Danielle - First ASCE does not develop building codes, it develops industry consensus standards, as do many other organizations including AISC, ACI, TMS, etc. Many of these standards, e.g. ASCE 7, ASCE 41, ACI 318, AISC 360 are adopted by reference into the building codes, and once this occurs, to the extent adopted, become part of the codes.
ASCE develops its industry consensus standards, as do most other Standards Development Organizations, following procedures promulgated by the American National Standards Institute (ANSI). ASCE's Codes and Standards Activities Division (CSAD) maintains a set of procedures that comply with the ANSI requirements. CSAD also appoints a number of standards committees, each of which is responsible for development of a particular standard or standards. Each of these committees develop their own rules and procedures, so the process can vary quite a bit for each standard. There are some general things that apply however:
1- Each Standards committee has to be "balanced." That is, it must have members who are representative of various stakeholders including designers, producers (e.g. manufacturers, contractors, suppliers), regulators, researchers, etc., and no one stakeholder group can dominate the vote in sufficient numbers to result in unbalanced requirements.
2- Membership in ASCE standards committees are open to anyone. Generally, ANSI standards must be updated and reissued once each 5 years (in some cases this extends to 6). Therefore, ASCE appoints its standards committees on a cycle that matches this calendar. Most committees have two types of members - voting members and associate members. Any interested ASCE member is guaranteed a slot as an associate member on any committee they volunteer for. However, once appointed, to maintain membership, committee members must be active participants, meaning attend meetings and vote on ballots.
3- Anyone can propose the development of a new standard by petitioning CSAD with a request to form a committee to develop the standard. The petition must include a discussion of the topics the standard will cover and why it is important to the profession that such a standard be developed. If CSAD agrees a committee will be appointed.
4- Once a committee is appointed and working, anyone may propose a change to the standard, although it is easiest for committee members to do so. The ASCE 7 Committee actually posts a "Proposal Change Form" online on the ASCE 7 web page, that can be submitted electronically. Each proposal must include the specific language proposed to be added, deleted, or modified (in track edit format), together with an explanation for why this change is needed, and what the likely cost impacts of the change will be if adopted. The committee will then go through a formal consensus voting process to determine whether the proposal will be adopted, adopted in modified form, or rejected. In this voting process, each voting member must vote to "approve", "approve with comment" or "oppose." Opposing votes must be accompanied by a statement as to why the voter believes the proposal is not appropriate, and what changes to the proposal, if any, could change this. If a majority of the voters approve the proposal, then the negative comments must be resolved. Resolution can be obtained by revising the proposal as suggested in the comment, or by finding the negative comment nonpersuasive. A majority vote of the committee is required to confirm this resolution.
5- Once the standards committee has completed its process, and is ready to publish the new (or revised) standard, the new standard is posted for public comment. During this period, anyone can comment on the validity or desirability of anything in the standard, whether it is new or not. The committee must then resolve the public comments the same as it does negative ballots during committee votes.
6- Once public comment and comment resolution is complete, CSAD reviews the processes and approves the standard, and it is published. Sometimes, ANSI will also conduct an eternal audit of the processes, to make sure that the standard was developed in a balanced manner subject to their requirements.
The International Code Council (ICC) develops a series of model building codes including the International Building Code, International Existing Buildings Code, International Residential Code, etc. that are adopted by most US communities as the basis for their local building codes. Standards organizations, like ASCE try to time the publication of their standards so that ICC can adopt the updated standards into an upcoming edition of their model codes. The next major editions of the I-codes will be published in 2024 and to be included in those codes, standards had to be completed and submitted for adoption in 2021/early 2022. Thus many industry standards have been updated in the last year including the ASCE 7 standard as well as the various standards published by AISC, TMS and others. ASCE 41, which is an important standard governing seismic evaluation and retrofit of existing buildings will be published in 2023.