of polypropylene fibres but the final compressive strength of concrete was significantly reduced and had little residual structural value after a two hour period of heating. Research limitations/implications – As the concrete tested was saturated, this condition provided a worst case scenario with regards to the build up of hydrostatic and vapour pressure within the cube. A range of percentage moisture contents would produce a more evenly balanced view of the effects of fibres in concrete. A single grade of concrete was used for the test. As the permeability of concrete influences the rate at which steam can escape from the interior of a saturated concrete cube, testing a range of concrete strengths would show this aspect of material performance with regard to spalling and final residual strength. Further research is recommended with regard to moisture contents, strengths of concrete and a range of temperatures

Multilateral, Regional, and Bilateral Trade-Policy Options for the United States and Japan

We have used the Michigan Model of World Production and Trade to simulate the economic effects on the United States, Japan, and other major trading countries/regions of a prospective new round of WTO multilateral trade negotiations and a variety of regional/bilateral free trade agreements (FTAs) involving the United States and Japan. We estimate that an assumed reduction of post-Uruguay Round tariffs on agricultural and industrial products and services barriers by 33 percent in a new WTO trade round would increase world welfare by $613.0 billion, with gains of$177.3 billion for the United States, $123.7 billion for Japan, and significant gains for all other industrialized and developing countries/regions. If there were global free trade with all post-Uruguay Round trade barriers completely removed, world welfare would increase by$1.9 trillion, with gains of $537.2 billion (5.9 percent of GNP) for the United States and$374.8 billion (5.8 percent of GNP) for Japan. Regional agreements such as an APEC FTA, an ASEAN Plus 3 FTA, and a Western Hemisphere FTA would increase global and member country welfare but much less so than a new WTO multilateral trade round would. Separate bilateral FTAs involving Japan with Singapore, Mexico, Chile, and Korea and the United States with Chile, Singapore, and Korea would have positive, though generally small, welfare effects on the partner countries, but potentially disruptive sectoral employment shifts in some countries. There would be trade diversion and detrimental welfare effects on some nonmember countries for both the regional and bilateral FTAs analyzed. The welfare gains from multilateral trade liberalization are therefore considerably greater than the gains from preferential trading arrangements and more uniformly positive for all countries.

Developing Countries' Stake in the Doha Round

In this paper we discuss the various aspects of the Doha Round of Multilateral Trade Negotiations in the WTO that offer potential benefits for developing countries. We then use the Michigan Model of World Production and Trade to simulate the economic effects on the major trading countries/regions of the reductions in tariffs, subsidies in agriculture, and barriers in services that may be negotiated in the Doha Round, as well as a variety of regional free trade agreements (FTAs). We estimate that an assumed reduction of post-Uruguay Round tariffs and other barriers on agricultural and industrial products and services by 33 percent in the Doha Round would increase world welfare by $686.4 billion, with significant gains for all industrialized and developing countries/regions. Regional agreements such as an APEC FTA, an ASEAN Plus 3 FTA, and a Western Hemisphere FTA would increase global and member country welfare, but by much less than the Doha multilateral trade round. There would also be trade diversion and detrimental welfare effects on some nonmember countries for the FTAs analyzed. The welfare gains from multilateral trade liberalization are therefore considerably greater than the gains from preferential trading arrangements and more uniformly positive for all countries.WTO, Trade Liberalization

CGE Modeling and Analysis of Multilateral and Regional Negotiating Options

We have used the Michigan Model of World Production and Trade to simulate the economic effects on the United States, Japan, and other major trading countries/regions of: the Uruguay Round of multilateral trade negotiations completed in 1993-94; a prospective new round of WTO multilateral trade negotiations; and a variety of regional/bilateral free trade agreements (FTAs) involving the United States and Japan. We estimate that the Uruguay Round negotiations increased global economic welfare by $75.1 billion annually, with gains of$12.9 billion for the United States and $15.6 billion for Japan. An assumed reduction of all post-Uruguay Round tariffs on agricultural and industrial products and of all services barriers by 33 percent in a new WTO trade round is estimated to increase world welfare by$613.0 billion, with gains of $177.3 billion for the United States and$123.7 billion for Japan. If there were global free trade with all post-Uruguay Round trade barriers completely removed, then world welfare would increase by $1.9 trillion, with gains of$537.2 billion (5.9 percent of GNP) for the United States and $374.8 billion (5.8 percent of GNP) for Japan. Elimination of APEC-member country bilateral post-Uruguay Round tariffs on agricultural and industrial products and services barriers is estimated to increase world welfare by$764.4 billion, with gains of $294.7 billion for the United States and$283.1 billion for Japan and losses of $7.0 billion for the European Union/EFTA and$1.0 billion for South Asia. Separate bilateral FTAs involving Japan with Singapore, Mexico, South Korea, and Chile and an ASEAN Plus-3 FTA involving Japan, China/Hong Kong, and South Korea would have positive, though generally small, welfare effects, but potentially disruptive sectoral employment shifts in some member countries. Depending on the agreement, there may be detrimental welfare effects on some nonmembers. The welfare gains from multilateral trade liberalization are therefore considerably greater than the gains from preferential trading arrangements and more uniformly positive for all countries.

Impacts on NAFTA Members of Multilateral and Regional Trading Arrangements and Initiatives and Harmonization of NAFTA's External Tariffs

We have used the Michigan Model of World Production and Trade to simulate the economic effects on the NAFTA member countries and other major trading countries/regions of a prospective new round of WTO multilateral trade negotiations, the variety of free trade agreements (FTAs) that the NAFTA members have negotiated or are considering, and the adoption of a system of common external tariffs by the NAFTA members. We estimate that an assumed reduction of post-Uruguay Round tariffs on agricultural and industrial products and services barriers by 33 percent in a new WTO trade round would increase world welfare by $613.0 billion, with gains of$177.3 billion for the United States, $13.5 billion for Canada,$6.5 billion for Mexico, and significant gains for all other industrialized and developing countries. If there were global free trade, world welfare would increase three-fold to $1.9 trillion and the country/region gains would be similarly larger. Regional FTAs such as an expansion of NAFTA to include Chile and a Western Hemisphere FTA would increase global and member-country welfare but much less than a new WTO multilateral trade round would. Separate bilateral FTAs negotiated or being considered by Canada, Mexico, and the United States would have positive, though generally small, welfare effects on the partner countries, but potentially disruptive sectoral employment shifts in some countries. There would be trade diversion and detrimental welfare effects on some nonmember countries for both the regional and bilateral FTAs analyzed. If the NAFTA members were to adopt a system of common external tariffs to replace their existing differentiated external tariffs, a system based on trade weights would have less distortive effects on trade and welfare than a system based on simple averages or production-weighted tariffs.